pathology spot exams

Question 1

Epithelial neoplasms

Answer 1

Epithelial tumors are cohesive and form clusters or sheets. They can show trabecular, circular to papilliform arrangements. Acini may be seen in cells that produce secretory product. Examples of epithelial tumors include perianal gland adenoma, transitional cell carcinoma, biliary carcinoma, squamous cell carcinoma. Epithelial cells generally have the following features:

Large, round to polygonal cells
Distinct cell borders
Tightly adherent to each other
Round to oval nuclei that can be basilar in columnar cells or eccentric in other cell shapes

Epithelial tumors can be benign (adenoma) or malignant (carcinoma). Benign versions consist of well-differentiated cells that can be difficult to distinguish from normal tissue (unless in excess for the aspirated site) or hyperplastic lesions (which may require evaluation of tissue architecture, e.g. normal architecture and arrangement around ducts would indicate hyperplasia versus neoplasia for skin adnexal tumors). Malignant epithelial cells usually demonstrate cytologic criteria of malignancy particularly as they become more aggressive or advanced. However, some carcinomas (e.g. the rare perianal carcinomas) do not always show features of malignancy but behave in a malignant fashion.

Question 2

Mesenchymal neoplasms

Answer 2

Mesenchymal neoplasms carry features of their embryonic tissue of origin, the mesenchyme. The cells are generally individualized and spindled in shape. They can be seen in aggregates (not clusters), often held together by extracellular matrix. They do not typically demonstrate cell-to-cell adhesion. Due to increased matrix production, there are some mesenchymal tumors (e.g. fibroma) that do not exfoliate well and aspirates may be of low cellularity making a definitive cytologic diagnosis difficult. Examples include myxoma, fibrosarcoma, osteosarcoma, melanoma and hemangiosarcoma. Mesenchymal tumors generally have the following features:

Spindle, oval or stellate-shaped cells
Indistinct cell borders, that taper into the background
Round to oval to elongate nuclei that are usually centrally located
Cells are scattered individually or in aggregates, usually within matrix.
Less cellular than the other tumors due to matrix
Matrix can be present in the background as well as within aggregates

As for epithelial tumors, mesenchymal tumors can be benign (“..oma”) or malignant (“sarcoma”). Some types of mesenchymal tumors, e.g. soft tissue sarcomas, are called sarcomas, even though they do not metastasize quickly. They are, however, locally invasive. There are also certain types of mesenchymal tumors that mimic epithelial tumors

Question 3

Discrete (round) cell neoplasms

Answer 3

Discrete or round cell tumors often are of hematopoietic origin (lymphoma, histiocytic, mast cell tumor) and as the term suggests, consists of individualized round cells. Cells tend to exfoliate readily and aspirates are often of high cellularity. We can use morphologic features of the cells, including the presence or absence of granules and cytoplasmic and nuclear features, to determine the type of round cell tumor.

Mast cell tumor
Histiocytoma
Plasmacytoma
Lymphoma
Transmissible venereal tumor

Question 4

Mast cell tumor

Answer 4

These are readily recognized by the presence of purple cytoplasmic granules.
They also have round eccentric nuclei with smooth chromatin. The nuclei can be hard to see as the granules soak up the stain
The degree of granularity varies between tumors. Granules may be harder to discern with water-based stains, such as Rapid stains, particularly in the less well-granulated tumors.
Low grade tumors are typically well-granulated. Higher grade tumors can be poorly or well-granulated and nuclear criteria of malignancy (nuclear atypia, binucleation, large nuclei, mitotic figures) are more reliable than granularity for determining the grade of mast cell tumors on cytology. Tumor grading for dermal (not subcutaneous) mast cell tumors in dogs is best done by histopathology.

Question 5

Histiocytoma

Answer 5

Round to oval with variably distinct cytoplasmic borders.
Moderate to abundant amounts of clear to light blue cytoplasm
Nuclei are eccentric and round to oval to indented
Nuclei have finely stippled chromatin and nucleoli are not apparent
Cells are often found dispersed within a moderately blue background
Minimal cellular atypia, uniform cell size and morphology – they have a bland appearance
Regressing tumors are associated with increased numbers of small lymphocytes (tumor infiltrating cytotoxic T-cells)
Note: Histiocytomas generally consist of very bland, minimally atypical cells. If a high degree of cellular atypia (numerous criteria of malignancy) are found and a histiocytic lineage is still suspected, histiocytic sarcoma should be considered a differential diagnosis.
The main differential diagnosis is an extramedullary plasmacytoma. Lightly stippled chromatin, abundant light blue cytoplasm, indented nuclei and the blue background are used to distinguish between these lesions (not all features may be present in every tumor).

Question 6

Plasmacytoma:

Answer 6

These arise from plasma cells, which form tumors (usually solitary) in extramedullary sites, such as the skin (digit, ears, mouth) in dogs.

Round to slightly oval cells
Distinct cell borders
Variable amounts of blue cytoplasm (often deep blue), some have perinuclear clear zones
Nuclei are round, occasionally oval, and eccentric
Nuclei have clumped chromatin and nucleoli are not apparent
More atypia (anisocytosis and anisokaryosis) than histiocytic tumors
Binucleation and, occasional, multinucleation is common. Multinucleated cells may show marked intracellular anisokaryosis
Amyloid may be present in skin tumors.
The main differential diagnoses are a histiocytoma or plasmacytoid variants of lymphoma. Compared to a histiocytoma, the cells have more distinct boundaries, darker cytoplasm, rounder nuclei (even in multinucleated cells) and clumpier chromatin. They may have perinuclear clear zones. With plasmacytoid variants of lymphoma, cells with higher nuclear to cytoplasmic ratios resembling lymphocytes are expected to be present.

Question 7

Endocrine/neuroendocrine tumors

Answer 7

These tumors have a characteristic appearance, forming packets of cells. Cells often exfoliate in large numbers but are fragile and aspirates contain many bare nuclei from ruptured cells, hence some people call them “naked nuclei” neoplasms. They are of secretory epithelial (producing hormones, e.g. thyroid tumors) or neuroectodermal origin, with the latter secreting neurotransmitters, such as epinephrine in phaechromocytomas. Many of these tumors have quite uniform or bland cytologic features, but show aggressive malignant behavior (e.g. thyroid carcinomas in dogs), therefore cytologic criteria of malignancy are unreliable and we go by the known biologic behavior of the tumors. The type of endocrine or neuroendocrine tumor is generally determined by site, e.g. a cervical neck mass could be thyroid or parathyroid in origin, with the former being more common. In some types of tumors, we can be more definitive, for example thyroid follicular tumors can contain tyrosine granules (blue green pigment) in the cytoplasm.

Round to polygonal cells found in cohesive packets or small sheets
Nuclei are round to oval and central to eccentric
Nuclear chromatin is fine to smooth
Indistinct cell borders

Question 8

mitotic figures

Answer 8

A mitotic figure is a cell that is in the process of dividing to create two new cells.
Mitotic figures are easy to see because the genetic material inside the nucleus changes colour and shape before the cell divides.

Counting mitotic figures (MF) in tumors is one of the most widely used methods
of predicting tumor behavior. The mitotic count (MC)* is a rapid, inexpensive test that can be
performed by any pathologist, is part of many grading schemes, and aids in clinical prognostic
decisions.

Prometaphase
Central dark aggregate
Spikes/projections

Metaphase-
Linear or ring shaped
Spikes/projections

Anaphase -
2 separated aggregates
Distances variable

Telophase (1 MF)-
Separated aggregates
Cleavage furrow

atypical mf:
Multipolar-
More than 2 spindle
poles in any phase

Asymmetrical bipolar-
Unequal size of
chromosome clusters

Chromosome Bridging-
Chromosomes
stretching from one
cluster to opposite pole

Chromosome Lagging-
Fragments not in
contact with cluster

Question 9

haematoxylin and eosin stain

Answer 9

Hematoxylin shows the ribosomes, chromatin (genetic material) within the nucleus, and other structures as a deep blue-purple color. Eosin shows the cytoplasm, collagen, connective tissue, and other structures that surround and support the cell as an orange-pink-red color.

Question 10

Livor mortis

Answer 10

Livor mortis, also known as hypostatic congestion, is a post mortem change that occurs when blood pools on the dependent side of a dead animal due to gravity.

Question 11

Psuedomelanosis

Answer 11

is a post mortem change
Green-blue staining by FeS.
FeS formed by H2S from putrefactive bacteria and iron from Hb from lysed RBC’s.
Will progress to appear back under the right circumstances

Colour is due to the development of blackish particles of ferrous sulphide in the tissues.

The sulphide part is due to the development of hydrogen sulphide in the putrefying tissues.
The iron part comes from the haemoglobin of the blood.
    Haemoglobin is acted on in putrefaction by bacteria, which split off the iron at the same time as they produce hydrogen sulphide.
        Components combine to form ferrous sulphide.

Discolouration therefore depends on the presence of both blood and bacteria.

Question 12

Putrefaction

Answer 12

Putrefaction is the action of bacteria on tissues after death.
bacteria can produced gas bubbles. The tissue will likely feel soft and smell.

Question 13

post mortem evidence of
Barbiturate euthanasia

Answer 13

enlarged spleen-
Congestion is due to passive engorgement of a vascular bed.
Occurs by decreased outflow or increased inflow of blood.
Can be acute or chronic.
Acute occurs with barbiturate euthanasia due to smooth muscle relaxation, resulting in blood pooling in the vessels or typically the spleen, liver and lungs.

Question 14

Chilling artefact

Answer 14

Chilling a carcass will often result in opacity of the cornea and/or lens. Warming the carcass back to room temperature will return this to normal

Question 15

Diffuse red discolouration of the intima of the base of the thoracic aorta is evidence of which post mortem change?

Answer 15

Haemoglobin imbibition

Haemoglobin imbibition is due to the red discolouration of tissue due to the release of haem from lysed erythrocytes.
Whilst this is most commonly seen as a freeze-thaw artefact as freezing expands erythrocytes and bursts them en masse, this can also happen if a carcass is left long enough post mortem for the ertyrhocytes to lyse “naturally” in organs that contain a lot of blood, such as the right side of the heart and large vessels.

Question 16

The post mortem change negatively affected by cachexia is

Answer 16

Rigor mortis

cachexia-weakness and wasting of the body due to severe chronic illness.

Question 17

Rigor mortis

Answer 17

a post mortem change
Appearance is that of hyperextended limbs and neck
Onset is 1-6 hours after death, lasts 1-2 days.
It is due to depletion of ATP and glycogen which are required to RELAX muscles and is reversed by autolysis
Rigor mortis also occurs in the heart, so will typically see the left ventricle devoid of blood as it contracts
May not see rigor mortis at all if an animal is cachexic

Question 18

Post mortem cooling of the carcass is known as

Answer 18

Algor mortis

Question 19

Melanosis in the pig is …

Answer 19

incidental
Known as congenital macular melanosis

Question 20

agonal changes

Answer 20

take place immediately before death and are due to circulatory failure.

Question 21

Desiccation

Answer 21

The postmortem drying of mucous membranes and delicate skin surfaces may result in artifactual changes in color or texture. This desiccation process begins immediately upon death and may progress quite rapidly in normally moist mucous membranes. This effect is often most prominent in the eye in humans, resulting in a horizontal band of red to brown-black discoloration of the sclera where the eyelids fail to close; this is commonly referred to as tache noire

Skin surfaces most commonly affected are thin, delicate areas such as the lips and genitalia. The gross appearance is dark red to black with a variably irregular surface.

Question 22

Decomposition- autolysis

Answer 22

The most definitive and distinctive postmortem change is the decomposition of the soft tissues. Immediately upon death, decomposition begins on a molecular level because of the failure to maintain ion gradients and cell membrane integrity. As cell membranes begin to degrade and eventually rupture, they spill their contents into the interstitium, exposing the cell membranes of surrounding cells and connective tissue fibers to cytosolic proteolytic enzymes that further degrade exposed cell surfaces. This chain reaction of decomposition that results from the digestion of tissues by intrinsic enzymes is autolysis

Macroscopically
early autolysis may not be obvious
with time tissue becomes paler, soft, friable and may exude fluid
mucosal linings may slough off easily e.g. intestine
Microscopically
early autolysis cells will swell
cytoplasmic and nuclear detail are lost
cells lose their cohesion to each other
no inflammatory response

Question 23

Decomposition- autolysis

Answer 23

The most definitive and distinctive postmortem change is the decomposition of the soft tissues. Immediately upon death, decomposition begins on a molecular level because of the failure to maintain ion gradients and cell membrane integrity. As cell membranes begin to degrade and eventually rupture, they spill their contents into the interstitium, exposing the cell membranes of surrounding cells and connective tissue fibers to cytosolic proteolytic enzymes that further degrade exposed cell surfaces. This chain reaction of decomposition that results from the digestion of tissues by intrinsic enzymes is autolysis

Question 24

decomposition-putrefaction

Answer 24

Bacterial putrefaction typically begins slightly after autolysis, which creates ideal conditions for bacterial growth.

Macroscopically -
Carcass blown up
Gas bubbling
Psuedomelanosis
A blue-green to block post mortem discoloration due to bacterial breakdown of haemoglobin produces hydrogen sulphide.

Microscopically-
Bacteria
typically rods in farm animals (Clostridia)
No inflammation

Question 25

what are the two types of decomposition

Answer 25

autolysis putrefaction

Question 26

phases of decomposition

Answer 26

Fresh stage: death until bloating begins (4–36 days) * Bloated stage: onset of bloating until resolution of bloating (3–19 additional days) * Decay stage: resolution of bloating until drying of carcass (6–183 additional days) * Dry stage: drying of carcass until no evidence of carrion insects (13–27 additional days)

Question 27

Mummification

Answer 27

Under dry environmental conditions, either cool or warm, with low humidity and sufficient ventilation, the body may become desiccated rather than undergoing the more typical process of decomposition.48 The skin becomes tight and yellow-brown to black and takes on a leathery or parchment paper consistency.61 As a result of exposure to such dry conditions, the processes of autolysis and putrefaction are retarded or completely inhibited, and the tissues become dehydrated. The resulting desiccation produces changes in the body such as contraction or wrinkling of skin, retraction of the nailbeds and finger tips, and contraction of the erector pili muscles

Question 28

inhibition of bile pigment after death

Answer 28

One of the earliest local colour changes. Bile salts diffuse out of the gall bladder. Stain nearby tissue like the liver, gut, stomach and omentum. NOT the same thing as jaundice- more generalised Generalised discoloration of tissues due to bile pigments seen in the living animal.

Question 29

external exam of a post mortem

Answer 29

Overview and BCS Crown rump length Pelage and skin Eyes Feet Faecal or urine staining Blood Mucous membranes Dentition

Question 30

The pluck comprises....

Answer 30

Tongue Thyroid glands Trachea Oesophagus Lungs Heart Thymus

Question 31

summerise the steps of a post mortem

Answer 31

External exam Stabilize carcass Skin the ventral aspect of the carcass Open the abdomen Check for negative pressure Open the thoracic cavity Remove the pluck Check for gall bladder patency Remove the adrenal glands Remove the spleen and liver Remove GIT Remove the urogenital tract Open and examine at least seven limb joints Remove and bisect a femur for assessment of bone marrow If indicated in the history, for example in cases of trauma or neglect, skin entirely A technician will remove the brain and eyes Arrange all removed organs neatly on a chopping board GIT should be placed on a separate board Examine organs and take samples

Question 32

what bosy systems may be involved in sudden death

Answer 32

nervous cardiovascular respiritory

Question 33

How can the autonomic system be damaged?

Answer 33

Trauma Hypoxia/anoxia Oedema Toxins Seizures neurogenic shock results in widespread and massive vasodilation

Question 34

Explain the pathophysiology of death due to cardiovascular failure

Answer 34

Pathophysiology of death due to cardiac failure: Structural Electrical Ischaemic Pathophysiology of death due to vascular failure: Ischaemic Shock Pathology of the vessels Evidence of haemorrhage? Evidence of disease of organs involved in fluid and electrolyte haemostasis?- GI Urinary Endocrine Open pulmonary arteries and aortic bifurcation Take sections of kidney - End arteries therefore good place to look for small thromboemboli Examining the heart- Pericardial effusion? Weight Measurements Gross lesions Sections for histopathology

Question 35

Explain the pathophysiology of death due to respiratory failure

Answer 35

"Respiratory failure occurs when there is inadequate exchange of O2 and CO2 to meet the needs of metabolism, which leads to hypoxaemia, with or without hypercarbia" Respiratory failure can be divided into: Type I respiratory failure, in which processes that impair oxygen transfer in the lung cause hypoxaemia (acute or hypoxaemic respiratory failure) Type II respiratory failure, in which inadequate ventilation leads to retention of CO2 , with hypercarbia and hypoxaemia ‘Mixed’ respiratory failure, in which there is a combination of type I and type II respiratory failure (acute-on-chronic respiratory failure).  The most common cause of death due to respiratory failure in dogs is reported to be accidental asphyxiation due to choking on food material Acute respiratory distress syndrome Secondary to inflammation/infections elsewhere in the body Often pancreatitis Sudden but likely expected and/or dog already hospitalised BOAS Heat stroke Peri-anaesthetic

Question 36

Sudden death – respiratory – pulmonary haemorrhage in horses

Answer 36

Exercise-associated fatal pulmonary haemorrhage (EAFPH) A term first reported in 2015, used to describe fatal pulmonary haemorrhages in racehorses Fatal pulmonary haemorrhage is one of the most frequent causes of sudden death in racehorses, and such lethal pulmonary bleeding has been reported long before the acronym EAFPH was coined The occurrence of acute cardiac failure or spastic contraction of pulmonary postcapillary sphincters have been listed as possible pathogenetic mechanisms for the occurrence of EAFPH, but this has not been proven Exercise-induced pulmonary haemorrhage (EIPH) The term was first used in1981 to describe epistaxis of pulmonary origin, especially after exercise.  EIPH is believed to be an important cause of reduced athletic performance, especially in cases with severe bleeding, however its role in sudden death is complicated

Question 37

blood cyst

Answer 37

Focally raising the contour of the atrial surface of the mitral valve is a single, smooth red, round focus, measuring approximately 3mm in diameter Seen frequently in young ruminants Incidental

Question 38

endocardiosis

Answer 38

the development and accumulation of fibrous tissue within the heart valves which in turn alters the physical structure of the valves Multifocally at the line of closure of the mitral valve the valve is thickened and pale cream with raised coalescent nodules. Age-related change commonly seen in dogs incidental

Question 39

Ascarid migration

Answer 39

incidental Multifocally affecting all lobes of the liver are poorly-demarcated, flat, vaguely round, white to pale tan foci Various species

Question 40

Hepatocellular adenoma/carcinoma

Answer 40

incidental Description: Entirely obliterating the left lateral lobe of the lever is a large nodular vaguely round pink to red firm mass Only an issue if they rupture, can grow quite large in old dogs completely un-noticed However, a small proportion will produce insulin-like peptides or IGF-2 -> hypoglycaemia

Question 41

Nodular hyperplasia

Answer 41

incidental a benign liver lesion that is composed of a proliferation of hyperplastic hepatocytes surrounding a central stellate scar. There are however lots of malignant neoplasms that can form masses in the spleen: Haemangiosarcoma Lymphoma Histiocytic sarcoma Focally expanding the parenchyma and raising the contour of the spleen is a focal, well-demarcated, black to red to pink mass

Question 42

siderotic plaques

Answer 42

benign golden brown or black patches that are frequently seen on the surface of the spleen. They result from focal accumulations of stored iron (hemosiderosis) derived from erythrophagocytosis and subsequent hemoglobin breakdown Focally extensively raising the capsule of the lateral aspect of the body of the spleen are raised cream to white to grey gritty multifocal to coalescing plaques Accumulations of debris associated with erythrocyte turnover. Histopathologically are quite pretty with multiple variations of metabolised haem Haemosiderin Hemotoidin Gamna-Gandy bodies

Question 43

Renal cysts

Answer 43

Can be incidental Can also be pathological Quantifying and contextualising is important

Question 44

Describe and explain the process of PCR

Answer 44

Veterinary molecular diagnostics Uses oligonucleotide (hort single strands of synthetic DNA or RNA that serve as the starting point) primers to amplify region of interest (gene) Cycles of heating and cooling drives each step Millions of copies can be produced in minutes Number of copies provides information on presence and/or amount of starting material occurs in steps- denaturation-High temperature breaks hydrogen bonds holding base pairs together ‘Melts’ double-stranded DNA revealing bases in specific order annelaing- At cooler temperatures, complementary bases can bind Oligonucleotide primers ‘match’ small regions of the target area (gene of interest) They bind to the matching areas (anneal) Primers must be designed so that one matches the sense strand and the other matches the antisense strand extension/elongation- Temperature raised to approximately 74°C Synthesis of new complementary DNA strand from 3’ end of primer Only regions where primers bound will be amplified/copied. So it’s really important that they only match the region we’re interested in Specificity is very high Sensitivity is very high Rapid turnaround time Overcomes culturing restrictions PPV can be low Not for all assays/samples Requires specialist equipment

Question 45

semi-quantitative PCR

Answer 45

The amount and size of the PCR product can be visualised using staining and gel electrophoresis This visually confirms if our pathogen / gene of interest / strain is present Known as semi-quantitative PCR

Question 46

qPCR – SYBR assays

Answer 46

SYBR Green is one of the most commonly used fluorescent dyes in qPCR. It binds to double-stranded DNA molecules by intercalating between the DNA bases. Once intercalated to DNA, SYBR Green becomes less mobile, causing its energy to be released as fluorescence. Therefore, the fluorescence intensity is directly associated with the concentration of double-stranded DNA, which can be measured at the end of each amplification cycle to determine the PCR progress.

Question 47

qPCR – TaqMan assays

Answer 47

Each TaqMan Assay employs a TaqMan probe that specifically anneals to a complementary sequence between the forward and reverse primer sites. When the probe is intact, the proximity of the reporter dye to the nonfluorescent quencher (NFQ) results in suppression of reporter fluorescence. Probe cleavage by DNA polymerase during primer extension separates the reporter dye from the NFQ, resulting in increased fluorescence of the reporter. enable the detection of a specific PCR product as it accumulates during PCR cycles.

Question 48

qPCR

Answer 48

stands for quantitative polymerase chain reaction and is a technology used for measuring DNA using PCR The main difference between the two is that qPCR is a real-time method, while PCR is not. This means that with qPCR, you can monitor the amplification of your target DNA in real-time as it is happening

Question 49

RT-PCR

Answer 49

Reverse transcriptase PCR (RT-PCR) Uses reverse-transcriptase enzyme to produce double stranded DNA from RNA This provides template for normal PCR Can also be incorporated into qPCR = RT-qPCR commonly used in the diagnosis and quantification of RNA virus infections (e.g., human immunodeficiency virus and hepatitis C virus) and the analysis of mRNA transcripts such as those produced by translocations commonly associated with non-Hodgkin's lymphomas, leukemias, and sarcomas.

Question 50

PCR for viral infections

Answer 50

Serological assays are not always feasible when detecting viral infections Lack of species-specific secondary antibodies Suitable cells for growth and titration are not available

Question 51

daignostics for bacterial infections

Answer 51

Culture Stain Test

Question 52

Helicobacter diagnostics

Answer 52

Many different species that can infect veterinary species Individuals can be infected with more than one species at the same time Fastidious bacteria (difficult to culture) PCR primers designed to detect a single species Rapid test

Question 53

diagnostics for fungal infections

Answer 53

Slow growth in culture Diagnosed histologically Can be diagnosed with PCR- PCR can be used if no identifiable fungal species cultured or morphologically identifiable Pathogen-specific primers Generic fungal primers (e.g. rRNA) Genus-specific primers

Question 54

non invasive molecular tests

Answer 54

Better animal welfare Can be performed more frequently Multiple samples over short period (sequential samples) Detect agents shed for short periods or intermittently faeces Skin swabs Fur swabs Environmental tests- Soiled bedding Environmental swabs Air filters Cage tops Does not require handling Culturing not always possible PCR can detect presence of infectious agents

Question 55

Positive predictive value (PPV)

Answer 55

The probability that a test positive animal is diseased Disease agents may colonise healthy animals as well PCR detects DNA/RNA in live and dead organisms May be positive even if infection is controlled or cleared Interpretation of results for a single animal can be difficult

Question 56

PCR inhibitors

Answer 56

can result in false negatives Natural inhibitors include: Bile salts Polysaccharides in faeces Haem from blood Glycogen and fats in tissues Proteinases in milk Urea in urine Co-purified with DNA/RNA Extraction kits designed to remove them

Question 57

summerie the use of Organism vs antibody detection

Answer 57

Detection of organisms gives most information Assays not always available or optimal Antibody detection still commonly used Combinatory approach can be used PCR positive result can occur prior to seroconversion – prove infection in acute cases PCR can be negative later in course of disease Serum antibodies are detectable

Question 58

Serology

Answer 58

Detect antibodies or antigen in blood sample Indirect method Limitations due to lack of species-specific secondary antibodies Seropositivity may not indicate acute infection ELISA

Question 59

ELISA

Answer 59

Enzyme Linked Immunosorbent Assays 2 types of ELISA: Direct test - Antibodies used to test for antigen Indirect test – Antigens used to test for antibody Can test for: Bacteria or bacterial toxins Viruses Protozoa Ab to any of these or Ab to parasites, yeasts, Plate coating: Samples are diluted in buffer, then pipetted into a microwell plate. After incubation, the solution is discarded and plate is washed with a wash buffer. ONLY immobilised antigen/antibody remains Plate blocking: Blocking buffer is added to the plate. This binds to any remaining protein-binding sites in the coated wells, reducing non-specific binding of antibodies to the plate. Plate then washed again Antibody incubation: Following incubation, wash away unbound antibodies with a wash buffer. Detection: The enzymes covalently attached to the antibodies will start producing a coloured reaction product. Stop solution is added to terminate the colour development and the absorbance of each well is read. The signal intensity allows you to determine whether a sample contains the antigen/antibody of interest, and at what concentration. By stopping all wells at the same time (with stop solution) the signal intensity if indicative of the antigen (or antibody) concentration.

Question 60

Direct ELISA

Answer 60

Detection of antigen: Sample proteins immobilised on plate/well Enzyme labelled antibodies added Antibodies bind to antigen Enzyme-specific substrate added Reaction takes place and produces colour Colour change (signal intensity) detected

Question 61

Indirect ELISA

Answer 61

Detection of antibody: Antigen immobilised on plate/well Sample is added Any antibodies present will bind to antigen Enzyme-labelled secondary antibody added Substrate added Reaction takes place and produces colour Colour change (signal intensity) detected

Question 62

Sandwich ELISA

Answer 62

Detection of antigen: Plate/well coated with capture antibodies Sample is added Any antigen present will bind to antibody Direct: enzyme-labelled antibody used Indirect: Enzyme-labelled secondary antibody added Substrate added Reaction takes place and produces colour Colour change (signal intensity) detected

Question 63

Competitive ELISA

Answer 63

Sample antigen/antibody competes with reference antigen/antibody Analyte concentration is indicated by signal interference Coat plate with reference antigen Incubate sample (unknown antigen concentration) with limited amount of labelled antibodies Low antigen conc. in sample = large portion of labelled antibodies have nothing to bind to Add this mixture to the antigen coated plate Any free labelled antibodies will bind to reference antigen Wash plate to remove antibodies bound to sample antigen Add substrate Stronger colour = less antigen present in sample

Question 64

Epithelial tissue

Answer 64

All endoderm and some ectoderm origin Cells form bulk of parenchyma of organ, glands or line organs- Hepatocytes Skin GIT Bladder Cell-to-cell and cell-to-basement membrane adherence

Question 65

Mesenchymal tissue

Answer 65

Mesoderm origin Supporting cells Fibroblasts -> collagen Endothelia Bone

Question 66

Round cell tissue

Answer 66

Mesoderm origin Cells of the haemo-lympho system- Erythrocytes Leukocytes

Question 67

histological appearence of epithelial tissue types

Answer 67

Polygonal Poorly-defined cell borders Abundant cytoplasm Polar to central round nuclei Basement membrane

Question 68

histological appearence of mesenchymal tissue types

Answer 68

Histological appearance Fusiform/spindloid Poorly-defined cell borders Variable cytoplasm Fusiform/spindloid nuclei Extra cellular matrix

Question 69

histological appearence of round cell tissue types

Answer 69

Round Well-defined cell borders Individualised Variable cytoplasm Round to variable nuclei

Question 70

Two types of antibodies for immunohistochemistry

Answer 70

Monoclonal- Antibodies produced by the same clone of plasma B cells Hybridisation with tumour cells Higher specificity, lower sensitivity Polyclonal Heterogeneous mix of antibodies Derived from the immune response of multiple B-cells Each one recognizes a different epitope on the same antigen Higher sensitivity, lower specificity

Question 71

in immunohistochemistry, IHC can be used to differentiate between

Answer 71

inflammation and neoplasia A classic example is inflammatory bowel disease versus lymphoma In both diseases lymphocytes accumulate in the intestine If inflammatory this is polyclonal Multiple lymphocytes replicating If neoplastic this is monoclonal One cell becomes neoplastic and replicates

Question 72

what can cytokeratin and vientin be used to differentaite betweeen in immunohystochemistry

Answer 72

Cytokeratin- proteins found in the intracytoplasmic cytoskeleton of epithelial tissue. Vimentin- a type III intermediate filament (IF) protein that is expressed in mesenchymal cells. therefore the presence of eeach can differantaite between epithelial and mesenchymal cell

Question 73

Immunohistochemistry

Answer 73

A laboratory method that uses antibodies to check for certain antigens (markers) in a sample of tissue. The antibodies are usually linked to an enzyme or a fluorescent dye.

Question 74

Indications for a kidney biopsy:

Answer 74

Proteinuria Acute renal failure Chronic renal failure Renal azotaemia that cannot be categorized as acute or chronic renal failure

Question 75

Proteinuria is, once a urinary tract infection is ruled out,  almost always due to

Answer 75

disease of the glomerulus

Question 76

low urine specific gravity, which would indicate reduced ability to concentrate urine, is typically due to

Answer 76

disorder of the tubule. 

Question 77

Podocytes

Answer 77

highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman's capsule. The structure of the glomerular capillaries is important in determining the rate and selectivity of glomerular filtration. The glomerular capillary wall consists of three layers: the capillary endothelium the basement membrane the visceral epithelium = podocyte

Question 78

PAS and Trichrome are ....

Answer 78

special histochemical stains that can be used to highlight immune complex deposition in glomeruli

Question 79

IM-glomerulonephritis

Answer 79

due to immune complex deposition within the glomerular tuft Results from the deposition of immune complexes in glomeruli formation of antibodies against the glomerular basement membrane activation of inflammatory cascade PAS and Trichrome are special histochemical stains that can be used to highlight immune complex deposition in glomeruli Immunofluorescence and transmission electron microscopy can be used to confirm immune complex deposition in glomeruli Any condition that stimulates the immune system for long periods of time can cause IM-glomerulonephritis

Question 80

what are the three types of error

Answer 80

Pre-analytical Specimen collection Analytical The test Post analytical Interpreting

Question 81

Pre-analytical error

Answer 81

Checklist: Is the sample haemolysed/lipaemic/icteric? Has my sample been taken/handled properly? Clotted? Artefacts can occur if not stored properly Serum should be separated/spun soon after collection Too much or too little sample? Contamination by anti-coagulant Delay the right test?- Antigen versus antibody Most useful test? FNA in canine mammary tumours vs FNA in canine diffuse large B-cell lymphoma in a lymph node More than one test Cushing’s CBC and biochem Urine cortisol:creatinine ratio Basal cortisol ACTH-stim test Low-dose dex suppression test High-dose dex suppression tes Imaging

Question 82

Analytical error

Answer 82

Sensitivity- ability of a test to detect diseased animals correctly the proportion of diseased animals testing positive SnOUT Specificity- ability of a test to give the correct answer if not diseased  i.e. proportion of non-diseased animals testing negative.​ SpIN i.e. a highly specific test will have few false positive Eg: bTB skin test Sensitivity = 57% If 100 infected cattle are tested, it will potentially fail to detect 43 infected animals = Lots of false negatives Specificity = 99.5% If 100 uninfected cattle are tested, it wrongly diagnose <1% as positive = Few false positives This is important as it is a screening test

Question 83

post-analytical error

Answer 83

dependent on history and location

Question 84

karyolysis

Answer 84

he complete dissolution of nuclear components of a dying cell.

Question 85

karyorrhexis

Answer 85

the destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm.

Question 86

combination of increased AST and TBil, alongside the low haematocrit indicates what process?

Answer 86

haemolysis

Question 87

poikilocytosi

Answer 87

an increase in abnormal red blood cells of any shape that makes up 10% or more of the total population. Poikilocytes can be flat, elongated, teardrop-shaped, crescent-shaped, sickle-shaped, or can have pointy or thorn-like projections, or may have other abnormal features. e.g heinz bodies oxidative damage

Question 88

Increased creatinine with low urine specific gravity indicates what type of azotaemia?

Answer 88

Renal – free haemoglobin at high enough levels is toxic to the kidney, also this animal is anemic so has reduced O2 carrying capacity which will further damage the kidney

Question 89

azotaemia

Answer 89

elevation, or buildup of, nitrogenous products (BUN-usually ranging 7 to 21 mg/dL), creatinine in the blood, and other secondary waste products within the body

Question 90

Brown mucous membrane is also called what?

Answer 90

Methaemaglobinaemia

Question 91

Define haemostasis and platelet role in haemostasis

Answer 91

Haemostasis Complex physiological process activated vascular injury. Imbalance in the haemostasis pendulum results in haemostatic disorder characterised by either thrombosis or haemorrhage  Cellular component: platelets, especially but also fibroblasts Soluble proteins (coagulation factors and inhibitors) Insoluble proteins (extracellular matrix proteins). Haemostatic component interplay Primary haemostasis (platelet plug formation) Secondary haemostasis (fibrin clot crosslinking) Fibrinolysis

Question 92

Platelet count

Answer 92

Usually perform as part of complete blood count and haemostatic disorder screening Rule out/rule in quantitative platelet level disorder thrombocytopenia/thrombocytosis? Methods Platelet count estimation (blood smear) Manual count using haemocytometer Automated counter Diagnostic considerations Appropriate venipuncture to reduce endothelial damage and platelet activation/clumping Use of EDTA tubes prevent platelet clumping and clot formation Proper sample handling and storage  Test sample ASAP!!! Direct blood tube contact with ice-pack could trigger platelet clumping (false-positive thrombocytopenia)

Question 93

protiens that contribute to oncotic pressure

Answer 93

Most abundant molecule: ALBUMIN Main driver of oncotic pressure Lots of larger molecules each present in small numbers: GLOBULINS Subdivided into: Alpha, beta, and gamma globulins Includes: Inflammatory cytokines, immunoglobulins

Question 94

Albumin

Answer 94

Produced in the liver at a constant rate Major contributor to plasma oncotic pressure Carries ion molecules (calcium, magnesium)

Question 95

Globulins

Answer 95

Subdivided into: Alpha, beta, and gamma globulins Includes: Inflammatory cytokines, immunoglobulins Produced by many different cell types. Major contributors: Liver: Acute phase proteins (increased during inflammation), coagulation proteins (clotting factors, anticoagulants) Lymphocytes: Immunoglobulins

Question 96

Hyperproteinaemia

Answer 96

High albumin = dehydration High globulins = dehydration, inflammation, neoplasia Neoplasia refers to lymphoma & myeloma, which produce monoclonal immunoglobulins Detection of monoclonal immunoglobulins can be done via serum protein electrophoresis

Question 97

High albumin =

Answer 97

dehydration

Question 98

High globulins =

Answer 98

dehydration, inflammation, neoplasia Neoplasia refers to lymphoma & myeloma, which produce monoclonal immunoglobulins Detection of monoclonal immunoglobulins can be done via serum protein electrophoresis

Question 99

Hypoproteinaemia

Answer 99

Hypoproteinaemia can be categorised as follows: Selective hypoproteinaemia Hypoalbuminaemia Hypoglobulinaemia Total proteins can be WRI Panhypoproteinaemia Both albumin and globulins are below WRI

Question 100

Hypoglobulinaemia

Answer 100

Rare! Encompasses so many proteins, unusual to lose so much of one that it has a significant impact on total globulins. Check dehydration is not masking concurrent hypoalbuminaemia Consider double checking with a reference laboratory Main differential: Immunodeficiency resulting in severe reductions immunoglobulin production (e.g. Severe combined immunodeficiency)

Question 101

Panhypoproteinaemia

Answer 101

When both albumin and globulin are lost together. Two main categories: Protein-losing enteropathy (common)- Differentials: Lymphoma IBD Lymphangiectasia Parasitism Protein-losing dermatopathy (rare → severe burns)

Question 102

enzymes are generally used to check for.....

Answer 102

cellular injury. Commonly measured enzymes can be broadly categorised into those from: Liver Biliary tract Muscle Pancreas Some enzymes are produced by multiple tissues → need to look at panels to work out which tissue is affected. There can be multiple different versions of one enzyme: “isoenzyme”

Question 103

SDH (sorbitol dehydrogenase)

Answer 103

Liver Generally only used in large animals

Question 104

ALT (alanine aminotransferase)

Answer 104

Liver, muscle Much more specific to liver vs muscle. Not useful in large animals. Cat ALT and ALP have much shorter half life compared to dogs → smaller elevations are more clinically significant

Question 105

GLDH (glutamate dehydrogenase)

Answer 105

Liver More stable than SDH Colostrum is high in GGT → increases in calves Can be used to check for passive transfer Also elevated in foals but not due to colostrum

Question 106

AST (aspartate aminotransferase)

Answer 106

Liver, muscle Equally specific to liver vs muscle Long half life longer half life than ck

Question 107

ALP (alkaline phosphatase)

Answer 107

Biliary, bone, intestines, steroid Steroid isoenzyme only in dogs Cat ALT and ALP have much shorter half life compared to dogs → smaller elevations are more clinically significant Canine steroid ALP isoenzyme is elevated with both drugs (corticosteroids, phenobarbital), chronic stress, and hyperadrenocorticism Bone ALP can increase with growth in young animals as well as patients with high osteoblastic activity (e.g. hyperparathyroidism)

Question 108

GGT (gamma glutamyl transferase)

Answer 108

Biliary Small increases significant

Question 109

hepatobiliary markers

Answer 109

Bile acids Bilirubin Cholesterol Albumin Glucose Coagulation factors alt alp sdh gldh ggt ast

Question 110

Bile acid stimulation

Answer 110

Tests the ability of the liver to re-uptake bile acids from the portal vein. Patient is sampled after being starved for 8 hrs, then resampled after being fed. Increases are supportive of either: Reduced hepatocellular function (NB: does not necessarily indicate failure) Portosystemic shunt (blood bypasses liver) Cholestasis (don’t bother running this test if bilirubin is increased!) → bile acids are usually high before and after stimulation testing Bile acid cycle: Produced by hepatocytes and excreted into the bile Degradation occurs in the gut, then the transformed bile acids are reabsorbed Transported to hepatocytes via the hepatic portal vein Hepatocytes uptake the transformed bile acids for reprocessing Bile acid cycle: Produced by hepatocytes and excreted into the bile Degradation occurs in the gut, then the transformed bile acids are reabsorbed Transported to hepatocytes via the hepatic portal vein Hepatocytes uptake the transformed bile acids for reprocessing

Question 111

Bilirubin

Answer 111

Two main types of bilirubin: Unconjugated bilirubin Made during breakdown of heme (from dead RBCs) Insoluble; transported bound to albumin Conjugated bilirubin → negligible levels in health Has been processed by the liver and conjugated with glucuronide Water soluble; majority is transported free Delta bilirubin = conjugated bilirubin that is bound to albumin (tiny amount) Analysers can give three different types of bilirubin measurement: Total bilirubin Total bilirubin = direct bilirubin + indirect bilirubin Direct bilirubin → measured value Total conjugated bilirubin Indirect bilirubin → calculated value (total bilirubin - direct bilirubin) Total unconjugated bilirubin Most analysers give only total bilirubin Causes of bilirubin increases can generally be broken down into: Pre-hepatic = excessive breakdown of heme or inhibition of bilirubin uptake by hepatocytes Haemolysis, fasting (horses, cattle) Unconjugated bilirubin increases, can eventually lead to both being increased Hepatic = reduced ability to conjugate bilirubin Toxic insult, Leptospirosis (dogs, cattle) Both conjugated and unconjugated fractions increased Post-hepatic Gallstones, mucocoele, pancreatitis (cats) Unconjugated bilirubin increases first, then both increase as the system “backs up”

Question 112

Cholesterol

Answer 112

Produced in the liver but other sources include: Uptake from food via lymphatics- Usually triglycerides increase also Release from adipose tissue during negative energy balance- Usually triglycerides increase also Increases can be particularly high if animal is overweight Present within the bile in high concentrations Increases due to: Cholestasis- Look for concurrent increases in bilirubin, GGT, ALP Starvation/anorexia- Usually triglycerides increase also Recent meal Usually triglycerides increase also Nephrotic syndrome- hepatocytes stimulated to make more cholesterol Decreases due to: Reduced intestinal absorption GI disease, hypoadrenocorticism

Question 113

Albumin & Glucose

Answer 113

If the liver is end-stage, then these can drop due to reduced production/storage. Other causes of hypoalbuminaemia already discussed Other causes of hypoglycaemia include: Diabetic ketoacidosis Starvation (puppies, working dogs) Insulinoma → pancreatic neoplasm which produces insulin Artefact → use fluoride oxalate tube

Question 114

link between liver faliur and Coagulation factors

Answer 114

Liver synthesizes coagulation factors Liver failure → prolonged coagulation times

Question 115

Muscular enzymes

Answer 115

ck ast alt

Question 116

CK (creatinine kinase)

Answer 116

Muscle Short half life ast has longer half life

Question 117

Pancreatic lipase

Answer 117

Used to diagnose pancreatitis but can also go up when Glomelular Filtration Rate is reduced. Measured by a multitude of methods: DGGR lipase Not fully sensitive or specific, but good screening test Can increase in dogs with hyperadrenocorticism Drugs can increase DGGR lipase: corticosteroids, herparin Specific pancreatic lipase immunoreactivity (cPLI, fPLI) More specific and sensitive than DGGR lipase SNAP pancreatic lipase immunoreactivity Qualitative test for a quick “yes” or “no” As a general rule, positive = positive, negative = maybe

Question 118

amylase

Answer 118

Used to diagnose pancreatitis but can also go up when Glomelular Filtration Rate is reduced. Poorly sensitive in cats

Question 119

TLI

Answer 119

Usually used to diagnose Exocrine Pancreatic Inefficency (whereby levels are decreased) Can go up with pancreatitis or with incomplete starvation

Question 120

Renal physiology: Proximal tubule

Answer 120

Resorb most electrolytes Activate Vitamin D

Question 121

Renal physiology: Loop of Henlé

Answer 121

Absorption of H2O in the descending limb. Absorption of NaCl in the ascending limb. Creates the medullary concentration gradient required to concentrate urine in the collecting duct.

Question 122

Renal physiology: Distal convoluted tubule & collecting duct

Answer 122

Small amounts of electrolytes resorbed in DCT Collecting duct reabsorbs H2O → concentrated urine

Question 123

Renal physiology: Glomerulus

Answer 123

Electrolytes filtered out. Proteins should remain in blood. Small amount of protein present in canine urine Location of juxtaglomerular apparatus (RAAS)

Question 124

Glomerular filtration rate

Answer 124

Speed at which fluid is filtered out of the blood into the Bowman’s capsule Controlled by: Hydrostatic pressure- The rate at which blood enters the glomerular capillaries The rate at which blood leaves the glomerular capillaries The rate at which filtered fluid moves through the renal tubules Increased in-flow= High cardiac output, High blood pressure → idiopathic, hyperthyroidism Decreased in-flow= Low cardiac output → heart failure, shock, Water loss (decreased hydrostatic pressure) → dehydration Compensation occurs via dilation/constriction of efferent vessel- Compensation limited Reduced flow through tubules Injury to glomerulus Injury to tubules Urinary obstruction → urolithiasis Increased flow through tubules Excretion of osmoactive substances Glucose → diabetes Mannitol → therapy Diuretics Loss of medullary tonicity Psychogenic polydipsia or diabetes insipidus → loss of electrolytes = “medullary washout” Liver failure → loss of urea production Oncotic pressure- Amount of albumin within the peripheral blood Hypoalbuminaemia Loss via: Kidneys → glomerular injury Gut → IBD, lymphoma, lymphangiectasia Skin → burns Decreased production → Liver disease Hyperalbuminaemia Dehydration

Question 125

Renal biomarkers

Answer 125

Urea Creatinine SDMA Others used in literature but not routinely in clinical practice: Clearance of inulin or iohexol Neutrophil gelatinase-associated lipocalin (NGAL) Retinol binding protein

Question 126

Creatinine

Answer 126

Released by muscles at a constant rate Excreted entirely by kidneys - no reuptake Concentration in blood dependent on: Production Higher with heavy muscle mass → greyhounds Lower with muscle wasting → young and elderly patients Rate of excretion (i.e. GFR) Requires damage to 75% of nephrons

Question 127

Urea

Answer 127

Produced by the liver during protein metabolism Excreted by the kidneys - small amount of reuptake Provides the concentration gradient for loop of Henle Concentration dependent on: Production Reduced with liver failure Increased with high protein diet Increased with GI bleeding —> Controversy Rate of excretion (i.e. GFR) Requires damage to 75% of nephrons

Question 128

SDMA

Answer 128

(symmetric dimethylarginine) Released by all nucleated cells at a constant rate Excreted entirely by kidneys - no reuptake Concentration in blood dependent on: Rate of excretion (i.e. GFR) Requires damage to 25% of nephrons NB: Greyhounds have naturally high SDMA

Question 129

Azotaemia

Answer 129

Increase in urea, creatinine, and/or SDMA levation, or buildup of, nitrogenous products Classification: Pre-renal → renal blood supply, increased urea production Renal → problem with the kidney itself Post-renal → obstruction of urine outflow

Question 130

USG of a dog

Answer 130

1.020-1.045

Question 131

USG of a cat

Answer 131

1.020-1.050

Question 132

Uraemia

Answer 132

a buildup of toxins in your blood. It occurs when the kidneys stop filtering toxins out through your urine. Clinical syndrome: Lethargy/depression Mucosal ulceration → oral, gastric Vomiting/diarrhoea Respiratory signs → uraemic pneumonitis, metastatic calcification Hypertension → can lead to hypertrophic cardiomyopathy Hypokalaemic myopathy (cats) → plantigrade stance, cervical ventroflexion Hyperkalaemic bradycardia → acute kidney injury & urinary obstruction Anaemia → non-regenerative

Question 133

Electrolyte disturbances in kidney disease

Answer 133

Sodium- Drops Chloride- Usually as per sodium, but can increase independently depending on the cause of the injury E.g. Fanconi’s syndrome Potassium AKI or urinary obstruction: Increases in all species → can be severe CKD: Dogs & horses: Increases Cats: Decreases → may need suplimentation Calcium Variable AKI: Increases CKD: Increases at first, then drops during end-stage failure Urinary obstruction: Drops - but we don’t know why! Phosphate Increases Magnesium Increases supplementation

Question 134

Metabolic acidosis

Answer 134

Occurs when acids start building up in the tissues/blood or when bases are lost If you retain acids → measurable with Anion Gap Ketones → DIABETES MELLITUS Lactate → INJURED OR HYPOXIC TISSUES Uraemic acids → RENAL INJURY HCl gets left behind if you have: SMALL INTESTINAL DIARRHOEA Specific types of RENAL TUBULAR INJURY (e.g. Fanconi’s Syndrome) HYPOADRENOCORTICISM (affects ion exchange in kidney)

Question 135

Metabolic alkalosis

Answer 135

Occurs when acid is lost Metabolic alkalosis causes: If you lose HCl: VOMITING → gastric secretions high in HCl TWISTED STOMACH (GDV) or DISPLACED ABOMASUM → HCl secreted into stomach but cannot enter small intestine to be resorbed → “lost” in the stomach Pyloric outflow obstruction (GASTRIC FOREIGN BODY) → as above GASTROINTESTINAL STASIS → as above

Question 136

Respiratory acidosis

Answer 136

Occurs when CO2 is not exhaled sufficiently CO2 is an acid → decreased exchange → build up of CO2 → acidosis Respiratory acidosis causes: Respiratory tract obstruction Pulmonary fibrosis Pulmonary thromboembolism Pulmonary neoplasia Pneumonia Anything that reduces O2/CO2 exchange… excess H+ H+ taken into tissue and exchanged for K+ → rise in blood K+

Question 137

Respiratory alkalosis

Answer 137

Occurs when CO2 is exhaled excessively Respiratory alkalosis causes: Tachypnoea CO2 is an acid → increased exhalation → alkalosis = H+ deficit H+ taken out tissue and exchanged for K+ → drop in blood K+

Question 138

causes of Mixed acid/base disorders

Answer 138

Renal failure with vomiting Renal failure = metabolic acidosis Vomiting = metabolic alkalosis Diabetic ketoacidosis and pancreatitis Ketoacidosis = metabolic acidosis Pancreatitis = metabolic acidosis +/- metabolic alkalosis (if there is vomiting) Septic abdomen (lactic acidosis) and hyperventilation Sepsis = metabolic acidosis Hyperventilation = respiratory alkalosis Vomiting causing aspiration pneumonia Vomiting = metabolic alkalosis Pneumonia = respiratory acidosis

Question 139

causes of Mixed acid/base disorders

Answer 139

Renal failure with vomiting Renal failure = metabolic acidosis Vomiting = metabolic alkalosis Diabetic ketoacidosis and pancreatitis Ketoacidosis = metabolic acidosis Pancreatitis = metabolic acidosis +/- metabolic alkalosis (if there is vomiting) Septic abdomen (lactic acidosis) and hyperventilation Sepsis = metabolic acidosis Hyperventilation = respiratory alkalosis Vomiting causing aspiration pneumonia Vomiting = metabolic alkalosis Pneumonia = respiratory acidosis

Question 140

Calcium & Phosphorous

Answer 140

Balanced controlled by PTH and Vitamin D Vitamin D less important in horses Excreted by the kidneys and absorbed by the intestines UV light for vitamin D production not applicable in veterinary species Dietary intake and balance important, especially in horses

Question 141

Calcium

Answer 141

Total calcium = bound to albumin and uraemic acids Total can increase or decrease with fluctuations in these negatively charged molecules → especially albumin Free (aka ionised) calcium = unbound calcium Levels very tightly controlled by PTH, vitamin D and calcitonin

Question 142

causes of hypercalcaemia

Answer 142

HARD IONS G Hyperparathyroidism → decreased excretion and increased bone resorption Addison’s disease → decreased excretion Renal disease → decreased excretion D-hypervitaminosis → psoriasis cream, rodenticide poisoning Idiopathic → most common cause in cats Osteolytic → osteosarcoma Neoplastic → PTHrp Spurious → artefact, analyser error Granulomatous disease → macrophages produce vitamin D

Question 143

hypocalcaemia

Answer 143

-Nutritional Insufficient dietary intake Excessive phosphorus intake Hypomagnesaemia -Renal Chronic: insufficient Vitamin D production- Not relevant in horses Acute: reduced tubular reabsorption Urinary tract obstruction: unknown -Pregnancy/lactation -Pancreatic pathology EPI: reduced vit D absorption Acute pancreatitis: unknown -Drugs/toxins Ethylene glycol Furosemide -Tissue injury Massive necrosis (e.g. in tumours) Rhabdomyolysis, polysaccharide storage myopathy Rumen overload: unknown

Question 144

Phosphorous

Answer 144

Increases: Decreased excretion- Renal injury (but not in horses!) Release from injured cells- Massive necrosis (e.g. in tumours) Rhabdomyolysis, polysaccharide storage myopathy Artefact with haemolysis or sample storage Excessive vitamin D Decreases: Increased excretion- Hyperparathyroidism Fanconi’s syndrome (dogs) Renal failure in horses Reduced intake Hypovitaminosis D

Question 145

Magnesium

Answer 145

Only rarely measured in practice. Has bound and unbound fractions like calcium. Most important aberrations: Increases with renal disease (reduced excretion) Decreases due to dietary deficiencies (aka staggers)

Question 146

Can I trust my results checklist

Answer 146

Is my analyser QC and calibration up to date? Do I know the grey zone for the analyte? Electrolytes have very small grey zone Hormones typically have ~20% variability in assay precision How reliable is my decision threshold? Check recent papers or textbooks for sensitivity and specificities Is the sample haemolysed/lipaemic/icteric? Check reagent inserts to work out if that analyte is affected Has my sample been taken/handled properly? Artefacts can occur if not stored properly Serum should be separated/spun soon after collection Gel in serum tubes can interfere with some tests e.g. progesterone Is this test fully sensitive/specific? Especially important with positive/negative results Consider further tests if: Result does not fit clinical picture E.g. FIV positive antibody test in a young indoor cat Sensitivity or specificity are not sufficient for a confident diagnosis E.g. Patient tests positive highly sensitive but poorly specific test Quantitative result required for confirmation or monitoring purposes E.g. SNAP cPLI/fPLI tests vs quantitative lipase measurement

Question 147

Haematopoiesis

Answer 147

formation of: Erythrocytes Leukocytes Platelets Typically occurs in the bone marrow but extramedullary haematopoiesis also occurs in the spleen and liver

Question 148

Clinical signs associated with disorders of the haemolymphoid system

Answer 148

Enlarged lymph nodes Anaemia Coagulopathies Oedema

Question 149

Bone marrow histology

Answer 149

Hematopoietic tissue is highly proliferative. Pluripotent hematopoietic stem cells (HSCs) are a self-renewing population, giving rise to cells with committed differentiation programs, and are common ancestors of all blood cells. Control of haematopoiesis is complex The dominant regulator of erythropoiesis is erythropoietin (Epo) produced by the kidney Iron is essential to haemoglobin formation and function Typically the bone marrow only releases mature cells, however in times of increased need, immature cells will be released into the blood stream Hence looking for polychromasia/reticulocytes in cases of anaemia to assess for regeneration And band neutrophils/left shift in inflammation/infection

Question 150

polychromasia/reticulocytes

Answer 150

Polychromasia occurs on a lab test when some of your red blood cells show up as bluish-gray when they are stained with a particular type of dye. This happens when red blood cells are immature because they were released too early from your bone marrow. These immature cells are called reticulocytes. Typically the bone marrow only releases mature cells, however in times of increased need, immature cells will be released into the blood stream

Question 151

neutrophils/left shift

Answer 151

when immature neutrophils are released from the bone marrow due to an outpouring of cells, typically due to infection. In any acute inflammation, an increase in neutrophils is often seen.

Question 152

Pancytopenia

Answer 152

defined as a complete lack of production of all lineages of haematopoiesis (bone marrow aplasia)

Question 153

diffusely enlarged spleen

Answer 153

Congested/bloody- Torsion Barbiturate euthanasia Acute haemolytic crisis African swine fever Septicaemia- Salmonella Anthrax Non-congested/firm/meaty Neoplasia- Lymphoma Mast cell tumour (cats) Chronic immune-mediated haemolytic anaemia Chronic infection- Mycoplasma, etc Chronic inflammation

Question 154

Benign spelnic masses

Answer 154

Nodular hyperplasia Haemangioma Haematoma

Question 155

Indolent splenic masses

Answer 155

Marginal zone lymphoma

Question 156

Malignant splenic masses

Answer 156

Haemangiosarcoma Histiocytic sarcoma

Question 157

Histiocytic neoplasia

Answer 157

Histiocytes are a subset of leukocytes Originate from CD34 stem cells Types: Macrophages Dendritic cells (histiocytic sarcoma) Langerhan’s cells (histiocytoma) Blood monocytes Benign - Histiocytoma Skin Young dogs and Boxers Spontaneously regress Malignant Histiocytic sarcoma Burnese Mountain Dogs, Flat Coated Retrievers, Rottweilers Can be localised, often around joint, or systemic involving the spleen Also, several slightly bizarre reactive histiocytic syndromes Malignant histiocytosis (Burnese mountain dogs) Pulmonary Langerhans cell histiocytosis (cats)

Question 158

The urinary filtration barrier comprises

Answer 158

Fenestrated endothelium of glomerular capillaries Glomerular basement membrane Foot processes of the podocytes The filtration barrier is selectively permeable Under normal circumstances, all cellular components and plasma proteins the size of albumin or larger are retained in the bloodstream. Water and solutes are freely filtered. Molecular charge is also important.

Question 159

Renin-angiotensin-aldosterone system

Answer 159

Renin Released by juxtaglomerular apparatus in response to low blood pressure and flow to the kidney Transforms angiotensinogen (made by the liver) to angiotensin I Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE – made by the lung) Angiotensin II Acts directly on vessels to result in vasoconstriction-> increase blood pressure Acts on the adrenal gland to produce aldosterone-> kidney tubules resorb salt and water

Question 160

Hydronephrosis

Answer 160

refers to dilation of the renal pelvis, which fills within urine. Typically due to downstream blockage Increased pressure in the renal pelvis results in no where for urine to go and glomeruli continue to “make” urine-> urine is forced into renal interstitium -> collapse of interstitial vessels -> hypoxia  -> repair by fibrosis

Question 161

pathophysiology

Answer 161

the study of structural and functional changes in tissue ans organs in the disease state

Question 162

Uraemia

Answer 162

The systemic changes associated with severe azotaemia Uraemia is a clinical syndrome Whilst in clinical pathology we associate elevated levels of urea and creatinine with renal failure, in reality, over 90 toxins that would otherwise be filtered by the kidney build up in the blood Uraemic toxins damage tissue by Endothelial damage Also, some of these toxins are leached into saliva and gastric secretions-> metabolised to ammonia -> caustic ulceration of mucosa (tongue, stomach, colon) Animals with chronic renal failure are azotaemic and will eventually become uraemic

Question 163

Chronic renal failure

Answer 163

When one part of the nephron is damaged, eventually the rest of the nephron follows Replaced by fibrosis Animals with chronic renal failure are azotaemic and will eventually become uraemic Other findings: Hypertension Non-regenerative anaemia Hypokalaemia Calcium deposition in soft tissues

Question 164

role of the kidney with calcium

Answer 164

The role of the kidney is three-fold Resorption of calcium Phosphate excretion Activation of vitamin D Failing kidneys result in - Reduced calcium Increased phosphate Inactivated vitamin D Less calcium absorbed from intestine Chronic renal failure ultimately results in renal secondary hyperparathyroidism Due to low calcium, the parathyroid glands become hyperplastic and produce more parathyroid hormone As there is no other way in the animal of increasing plasma calcium, calcium is resorbed from bone This results in weak bones, replaced by fibrosis = rubber jaw Also the combination of high phosphate and acidosis means calcium is deposited in soft tissues, particularly stomach, kidney and pleura

Question 165

Renal dysplasia

Answer 165

Progressive juvenile nephropathies Polycystic kidney disease

Question 166

Neoplasia of the kidney

Answer 166

From within – typically unilateral and singular Renal cell carcinoma Urothelial cell carcinoma From without – typically bilateral and multiple Lymphoma

Question 167

Endocrinopathies are due to

Answer 167

An under or overproduction of hormones An inability to respond to hormone production. Exogenous hormone administration. Production of hormone-like substances from certain cancers Underproduction of hormones is due to Immune-mediated destruction of the endocrine organ. Upstream endocrine organ destruction. The inability to produce a hormone due to a nutritional deficiency. Typically, overproduction is due to hyperplasia or neoplasia.

Question 168

Neurohypophysis (posterior pituitary, pars nervosa):

Answer 168

Oxytocin ADH (antidiuretic hormone/vasopressin)

Question 169

Adenohypophysis (anterior pituitary)

Answer 169

Pars distalis: Lactotrophs (acidophils): PRL (prolactin) Somatotrophs (acidophils): GH (growth hormone), Thyrotrophs (basophils): TSH (thyroid-stimulating hormone) Gonadotrophs (basophils): FSH (follicle-stimulating hormone, LH (luteinizing hormone) Corticotrophs (chromophobes): ACTH (adrenocorticotrophic hormone) Pars tuberalis: Scaffold for the capillary network of the hypophyseal portal system; has secretory granules, stellate cells, and receptors for melatonin Pars intermedia: Melanotrophs: MSH (melanocyte-stimulating hormone), b-endorphin, and corticotropin-like intermediate lobe peptide (CLIP)

Question 170

Clinical Categories of Laminitis

Answer 170

Multifactorial disease process, with common end-point of laminar degeneration Endocrinopathic- Insulin dysregulation (Equine Metabolic Disease) Equine Pituitary Pars Intermedia Dysfunction (PPID) 80% of cases of laminitis have underlying endocrinopathic disorders Inflammatory Severe infection (sepsis, colitis, endometritis) Traumatic Excess weight bearing on one limb (contralateral limb laminitis)

Question 171

Pituitary pars intermedia dysfunction

Answer 171

Age related degenerative condition Loss of dopaminergic inhibition Hypothalamus unable to regulate pars intermedia of pituitary gland Hypertrophy / hyperplasia of PI Increase production of many hormones from PI which have wide array of effects on body Increase gluconeogenesis Decrease glucose utilisation Increase glycogen deposition in liver Decrease protein synthesis in muscles Increase fat breakdown and redistribution Decrease production and function of WBCs (immunosuppression) Decrease cell division Increase gluconeogenesis Decrease glucose utilisation Increase glycogen deposition in liver Decrease protein synthesis in muscles Increase fat breakdown and redistribution Decrease production and function of WBCs (immunosuppression) Decrease cell division

Question 172

SMEDI

Answer 172

Still birth, mummification, embryonic death and infertility In the pig is classic for parvovirus

Question 173

Maceration of the foetus

Answer 173

When a fetus dies in utero, there are changes in the skin and tissues—termed fetal maceration. This process takes place entirely in the womb and stops once the fetus is delivered Foetus is liquified Foetid smell Bones will remain Bacterial cause Endometritis Open cervix

Question 174

Emphysema in the foetus

Answer 174

A disorder affecting the alveoli (tiny air sacs) of the lungs. The transfer of oxygen and carbon dioxide in the lungs takes place in the walls of the alveoli. In emphysema, the alveoli become abnormally inflated, damaging their walls and making it harder to breathe. Associated with Protracted dystocia Late expulsion of dead foetus Putrefactive ascending bacteria e.g. clostridial organisms) Foul smell and gas under skin (crepitant) Advanced uterin lesions and dam may die due to toxaemia

Question 175

how can lepto be diagnosed from the foetus

Answer 175

Foetal kidney PCR for lepto

Question 176

how can chlamydia be diagnosed form the foetus

Answer 176

MZN stain of foetal stomach content or PCR for chlamydia

Question 177

what can be cultured from foetal stomach content

Answer 177

Salmonella and other bacterial and fungal contents

Question 178

what is tested for in occult instanses of abortion

Answer 178

Salmonella and other bacterial and fungal contents can be cultured from foetal stomach content Chlamydia and lepto difficult to culture so MZN stain of foetal stomach content or PCR for chlamydia Foetal kidney PCR for lepto Coxiella also tested for with MZN before proceeding with sheep abortions due to zoonotic risk Brucella testing to maintain Brucella-free testing also MZN Histopathological +/- IHC of foetal tissues- Brain, liver, lung AND PLACENTA Serology – dam blood and foetal fluid

Question 179

Perinatal mortality

Answer 179

may be defined as death of the foetus or perinate before, during or within 48 h of calving at full term (> 260 days in cattle) Includes both stillbirth and early neonatal mortality As well as the previously discussed samples, examination of the foetal thyroid gland for absolute goitre (thyroid enlarged relative to a criterion-referenced threshold thyroid weight, e.g. > 30 g) or relative goitre (thyroid enlarged relative to a criterion-referenced threshold thyroid g: kg ratio with body weight, e.g. > 0.80) and submission of a fresh (I2 content) and formalinised lobe (histopathology) will detect dietary iodine imbalance. Where selenium deficiency is suspected a fresh sample of the foetal liver preferably or kidneys should be submitted.

Question 180

what samples do you take from a still birth

Answer 180

Fresh tissues: lung, liver, kidney, thymus (viral PCR), stomach contents,other foetal fluid, placenta Fixed tissues: lung, liver, kidney, thymus, placenta, brain, spleen, heart, thyroid, adrenal, skeletal muscle

Question 181

Cysts that occur within the ovarian parenchyma include cysts derived from

Answer 181

anovulatory Graafian follicles (luteal and follicular cysts) cystic corpora lutea cystic rete ovarii- The rete ovarii, the homolog of the rete testis, is present in the hilus of all ovaries. cysts of the subsurface epithelial structures Luteal and follicular cysts both are derived from anovulatory Graafian follicles and differ only in the degree of luteinisation- During normal proestrus, regression of the CL coincides with development of a selected follicle, while the growth of any additional follicles is inhibited. In animals developing COD, ovulation fails to occur and the dominant follicle continues to enlarge. Cysts derived from anovulatory Graafian follicles are most common in the cow and sow, but also occur sporadically in the bitch and queen. They often cause altered reproductive activity through secretion of steroid hormones. Affected animals, especially bitches, may show marked manifestations of hyperestrinism, such as altered reproductive behavior, anemia, and hemorrhagic diathesis. In the cow and sow they may be associated with anestrus, persistent estrus, or nymphomania Cystic corpora lutea are essentially a variation of a normal luteal structure and the animal may be pregnant.

Question 182

Taylorella equigenitalis

Answer 182

CEM, caused by Taylorella equigenitalis, a microaerophilic gram negative coccobacillus, is a highly contagious venereal disease of mares that is characterized by endometritis, transient infertility, and rarely abortion Stallions do not develop clinical disease, but can transmit the organism; recovered mares can harbour the organism for several months and are an important reservoir Infectious endometritis – similar clinical, gross, and histologic changes; bacteriologic culture to differentiate

Question 183

Endometrial hyperplasia

Answer 183

is common in domestic canines, often involves cystic distension of endometrial glands (cystic endometrial hyperplasia, CEH). Exogenous sources of progesterone can be found in megestrol acetate, etc. Chronically hyperplastic endometrial glands lead to the gross accumulation of mucoid fluid = mucometra and hydrometra There is debate among authors whether cystic endometrial hyperplasia (CEH) and pyometra are linked, it is currently thought that prolonged exposure to high levels of progesterone cause endometrial gland proliferation which may increase susceptibility of the uterus to infection. E.coli

Question 184

Uterine endometrial adenocarcinoma

Answer 184

The most common neoplasia of the rabbit reproductive tract and probably the most common neoplasia of any body system of female rabbits Carcinoma = malignant 80% will metastasize lungs

Question 185

Leiomyoma/leiomyosarcoma

Answer 185

Tumour of smooth muscle Leiomyomas of genital origin are among the most frequently encountered neoplasms of the female reproductive system in almost all domestic animals, including elephants

Question 186

Severe necrotizing/gangrenous Mastitis

Answer 186

Gram –ve bacteria Endotoxin production ->Massive cytokine release -> necrosis -> increase in vascular perm Wet gangrene Quarter may slough Sick cow

Question 187

Granulomatous Mastitis

Answer 187

Contamination of teat-administered drugs are contaminated Nocardia Cryptococcus Atypical Mycobacteria Candida

Question 188

Viral mastitis in goats

Answer 188

Caprine arthritis and encephalitis (CAEV) Retrovirus Indurative mastitis Hard udder Pathogenesis Not fully understood. Virus-infected macrophages in colostrum and milk are absorbed intact through the gastrointestinal mucosa. Spread throughout the body via infected mononuclear cells. Periodic viral replication and macrophage maturation induce massive lymphoproliferative lesions in target tissues and organs such as the lungs, synovium, choroid plexus, and udder. Persists by residing as provirus within host cells

Question 189

Fibroadenomatous hyperplasia

Answer 189

Cats Young intact females Progesterone a non-neoplastic, benign condition that is seen most often in young, intact female cats. This lesion is associated with prolonged progesterone or other hormonal exposure, via endogenous or exogenous sources

Question 190

Dogs – herpes virus

Answer 190

More commonly causes death of puppies <2weeks old. Herpes virus is latent in the bitch causing no to minimal clinical signs but recrudesces during late pregnancy. Some adults will have ocular and/or vaginal discharge. Puppies are infected during birth. Viraemia as virus spread via macrophages. Incubation period 6-10 days. Puppies are anorexic, hypothermic, vocal, disorientated. Fading puppies? Most if not all of litter will die. Optimum temperature for replication of the virus is 34-36c, hence (partly) why neonates are worse affected, and active warming can improve prognosis. Gross lesions include bilateral, multifocal, petechial and ecchymotic haemorrhages of the kidneys and liver. Necrosis in kidneys, liver and lungs. Typical intranuclear viral inclusion bodies. Virus, like a lot of herpesviruses, is endotheliotropic so most lesions are typically due to death of endothelial cells resulting in damage to blood vessels. Herpes virus is not a core vaccine, but can be given to breeding bitches at request BEFORE and during pregnancy

Question 191

Dogs – Brucella canis

Answer 191

Zoonotic Transmitted primarily through mating to the bitch then to puppies in utero and milk. Abortion mid pregnancy due to placentitis and endometritis, and aborted material source of infection. Female may continue to shed bacteria intermittently for weeks to months. Aborted foetuses may have renal haemorrhages but bronchopneumonia most typical. If mated again, subsequent pregnancies may reach full term but neonates may be weak or die. In the male, it causes infertility and epididymitis. Dogs with no clinical signs can still be infectious. Discospondylitis common clinical presentation. Testing methods include bacterial culture of any fluid from an adult/foetus and some practices are now offering serology for any imported animal prior to surgery.

Question 192

Cats – feline panleukopenia virus

Answer 192

Parvovirus Faeco-oral spread Requires infection of rapidly dividing cells to replicate- GIT Bone marrow Early in utero infection: Foetal death and resorption Perinatal infection 2 wks prenatal - 2 wks postnatal Infection of cerebellum at crucial developmental period cerebellar hypoplasia -> ataxia 2-4 months postnatal Infection of bone marrow, thymus, GIT and mucosal lymphoid tissue Leukopenia and enteritis 4-12months Enteritis

Question 193

what is desribed in descriptive pathology of the bovine placenta

Answer 193

Chorioallantois not amnion *Size and number of cotyledons (range 72-125) *Freshness: smell, colour, texture *Cotyledons: red, pale, necrotic, exudate; fibrin/pus *Intercotyledonaryareas:thickened/’plaques’, exudate; fibrin/pus

Question 194

what is desribed in descriptive pathology of the aborted calf

Answer 194

Freshness: smell, colour of viscera (all similar after 24-48hr death in utero) *Size, weight, crown rump length, features of development *Skin lesions, covered with exudate, meconium *Excess fluid in body cavities: clear, pink, red, fibrin *Stomach content: meconium

Question 195

what is desribed in descriptive pathology of the bovine organs

Answer 195

*Lungs –inflated (pink, spongey) or not (atelectic; dark pink/red) *Liver –haemorrhages, multifocal lesions, abnormal size/shape/structures*Intestine –atresia (colon, rectum, etc), inflammation/necrosis *Kidney –number, structure *Heart–size,shape,anatomy *Musculoskeletal and others–‘describe whatyousee’

Question 196

what is desribed in descriptive pathology of the bovine brain

Answer 196

Size and structure, abnormalities? *Cavitation of cerebral hemispheres: hydranencephaly, porencephaly *Cerebellar hypoplasia

Question 197

what samples are taken from an abortion in the calf

Answer 197

*Aborted calf (if suitable) *Placenta *Maternal blood? *Bulk milk? *Cohort bloods? *Faeces, environmental samples, etc? Calf samples *Fresh- *Stomach content (liver or lung if unavailable)- Bacteriology, fungal examination *Spleen or thymus- PCR pestivirus *Kidney-PCR Leptospires *Foetal fluid-Antibody tests *Brain-Weigh, iodine *Thyroid (stillborn) Adrenal or liver- PCR BoHV-1 *Fixed: Lung, brain, liver, heart, + stomach wall, eyelid Placental samples*Fixed and fresh cotyledon

Question 198

pathology of Chlamydia abortus: Enzootic abortion on sheep placenta

Answer 198

inflamed cotyledons/ intercotyledonary *Thick necrotic exudate

Question 199

pathology of Toxoplasma gondii: toxoplasmosis abortion on sheep placenta

Answer 199

*Inflamed cotyledons with necrotic foci → totally necrotic cotyledons- straberry cotelydons *Little/no intercotyledonaryreaction *Non specificfoetalpathology *Fresh →mummies

Question 200

pathology of Campylobacteriosis on sheep placenta

Answer 200

Lambs: non specific → multifocal hepatitis *Placenta –pale/small necrotic cotyledons Campylobacter fetus fetus *Campylobacter coli/jejuni

Question 201

equipmetn for horse abortion PM

Answer 201

Scales (up to ~100kg, and grams -10kg) *Measuring tape *PM knife or scalpel *(Sterile scalpel) *Rat tooth forceps *(Sterile forceps) *Universal containers –2 *Formalin and suitable pots *Charcoal swabs –3 *Gas burner *SpatulaOr *1/2 swabs and 1/2 extra universal containers/60ml pots

Question 202

CRL

Answer 202

generally used to assess gestational age crown-rump length

Question 203

Samples for virology (PCR)

Answer 203

thymus lung liver spleen kidney all in one container 4 small pieces of chorioalatous in another pot

Question 204

samples for bacteriology

Answer 204

*Liver(or heart blood if liver too soft)- this is done by heating a scalple, searing the flesh, cutting into the steralised area andusing a charcole swab to collect a sample from the cut *Lung (or stomach content) *Chorioallantois- the swab from here shoul be taken from the cervical pole, which is an area aound the cervical scar

Question 205

samples for histology

Answer 205

*Liver–4 small samples ~1-2 cm cubed *Lungs–4 small samples from different lobes *Spleen *Adrenal gland *Kidney–wedge from centre of each kidney (cortex to pelvis) *Thymus *Conjunctiva *Thyroid *Heart *Chorioallantois –5 samples –see later *Amnion –2 samples *Umbilical cord –2 cm section*Any abnormal findings should be sampled

Question 206

Amniotic plaques

Answer 206

Amniotic plaques are commonly observed in the placenta of cattle as well as other species. These plaques are 2–4 mm in diameter [28]. They typically appear as a slightly raised annular lesion that histologically appears as a proliferation of hyperplastic epithelium that often shows squamous metaplasia. normal

Question 207

what preservative should samples for histopathology be routinely collected?

Answer 207

Formalin

Question 208

Which additional histochemical stain is used to highlight mycobacteria in histopathological sections?

Answer 208

Ziehl-Neelsen / ZN

Question 209

What process visible via light microscopy will differentiate between autolysis and necrosis?

Answer 209

Inflammation or lack of inflammation

Question 210

Blood samples for performing haematology should be collected into tubes containing which anticoagulant?

Answer 210

EDTA

Question 211

Which benign round cell tumour is most common in the skin of young dogs and regresses spontaneously following T-cell infiltration?

Answer 211

Histiocytoma

Question 212

embolic nephritis

Answer 212

inflammation of a specific segment of glomeruli, which is associated with subacute bacterial endocarditis, and frequently produces microscopic hematuria without azotemia

Question 213

Which baterial agent is the most common cause of cystitis in dogs?

Answer 213

Escherichia coli or E. coli

Question 214

Darkfield microscopy is typically used to diagnose which infectious disease of the kidney?

Answer 214

Leptospirosis

Question 215

Which basal endocrinology test can be used to diagnose canine hypoadrenocorticism?

Answer 215

Cortisol

Question 216

arthrogryposis.

Answer 216

term used to describe a variety of conditions involving multiple joint contractures (or stiffness). A contracture is a condition where the range of motion of a joint is limited in the fetus its a sign of schmallenberg

Question 217

The combination of still birth, mummification, embryonic death and infertility primarily in primiparous sows is most indicative of which infectious agent?

Answer 217

Parvovirus

Question 218

What is the most common non-odontogenic oral neoplasm in dogs?

Answer 218

Melanoma/malignant melanoma

Question 219

Mucosal mineralisation of the stomach is typically due to failure of which organ?

Answer 219

Kidney/renal/urinary

Question 220

Which equine parasite undergoes hypobiosis in the large intestine, resulting in severe disease upon emergence?

Answer 220

cyathostomins/small strongyles

Question 221

Define pre-patent period in the context of gastrointestinal parastiology.

Answer 221

Time between infection and oocyst/egg shedding in the faeces

Question 222

Cirrhosis

Answer 222

Cirrhosis is scarring (fibrosis) of the liver caused by long-term liver damage. The scar tissue prevents the liver working properly. Cirrhosis is sometimes called end-stage liver disease because it happens after other stages of damage from conditions that affect the liver, such as hepatitis.

Question 223

Nutmeg liver is typically secondary to failure of which other organ or tissue?

Answer 223

Heart/cardiac

Question 224

EHV abortion

Answer 224

Markedly increased clear yellow fluid, thorax and pericardium *Jaundice- multifocal hepatic necrosis Thymic necrosis –*colourchange from pink to cream-tan *liquefaction Pulmonary consolidation*Intranuclear inclusion bodies in hepatocytes

Question 225

EHV-4

Answer 225

▪Usually sporadic cases▪Usually have excess of body fluids ▪Liver / lung lesions –sparse or absent ▪Spleen –best site for virus isolation ▪Many lesions secondary to hypoxia (alive foals may survive)

Question 226

Hypospadia

Answer 226

Due to failure of the urogenital groove to close in the male

Question 227

Tumours of the testicle

Answer 227

Interstitial/Leydig cell tumour Seminoma Sertoli cell tumour

Question 228

Tumours of the scrotum

Answer 228

Vascular hamartoma, haemangioma and haemangiosarcoma Melanoma Mast cell tumour

Question 229

– Sertoli cell tumours

Answer 229

Grossly: The tumours are white Irregularly ovoid Lobulated Bulge when cut May be cystic Abundant fibrous stroma makes then firm to hard May cause marked distortion of the testicle Most are benign The incidence of Sertoli cell tumours is 20 times higher in cryptorchid dogs Up to 30% of affected dogs produce excessive oestrogen, resulting in: Feminization, including attraction of male dogs Reduced libido Testicular and penile atrophy Preputial swelling Perineal hernia Gynecomastia Redistribution of fat Symmetrical, often ventral, alopecia. Squamous metaplasia of the prostate gland (see later slide) Oestrogenic depression of bone marrow can result in- Anaemia Thrombocytopenia Granulocytopenia

Question 230

Any defect, injury or infection, that results in leakage of spermatozoa or spermatozoal antigens into the extra tubular compartment results in...

Answer 230

a foreign body or granulomatous response, fibrosis, continued disruption of tubules, spermiostasis, or spermatocele Innate and acquired immune function is actively suppressed in testicular parenchyma, as spermatocytes, spermatids, and spermatozoa are highly antigenic and outside the blood-testis barrier

Question 231

Infections of the testicle and epididymis

Answer 231

Orchitis and epididymitis Sheep Brucella ovis Orchitis: Sheep/Goat pox virus, Visna/maedi virus, Trueperella pyogenes, Corynebacterium pseudotuberculosis, Brucella melitensis, Histophilus ovis Epididmytis: Actinobacillus seminis (most important); Histophilus somni, Mannheimia haemolytica, E.coli, Trueperella pyogenes Pigs- Brucella suis Cattle- Brucella abortus Orchitis: Mycobacterium bovis, M. tuberculosis, E. coli, Proteus vulgaris, Corynebacterium ovis, Streptococcus , Staphylococcus sp., Trueperella pyogenes, Actinobacillus spp, Nocardia farcinica, Chlamydia spp,, and Mycoplasma sp Epididymitis: bovine herpesvirus 4 (cytomegalovirus), Actinobacillus seminis, Mycoplasma bovigenitalium, Trypanosoma brucei Dogs- Brucella canis Cats- Naturally resistant to Brucella Orchitis: FIP Epididymitis is rare Scrotal inflammation Chorioptes bovis-> scrotal mange in SHEEP

Question 232

Diseases of the prostate - prostatitis

Answer 232

Typically ascending E.coli common Abscessation and sepsis Benign prostatic hyperplasia is the most common disorder of the prostate in intact males Under the influence of testosterone the prostate will become hyperplastic Is symmetrical May not cause issue but is palpable on rectal exam Clinical signs include haematuria and preputial discharge May be cystic Resolves post castration prostatic squamous metaplasia- due to excess oestrogen via unknown pathogenesis The excess oestrogen in this case would be from a Sertoli cell tumour

Question 233

Metaplasia

Answer 233

the change from one differentiated cell type to another of the same germ layer. In this case is from cuboidal epithelium in gland formation to stratified squamous In the normal animal the change from specialised epithelia to strat. squamous is protective

Question 234

neoplasia of the prostate

Answer 234

Carcinoma as epithelial and typically malignant In the dog, arise more commonly from the urothelial tissue in the urethra= urothelial cell carcinoma (transitional cell carcinoma) Less commonly arise from the glandular parenchyma= prostatic adenocarcinoma - more common in humans and a mouse model

Question 235

Posthitis

Answer 235

inflammation of the prepuce

Question 236

Balanoposthitis

Answer 236

inflammation of the glans penis

Question 237

Phalitis

Answer 237

inflammation of the entire penis

Question 238

Phalophosthitis

Answer 238

inflammation of both penis and prepuce

Question 239

Pizzle rot

Answer 239

Posthitis in sheep Corynebacterium renale

Question 240

Bovine herpes virus 1

Answer 240

Phaloposthitis in the bull Infectious pustular vulvovaginitis and abortion in the cow (see dry lab) Respiratory disease in the calf

Question 241

neoplasm of th epenis and prepuce

Answer 241

Papillomas Genital papillomas, or warts, on the penis seen in horses and cattle Viral cause In horses can progress to squamous cell carcinoma Melanoma

Question 242

Volvulus

Answer 242

occurs when a loop of intestine twists around itself and the mesentery that supplies it, causing a bowel obstruction. Symptoms include abdominal distension, pain, vomiting, constipation, and bloody stools. The onset of symptoms may be insidious or sudden.

Question 243

Hyperaemia

Answer 243

he process by which the body adjusts blood flow to meet the metabolic needs of its different tissues in health and disease

Question 244

general pathological apearence of intestines with acute infection

Answer 244

Hyperaemia Fluid filled lumen

Question 245

Enterotoxaemia

Answer 245

bacterial toxins absorbed into bloodstream from intestines Typically in veterinary species we are referring to various types of Clostridium perfringens Types A to E All produce a different of combination of toxins Type D produces epsilon toxin Typically seen in fat weaned lambs after sudden diet change/increase in grain = overeating disease Pore forming Enterocyte necrosis Necrohaemorrhagic enteritis Kidney tubular cell necrosis “pulpy kidney” glucosuria Increases vascular permeability Petechial haemorrhages Pericardial effusion Brain oedema -> neurological signs Blindness, headpressing, ataxia

Question 246

viruses in the GIT tract

Answer 246

Most viruses generally prefer to infect cells with rapid turnover as can use their replicative mechanisms to produce more virus GIT has constant cell turnover Most viruses generally prefer to infect cells with rapid turnover as can use their replicative mechanisms to produce more virus GIT has constant cell turnover Some viruses take this one step further and stimulate prolific growth e.g. papilloma viruses Stimulate the cell cycle In some cases inhibit innate cell-mediated immunity Hyperplastic lesions -> papilloma (and sarcoids) Malignant transformation in some cases Squamous cell carcinoma Cervical carcinoma in humans Due to purpose of the GIT, viral shedding and therefore infectivity is high Faeco-oral transmission Saliva Many viruses of significant veterinary importance spend all if not most of their transmission cycle within the GIT

Question 247

Erosion

Answer 247

Loss of the superficial surface epithelium but basement membrane/lamina propria intact

Question 248

Ulceration

Answer 248

Loss of surface epithelium and extends into lamina propria/submucosa

Question 249

Vesicle

Answer 249

Fluid filled space between layers of the epithelium Blister Also common in auto-immune diseases

Question 250

Pustule

Answer 250

As per vesicle but contains necrotic material/pus

Question 251

motility issues in the GIT

Answer 251

Ileus = arrest of intestinal motility in the absence of an obstruction Clinical signs Colic Distension Reflux/regurgitation Vomiting Neuropathic Myasthenia gravis (more later) Inflammation Ileus common post surgery and stress rabbits

Question 252

metabolic causes of pathology in the GIT

Answer 252

Non GI causes of vomiting Uraemia Neurological Addison’s Hypoadrenocorticism Intermittent v+d+ Glucocorticoids maintain normal gastrointestinal mucosal integrity and function Intestinal epithelial barrier disruption leads to permeability defects and the subsequent interaction of intestinal immune cells with the luminal contents. Activated immune cells release pro-inflammatory cytokines, such as TNF. In turn, TNF results in tight junction (TJ) disruption and intestinal epithelial cell (IEC) apoptosis and thereby exacerbates local inflammation. TNF also directly stimulates IECs to synthesize and release immunoregulatory glucocorticoids (GCs) to counter-balance excessive tissue damage. GCs act via the glucocorticoid receptor (GR) to inhibit TNF-mediated tissue damage in a negative feedback loop. The GR also inhibits pro-inflammatory transcription factors, including NF-κB, AP-1, and STATs leading to the resolution of the inflammation.

Question 253

FELINE CHRONIC GINGIVOSTOMATITIS (FCGS)

Answer 253

Presents as severe inflammation of the oral cavity * Most commonly affects the caudal oral mucosa: - palatoglossal arches (fauces), - alveolar and buccal mucosa of the caudal oral cavity, - less commonly soft palate and dorsal aspect of the caudal tongue * The hard palate, labial mucosa and sublingual mucosa are usually spared * Not fully understood – probably several factors: - Dental and periodontal disease, - Altered immunological response, - Infections: - feline calici virus, - FeLV, FIV, feline herpes virus-1, - Pasteurella multocida, Bartonella spp., Mycoplasma felis … * Usually affects adult cats * Extremely painful * Diminished food intake * Weight loss * Ptyalism * Halitosis * Unkempt appearance May be bippsied to distinguish from squamous cell carcinoma (SCC)- * Marked lymphoplasmacytic inflammation with prominent numbers of plasma cells * Localised to the mucosa, but can extend into the submucosa (occasionally also sialadenitis, myositis) * Mott cells = plasma cells with numerous globular cytoplasmic inclusions composed of immunoglobulin (Russell bodies) * Hyperplasia and erosion of overlying epithelium * Migration of neutrophils into the epithelium * Variable numbers of macrophages, mast cells

Question 254

Ptyalism

Answer 254

a condition where you make too much saliva.

Question 255

Mott cells

Answer 255

plasma cells with numerous globular cytoplasmic inclusions composed of immunoglobulin (Russell bodies) ssociated with stress conditions occurring in a number of conditions including chronic inflammation, autoimmune diseases, lymphomas, multiple myeloma, and Wiskott–Aldrich syndrome

Question 256

Russell bodies

Answer 256

eosinophilic spherical or globular cytoplasmic inclusions that accumulate in the rough endoplasmic reticulum of mature plasma cells. These plasma cells containing Russell bodies are also known as Mott cells

Question 257

EOSINOPHILIC GRANULOMA COMPLEX (EGC)

Answer 257

* In cats, it affects a broad age and breed range with common sites being: - dorsal surface of the tongue, - palate, - mucocutaneous junction of the rostral lips In dogs, it is over-represented in Siberian huskies and Cavalier King Charles spaniels with common sites being: - palate, - less commonly tongue, lips, other mucosal sites A complex of inflammatory diseases that represents a group of similar hypersensitivity reactions to various antigens (environmental, ingested materials, parasitic) * Several clinical presentations/terms: - linear granuloma, - eosinophilic plaque/granuloma, - collagenolytic granuloma, - indolent ulcer histopathology- * Variable numbers of eosinophils (can be a mixed inflammatory population with eosinophils) * ↑ neutrophils in ulcerated areas * Collagenolysis- The proteolytic processing of collagen * Cytology can often provide a diagnosis, so histology is not necessarily needed The pathologist provides a diagnosis of eosinophilic or mixed inflammation with eosinophils * In highly indicative cases (based on histology and clinical history), the pathologist can mention EGC in the commen

Question 258

OSTEOMYELITIS of the mouth

Answer 258

* The source of infection can be: - hematogenous (bacteraemia), - implantation (open jaw fractures, contamination of surgical sites, bite wounds, gunshot wounds), - local extension (from an infected tooth or periodontal tissues) * Common infectious agents are: - Staphylococcus spp., - Streptococcus spp., - Truperella pyogenes, - Nocardia spp., - Coccidioides immitis, - Cryptococcus neoformans Osteomyelitis and destructive malignant neoplasms can have a similar appearance! * Several things need to be taken into consideration: - clinical examination, - diagnostic imaging, - histology, - microbiology

Question 259

SQUAMOUS CELL CARCINOMA (SCC) in the oral cavity

Answer 259

* The most common non-odontogenic oral neoplasm in cats * Can present as a proliferative, ulcerated lesion or a non-healing wound * Often invades underlying bone * Can metastasize, but usually later on * Can mimic osteomyelitis on X-ray! The 2 nd most common nonodontogenic oral neoplasm in dog histopathology- Keratin pearls- neoplastic keratinised squamous cells forming concentric layers * Neoplastic cells in SCC extend past the basement membrane into the underlying stroma * The majority of them is either well or moderately differentiated * Dysplastic changes of the epithelium may possibly evolve into SCC

Question 260

CANINE CHRONIC ULCERATIVE (GINGIVO)STOMATITIS (CCUS)

Answer 260

* Lesions most often occur on the buccal mucosa and lateral lingual mucosa opposite to larger tooth surfaces * Affected mucosa is often depigmented and mirrors the shape of the associated tooth → contact stomatitis * Predisposed breeds: greyhound * Poorly understood, most likely due to inflammatory reaction to persistent plaque bacterial biofilm that damages the mucosa * Clinical signs: - drooling, - halitosis, - reluctance to eat histopathology * Lichenoid and perivascular infiltrate of B and T lymphocytes and plasma cells * Often ulcerated epithelium, intercellular oedema, transmigration of neutrophils and T lymphocytes and sparse necrotic/apoptotic epithelial cells * Granulation tissue formation beneath ulceratio

Question 261

Lichenoid infiltration

Answer 261

a bandlike infiltrate of inflammatory cells in the superficial dermis, parallel to the epidermis

Question 262

perivascular infiltrate

Answer 262

Inflammatory cells are clustered around blood vessels

Question 263

MALIGNANT MELANOMA

Answer 263

* The most common non-odontogenic oral neoplasm in dogs * Mean age: 10.5 – 12 years * Early and high metastatic rate * Often invades underlying bone (50%) * Very rare in cats * Melanocytoma, benign neoplasm of melanocytic origin, is very rare in the oral cavit histopathology- * MI > 4/10 HPF  * ↑ nuclear atypia  * Ki67 > 19.5  * ↓ pigmentation  Amelanotic MALIGNANT MELANOMA- * Immunohistochemistry: - Melan A - PNL2 (slightly ↑ sensitive than Melan A) may metastisise

Question 264

FIBROSARCOMA

Answer 264

* The 3rd most common non-odontogenic oral neoplasm in dogs * Mean age: 8 years * Maxillary and palatal lesions are more common than mandibular * Locally aggressive, invasive and destructive * Low metastatic rate * The 2nd most common malignant oral neoplasm in cats (after SCC) histology to distinguishe Fibrosarcoma from amelanotic malignant melanoma * Final diagnosis with IHC: - vimentin + - Melan A - - PNL2 -

Question 265

Canine biologically high-grade/histologically low-grade FIBROSARCOMA (H/L FSA)

Answer 265

Most often arises from the maxillary gingiva * Most frequent in large breed dogs, especially Golden retrievers * Biologically very aggressive histopathology- * Very bland histology reminiscent of fibrous connective tissue * Histopathology cannot distinguish between H/L FSA and fibrous gingival hyperplasia or fibroma * Clinicopathological correlation is VITAL!

Question 266

FIBROMATOUS EPULIS OF PERIODONTAL LIGAMENT ORIGIN (FEPLO)/PERIPHERAL ODONTOGENIC FIBROMA (POF

Answer 266

* A common most likely reactive gingival lesion * Mean age: 8.5 years * Rostral maxilla is the most common site * Locally invasive * Very good prognosis histopathology- * Three main components: - proliferative mesenchymal cells embedded in a collagenous stroma reminiscent of periodontal/gingival ligament, - cemento-osseous matrix, - odontogenic epithelium

Question 267

CANINE ACANTHOMATOUS AMELOBLASTOMA (CAA)

Answer 267

* The most common odontogenic neoplasm in dogs * Mean age: 8.8 years * Rostral mandible is the most common site * Local invasion of underlying bone * Does not metastasise histopathology- Cardinal histologic features of odontogenic epithelium: - palisading of the basilar epithelium, - palisading epithelial cells have antibasilar nuclei, - palisading epithelial cells have a basilar clear zone within the cytoplasm, - odontogenic islands have central areas reminiscent of stellate reticulum (not present in CAA!) * Can morphologically mimic SCC * No reliable IHC markers for odontogenic epithelium in veterinary medicin

Question 268

Diseases of the oesophagus - inflammatory

Answer 268

Oesophagitis Inflammation of the mucosa Often due to acid reflux Weak sphincter? Hernia – most common Oesophageal mucosal metaplasia- Strat sq to columnar Can be iatrogenic Doxycycline in cats Regurge during GA May result in stricture (narroeing)

Question 269

Diseases of the oesophagus - trauma

Answer 269

Choke

Question 270

Diseases of the oesophagus - anomalous

Answer 270

Persistent right aortic arch Vascular ring anomaly German Shepherd dogs Results in dilated oesophagus cranial to constriction Myasthenia gravis- Another important cause of megaoesophagus Congenital and idiopathic forms Idiopathic due to antibodies against acetylcholine receptor This can be secondary tumours of the thymus Aspiration pneumonia

Question 271

abomasitis

Answer 271

disease of the stomach Abomasitis (abomasal bloat) is a relatively rare ruminant disease characterized by inflammation of abomasum in young calves, lambs, and goat kids. Bacterial- Clostridium septicum Braxy Clostridium sordelli Viral- Rarely just the abomasum BVD Malignant catarrhal fever Parasitic

Question 272

gastritis

Answer 272

Gastritis is when the lining of your stomach becomes irritated (inflamed) Gastritis as a single entity is rare in veterinary species Inflammatory bowel disease The stomach has a unique microbial flora due to the pH Helicobacter spp are important in humans and ferrets (H. mustelae) Associated with ulceration Low numbers are consider unremarkable on gastric biopsies from dogs and cats

Question 273

stomach ulcers

Answer 273

Primarily an issue in horses and pigs Complicated and unclear pathogenesis- Inappropriate feed Stress NSAIDs Pigs- Non-glandular oesophageal portion Ruminal ulcers in cows typically associated with ruminal acidosis Caudal vena cava syndrome Fungal overgrowth Abomasal ulceration cause unclear

Question 274

Traumatic reticuloperitonitis

Answer 274

Hardware disease Wire or similar penetrates wall of reticulum Pathophysiology varies from localised transmural inflammation of the wall of the reticulum to peritonitis to pericarditis Clinical signs initially include- ruminoreticular atony moderate ruminal tympany, decrease in milk production pyrexia abdominal pain - arched back, erect hairs at the withers, anxious expression, reluctance to move, and an uneasy, careful gait pain going down hill pole test Chronically ill to sudden death from heart failure

Question 275

Uraemic gastropathy

Answer 275

Diseases of the stomach – metabolic In renal failure, nitrogenous toxins build up in the blood Ulceration and mineralisation

Question 276

Diseases of the stomach – neoplastic

Answer 276

Stomach tumours are generally rare in veterinary species Squamous cell carcinoma in horses -> Adenocarcinoma -> Leiomyoma/sarcoma Gastrointestinal stromal tumours Lymphoma Carcinoids

Question 277

abomasal displacement

Answer 277

Left or right displaced abomasum High yielding dairy cows Multifactorial- Hypomotility Hypocalcaemia High concentrate diet RDA more commonly seen within 1 month of calving LDA more common than RDA Metabolic alkalosis with hypochloremia and hypokalemia

Question 278

bloat

Answer 278

Bloat is a clinical syndrome relating to the clinically appreciable distension of the abdomen due to distension of the abdomen Typically due to the inability of liquid or gas to exit the stomach In cows referred to as ruminal tympany In the cow there are two forms- Frothy (primary) Gas (secondary) Frothy- Typically due to consumption of legumes Lower ruminal ph (normal is 6.5 to 7.5) Blocks eructation Acute and deadly Gas- Due to physical or physiological inability to eructate Choke Vagal indigestion More chronic Difficult to detect post mortem- Bloat line in dogs- Gastric dilation and gastric dilation/dilatation and volvulus (GDV) Gastric dilation/distension can occur if gorge on kibble GDV is typically gaseous with some liquid and food Pathogenesis incompletely understood Volvulus occurs first? The pylorus and duodenum first migrate ventrally and cranially. A volvulus of >180° causes occlusion of the distal oesophagus. Compress vasculature Caudal vena cava Stomach and splenic -> necrosis Fluid “lost” into the stomach Metabolic acidosis Hypovolaemia shock Severely ill, clinical emergency DIC

Question 279

gastric dilation in horses

Answer 279

Gastric dilation as a primary disease rare in horses Will quickly fill with fluid in cases of obstructive colic Also will occur in motility disorders Most well known would be grass sickness Clostridium botulinum Autonomic neurones lost No peristalsis

Question 280

Diseases of the stomach – perforation

Answer 280

Gaseous distension of the GIT is a common post mortem finding, especially farm animals May perforate if left long enough Did this perforation occur before or after death? INFLAMMATION CANNOT OCCUR AFTER DEATH Gross- Fibrin Histo- No cellular response

Question 281

Volvulus

Answer 281

twisting of the gut on mesenteric axis

Question 282

Torsion

Answer 282

twisting of the gut on long axis

Question 283

Intussusception

Answer 283

Intussusception (in-tuh-suh-SEP-shun) is a serious condition in which part of the intestine slides into an adjacent part of the intestine. This telescoping action often blocks food or fluid from passing through. Intussusception also cuts off the blood supply to the part of the intestine that's affected

Question 284

Volvulus, Torsion, and Intussusception can cause

Answer 284

* Thin walled veins get compressed * Venous congestion * Ischaemic infarction * Necrosis * lowered Gut barrier function (bacterial translocation/endotoxaemia) * Obstruction proximal * Perforation * Acute fibrinous/suppurative peritonitis

Question 285

Pathogenesis of diarrhoea

Answer 285

1 Altered structure / permeability (malabsorption) 2 Altered epithelial cell transport (secretory diarrhoea) 3 Osmotic effects (e.g. maldigestion) 4 Altered motility Loss of water Dehydration Haemoconcentration Hypovolaemic shock Loss of ions (principally sodium, potassium and bicarbonate) Metabolic acidosis Hypokalaemia

Question 286

Protein-losing enteropath

Answer 286

(i) Increased permeability to plasma proteins - lost to intestinal lumen (ii) Chronic inflammation - lymphatic blockage Main protein lost is albumin. Loss exceeds liver synthesis ➔hypoalbuminaemia ➔plasma osmotic pressure➔oedema and ascites (wasting + emaciation may also be present

Question 287

Oedema disease of pigs

Answer 287

Enterotoxaemic colibacillosis E. coli F18 Pathogenesis: Associated with dietary changes at weaning Bacterial overgrowth in small intestine Produce verotoxin (Shiga-like) Necrosis of enterocytes and endothelial cells Leakage from vessels results in oedema, which in the brain results in swelling and neurological signs Classical gross post mortem presentation is marked oedema of the spiral colon

Question 288

Swine dysentery

Answer 288

Necrohaemorrhagic enterocolitis Brachyspira hyodysenteriae

Question 289

Salmonellosis

Answer 289

Infectious colitis All salmonella species are enteroinvasive Zoonotic and reportable enterica species serovar Typhimurium Second most important cause of food poisoning in humans Pathogenicity factors include ability to neutralise NO in phagocyte Are phagocytosed but able to survive within phagolysosome Pathophysiology- Septicaemia- Fibrinoid necrosis of vessels and DIC Hepatitis and pneumonia S. choleraesuis Acute enteric - Necrotising ileotyphlocolitis S. typhimurium Chronic enteric- Button ulcers – ddx classical swine fever S. typhimurium Rectal strictures

Question 290

Trichuris

Answer 290

Whipworm Carnivores, ruminants, pigs people Direct life cycle Clinical signs Transient, recurring large bowel diarrhoea with or without blood Rarely, severe infestations result in pseudo-Addison’s

Question 291

Histiocytic ulcerative colitis

Answer 291

Histiocytic ulcerative colitis Boxer dogs and their kin E. coli Histiocytes - granulomatous

Question 292

Anal furunculosis

Answer 292

GSDs Immune-mediated Peri-anal fistulation A fistula is an opening between areas of the body that are not usually connected. In this case between the anus and skin Furunculosis is generally a term used to imply a deep infection of the dermis, typically with ruptured hair follicles and free hair shafts which themselves add to the immune reaction

Question 293

Epithelial tumours of the intestine

Answer 293

tend to be upper GIT In the cat, more commonly lower GIT Papilloma and polyp Adenoma Carcinoma

Question 294

Anal and peri-anal glands

Answer 294

Near the anus there are the anal sac glands and the perianal/circumanal (hepatoid glands) Anal sac glands Apocrine Perianal glands Sebaceous

Question 295

vascular pathology of the liver

Answer 295

Due to the unique blood supply, type of endothelia and architecture of the liver, oedema does not occur Congestion however is very common Infarction is very rare in the liver and tends to occur at the tips Centrilobular (zone 3) hepatocytes are the furthest away from oxygenated blood and are also metabolically the most active, therefore are sensitive to cardiogenic failure Chronic passive congestion due to chronic heart failure will result in chronic low oxygen delivery to the centrilobular hepatocytes Grossly this appears as a zonal pattern with congestion of the central veins and pallor of the centrilobular hepatocytes The centrilobular hepatocytes are pale due to hydropic degeneration (cell swelling – reversible) Chronically these centrilobular hepatocytes may undergo necrosis and may be replaced by fibrosis which grossly appears as a “nutmeg” liver Chronic anaemia will also cause loss of centrilobular hepatocytes Liver lobe torsion is generally rare in veterinary medicine, except in rabbits Telangiectasia is benign distension of sinusoids by blood seen most frequently in the cow. Blood flow may also be compromised secondarily to diaphragmatic hernias Portosystemic shunts Blood from the portal system bypasses the liver Due to anomalous vessel(s) Can be congenital (Yorkshire Terrier) or acquired (Spaniels due to chronic liver disease) Extra-hepatic (small breed) or intra-hepatic (large breed) Clinically Stunted growth Hepatic encephalopathy Biochemistry: Elevated serum bile acids, hypoalbuminemia, hyperammonaemia, hypoglobulinaemia, hypoglycaemia, decreased BUN, hypocholesterolemia Urinalysis: Ammonium biurate crystals in alkaline urine Haematology: mild to moderate microcytic, normochromic, nonregenerative anaemia Grossly the liver is atrophic as lacking growth stimuli

Question 296

viral pathologies of the liver

Answer 296

The liver can be exposed to infectious agents through three main routes Haematogenous Biliary (ascending) Direct extension Neonates also have a direct connection between umbilicus and liver The liver receives 100% of the blood flow from the GIT Defence Kupffer cells Resident macrophages IgA secreted into bile Multifocal random necrosis Herpes Typically affects foetus and neonates Characteristic intranuclear viral inclusion bodies Adenoviruses Canine infectious hepatitis Chickens

Question 297

bacterial pathologies of the iver

Answer 297

Innumerable types of bacteria may infect the liver Bacteria from the GIT May initially be peri-portal Tyzzer’s disease Clostridium pilliforme Foals and laboratory species (gerbils) Abscessation common Ruminal acidosis damages the rumen mucosa, resulting in translocation of Fusobacterium necrophorum into the portal circulation-> hepatic abcesses -> caudal vena cava syndrome Haematogenous bacteria Typically random necrosis Salmonella, Listeria, Clostridia, Yersinia Mycobacteria – pyogranulomas, Ziehl-Neelsen Leptospirosis Campylobacter (aborted lambs) Clinical signs associated with leptospirosis vary and depend on the serovar and the host. See Adewole’s lecture In maintenance hosts, leptospirosis generally is characterized by a low serological response, relatively mild acute clinical signs, and a prolonged renal carrier state which may be associated with chronic renal disease. In incidental hosts, leptospirosis can cause severe disease. Dogs Young > old Serovars icterohemmorrhagiae and canicola were believed to be responsible for most clinical cases of canine leptospirosis and after a bivalent serovar-specific vaccine against canicola and icterohemmorrhagiae came into widespread use, the incidence of "classic" leptospirosis in dogs decreased. Clinical signs: fever, inappetence, vomiting, abdominal pain, diarrhoea, PUPD. Depending on strain and host response, pathogenesis can be primarily due to hepatic or renal dysfunction or a combination. Whilst the renal consequences of lepto were covered in a previous lecture, the liver is another major organ damaged during leptospirosis. The degree of icterus in canine disease usually corresponds to the severity of hepatic necrosis. Cattle The icterus and haemoglobinuria that develop in cattle with leptospirosis results from a specific haemolytic toxin produced by serovar pomona.

Question 298

Chronic canine hepatitis

Answer 298

pathogenesis Spaniels, Dobermans and Labradors all over-represented, therefore genetic factors implicated May be secondary to chronic infection, such as lepto, or copper toxicosis (see later) Clinically the animal will have raised liver enzymes Grossly characterized by a small liver with nodules of hepatocyte regeneration and hyperplasia, separated by bands of fibrosis Proxy for cirrhosis Histopathology reveals periportal inflammation predominantly with portal areas bridged by fibrosis

Question 299

Feline triaditis

Answer 299

In dogs, the common bile duct joins the duodenum at the major duodenal papilla, separately from the pancreatic duct. An accessory pancreatic duct joins the duodenum at the minor papilla in most dogs though anatomic variation exists. In cats, the common bile duct fuses with the pancreatic duct before entering the major papilla. Only 20% of cats are estimated to have an accessory pancreatic duct The canine CBD is 3mm in diameter and the feline CBD is 4mm in diameter Probably due to their unique anatomical features of cats, whenever the intestine is inflamed, so too will be the pancreas and/or biliary tree Cats are typically impressively jaundice Likely post-hepatic Histopath reveals portal and peri-portal inflammation, indicative of ascending infection

Question 300

Infectious - helminths of the liver

Answer 300

The liver can be affected by helminths in two ways Target organ Trematodes Cestodes Visceral migrans Nematodes

Question 301

Fascioloides hepatica

Answer 301

Common liver fluke of ruminants Indirect life cycle Three syndromes Acute fasciolosis, normally seen in sheep, is caused by large numbers of juvenile fluke migrating through the liver. These cause extensive haemorrhage and damage to the liver parenchyma. Animals are typically weak, and anaemic, often with palpably large livers, abdominal pain, ascites and sudden death is common. Chronic fasciolosis occurs in both sheep and cattle and occurs several months after moderate intake of infective cysts. Chronic disease is associated with adult fluke in the bile ducts. Anaemia, loss of appetite and gradual weight loss are common clinical signs. Infection also has an impact on fertility, growth rates and milk production. Black disease (Clostridium novyi) in sheep and bacillary hemoglobinuria (C. hemolyticum) in cattle (and sheep). Migration of immature flukes through the hepatic parenchyma may result in the generation of necessary ischemic conditions for the proliferation of clostridial spores, already within the liver, to proliferate. Once activated the clostridial bacteria produce toxins, resulting in necrosis in the liver and death in sheep with black disease or intravascular haemolysis with associated anaemia and haemoglobinuria in cattle

Question 302

toxic pathology of the liver

Answer 302

Because of its function and exposure to portal blood flow, the liver is a major organ affected by toxins. Centrilobular hepatocytes are most commonly affected, as most toxins are not truly toxic until metabolised by cytochrome P450. Few toxins are toxic without metabolism and will thus cause periportal necrosis. An inexhaustive list of hepatotoxins include Plants and similar Blue-green algae Ragwort (pyrrollizidine alkaloids) Amanita mushrooms Mycotoxins Chemical/drug Xylitol Carprofen Acetaminophen/paracetamol Copper Whilst copper is an essential cofactor of many cellular processes, it is also a toxicant at high enough levels resulting in free radical formation Acute death primarily in ruminants due to haemolytic crisis and acute liver necrosis sheep fed cattle feed and/or deficient in molybdenum Gross – icterus, multifocal pan-lobular hepatic necrosis and gunmetal blue kidneys Chronic Bedlington Terriers have a defect in a copper transport gene, may be other breeds too All dogs with CCH should have copper levels tested Copper levels in dog food too high?

Question 303

metabolic pathology of the liver

Answer 303

Fatty liver disease/ketosis/twin lamb disease/hepatic lipidosis/steatosis Terms used for lipid deposition in the liver Physiology of lipid metabolism - recap Lipid is delivered to the hepatocyte from dietary sources or body fat stores in the form of free fatty acids (FFAs). A small amount of FFAs are also synthesized in the hepatocyte itself from acetate. Some of the FFAs are utilized for the synthesis of cholesterol and phospholipids, and some may be oxidized to ketone bodies (1). Most of the intracellular FFAs are esterified to triglycerides (2). Once triglycerides are produced, they must be complexed to a lipid acceptor protein (or apoprotein) prior to export from the cell (3) as lipoproteins. This requires protein and energy Triglycerides may accumulate if the balance between the synthesis of triglycerides and their utilization or mobilization is deranged. When intracellular triglycerides accumulate, a fatty liver results. Whilst hypoxia and toxins such as aflatoxins that affect protein synthesis in the liver can cause this, one of the main times to see this is when an animal can no longer rely on glucose as an energy source and free fatty acids are thus mobilised from adipose tissue as an alternative energy source This is an example of reversible injury

Question 304

idiopathic pathology of the liver

Answer 304

Gall bladder mucocele Border Terriers

Question 305

neaoplastic pathology of the liver

Answer 305

The liver comprises predominantly Hepatocytes Bile ducts Hepatocellular adenoma/carcinoma Cholangiocellularcarcinoma

Question 306

Lactate

Answer 306

Produced during times of tissue hypoperfusion Serial monitoring rather than single value for porgnosis ↑ shock, low cardiac output, acute liver failure, sepsis, seizures Mammals- Ranges not well defined – rabbits may have higher lactate values than other mammals Reptiles- Is a marker of anaerobic metabolism, can be used to assess physiological stress Birds- Capture myopathy

Question 307

Avian Biochemistry

Answer 307

Rarely provide definitive diagnosis Significant variation with species, age, gender, lifestage Liver and Muscle- AST & Bile Acids most sensitive indicators of liver disease AST not liver specific – can be elevated with muscle damage, inflammation, sepsis GLDH most specific marker oof hepatocellular damage Bile acids reliable indicator of liver function (must collect serum as heparin affects it) Post prandial bile acid elevation so fasted samples preferredCK elevation with muscle damage so should be used alongside AST and GLDH to differentiate ALT, ALP & GGT very non specific Bilirubin concentrations inconsistent in liver disease and across species Biliverdin primary bile pigment Renal Uric acid most reliable test of renal disease (NB affected by many factors) Dehydration and renal disease can both elevate uric acid Can be used as prognostic indicator for gout (>600uml can lead to precipitation in joints) Urea and creatinine not useful for renal disease Creatinine not synthesised by birds (Creatine instead) Urea can be useful for assessing hydration status (but 10-15 x increase not uncommon) Other Protein levels lower in birds c/f mammals Glucose levels more stable in birds as not utilised by RBCs but see stress and postprandial↑ BG ranges in birds higher than mamamls Calcium – consider total and ionised calcium Egg laying biochemistry- See huge elevation in Calcium to produce egg shell This is predominantly Bound and not metabolically active

Question 308

Reptilian Biochemistry

Answer 308

Lymph dilution common and will reduce all biochemical values Effects of sex, season profound Liver and muscle ALT, ALP, LDH non specific AST found in liver, kidneys & muscle so should be assessed alongside CK and LDH GGT in liver and kidneys; sensitive for hepatic & renal disease GDH may be useful indicator of hepatocellular necrosis Biliverdin is primary bile pigment – no assay commercially available Bile acids vary across reptilian taxa Renal Uric acid main excretory product of protein metabolism – produced in the liver (gout) Fasted samples required in carnivorous reptiles Renal Uric acid main excretory product of protein metabolism – produced in the liver Fasted samples required in carnivorous reptiles – postprandial elevations Uric acid marker of renal disease, dehydration Persistent elevations can --> visceral & articular gout Reduced uric acid levels seen in hepatic disease Urea and creatinine less useful as low and variable levels May see elevated urea levels in early rehydration as can be resorbed across bladder wall Ca:P ratio one of most useful indicators of renal disease Sodium ↑ with dietary intake and dehydration and ↓ with renal disease, GI losses Other Calcium – egg laying females

Question 309

Exotic Mammal Biochemistry

Answer 309

Variations between carnivores & herbivorous species Liver & Muscle ALT elevations seen with hepatocellular damage so can be useful initial screening parameter AST found min muscle and liver so should be interpreted alongside SK ALP non specific for liver, elevated in young, growing animals or high bone turnover Calcium Rabbits unique amongst mammals in their Ca absorption mechanism Dietary intake can cause hypercalcaemia Renal Urea elevations as per other mammals with dehydration, renal disease, obstruction Can see hyper or hypcalcaemia Other- Hepatic lipidosis  elevated trigycerides & cholesterol

Question 309

Exotic Mammal Biochemistry

Answer 309

Variations between carnivores & herbivorous species Liver & Muscle ALT elevations seen with hepatocellular damage so can be useful initial screening parameter AST found min muscle and liver so should be interpreted alongside SK ALP non specific for liver, elevated in young, growing animals or high bone turnover Calcium Rabbits unique amongst mammals in their Ca absorption mechanism Dietary intake can cause hypercalcaemia Renal Urea elevations as per other mammals with dehydration, renal disease, obstruction Can see hyper or hypcalcaemia Other- Hepatic lipidosis  elevated trigycerides & cholesterol

Question 310

ERYTHROCYTOSIS (POLYCYTHAEMIA)

Answer 310

a high concentration of red blood cells in the blood Increased red cell mass, evidenced in increased : Haemoglobin Packed cell volume (PCV) Haematocrit (HCT) Red blood cell count (RBC) Physiological Breed related Reference intervals should be different for Greyhounds vs other dogs Thoroughbreds vs ponies Dehydration (PCV up to 60%) fluid loss with a stable red cell mass Clinical signs may be present Lab test abnormalities serum total proteins Often but not always increased serum sodium urine specific gravity PRIMARY(absolute) Polycythaemia rubra vera Bone marrow neoplastic dz Clonal proliferation and maturation of RBCs WITHOUT normal feedback mechanisms EPO low (in theory!) neurological signs, seizures, paroxysmal sneezing, cardiopulmonary signs, retinal changes (high blood viscosity) High PCV!! (>65%) SECONDARY(absolute) Hypoxia (altitude, heart/pulmonary dz) Bone Marrow responds>EPO>>RBC Solid tumours Renal carcinoma>> EPO>> >>RBC

Question 311

Leukocyte disorders/patterns

Answer 311

Neutrophilia and neutropenia Left shift and toxic change Lymphocytosis and lymphopenia Monocytosis Eosinophilia/Basophila “Stress leukogram”

Question 312

Neutrophilia

Answer 312

Increased production 1. TO MEET DEMAND Infections Immune mediated diseases Inflammation Neoplasia (COMMON) 2.INDEPENDENT OF DEMAND Bone marrow neoplasia = Leukaemia (UNCOMMON) 3. Persistence in circulation Chronic stress Glucocorticoids (steroids) 4. Redistribution (shift from marginating to circulating pool) Excitement (epinephrine) Stress(glucocorticoids) increased blood pressure

Question 313

Neutropenia

Answer 313

a low number of white blood cells called neutrophils in your blood. Increased demand (migration into tissue) Bacterial sepsis, abscess Endotoxaemia, tumour necrosis Redistribution In response to acute endotoxaemia (shift from circulating to marginating pool) Decreased production Bone marrow dz, Drugs Increased destruction Immune mediated

Question 314

Band neutrophils

Answer 314

released with increased demand slightly less mature than segmented neutrophils and have indented, unsegmented "C" or "S" shaped nuclei. Band neutrophils normally account for approximately 5-10% of peripheral blood leukocytes. An increased proportion of band neutrophils can be seen in infectious and inflammatory conditions. Usually “U” shaped or “S” shaped nucleus with parallel sides ie minimal indentation/ segmentation

Question 315

Toxic neutrophils

Answer 315

Maturation defects Seen with increased demand Not necessarily sepsis, can happen with sterile demand Pyothorax, pancreatitis, pyometra etc. under conditions that intensely stimulate neutrophil production and shorten the maturation time in marrow.

Question 316

Signs of toxicity

Answer 316

Dohle bodies Foamy cytoplasm Bluish cytoplasm Toxic granules - rare Peripheral blood: Toxic verses non-toxic neutrophils Tissues/fluids: Degenerate verses non-degenerate neutrophils

Question 317

Dohle bodies

Answer 317

Döhle bodies are single or multiple blue cytoplasmic inclusions that are remnants of rough endoplasmic reticulum. They are associated with myeloid left shifts and are seen in conjunction with toxic granulation. he presence of Döhle bodies, nuclear immaturity, "toxic" cytoplasmic granulation, and giant platelets may indicate, at least in some measure, a general metabolic disturbance of the hematopoietic system.

Question 318

Foamy cytoplasm

Answer 318

have a bubbly (foamy) cytoplasm. Most are macrophages (1.76) that have phagocytized lipid material, but some are cells of another derivation that have a similar multivacuolated cytoplasm. Compare with clear cells Foam cells form through dysregulated lipid metabolism in mammalian macrophages: lipid accumulation that exceeds the homeostatic capacity of macrophages triggers lipid droplet formation

Question 319

Toxic granules

Answer 319

rare he term used to describe an increase in staining density and possibly number of granules that occurs regularly with bacterial infection and often with other causes of inflammation Toxic granulation is seen in cases of severe infection, as a result of denatured proteins in rheumatoid arthritis or, less frequently, as a result of autophagocytosis. Infection is the most frequent cause of toxic granulatio

Question 320

LYMPHOCYTOSIS

Answer 320

1. Increased production in response to increased demand Persistent antigenic stimulation (fungal, protozoal, viral), Post vaccination, young animals 2. Increased production without demand Lymphoid Leukaemia, Lymphoma 3. Redistribution Excitement/acute stress (epinephrine response) (physiological; as for neutrophils) inhibition of recirculation, release from the thoracic duct Hypoadrenocorticism (10-20% of cases)

Question 321

LYMPHOPENIA

Answer 321

Loss of lymphocytes Loss of chylous fluid (rich in lymphocytes) Protein losing enteropathy, chylothorax Decreased production Viral infections, lympholytic drugs (for chemotherapy) Redistribution Chronic stress, Glucocorticoids (steroids) Trapped in lymph nodes move from circulation into bone marrow and tissues lymphocytolysis

Question 322

MONOCYTOSIS

Answer 322

1. Increased production by the bone marrow to meet demand Infections, immune-mediated dz, inflammation, necrosis, sepsis, neoplasia 2. Increased production by the bone marrow without demand Leukaemia (myelomonocytic) 3. Redistribution Chronic stress, Glucocorticoids (steroids) Move monocytes from the marginating to the circulating pool

Question 323

EOSINOPHILIA

Answer 323

1. Increased production in response to increased demand Parasitic infection, allergic disease”, inflammation of mast cell rich tissue (intestines, skin, lungs, uterus) 2. Increased production without demand Neoplasia (lymphoma, mast cell tumour, squamous cell carcinoma) Hypereosinophilic syndrome Peripheral eosinophilia & infiltration of organs with eosinophils without obvious cause Eosinophilic Leukaemia (rare) 3. Hypoadrenocorticism (lack of glucocorticoids)

Question 324

BASOPHILIA

Answer 324

. Increased numbers due to increased demand Hypersensitivities drugs, food, insect bites/stings Parasitism especially Dirofiliaria, but also GI parasites, fleas and ticks Inflammation 2. Increased numbers without demand Paraneoplastic (particularly with mast cell tumours) Basophilic leukaemia (rare)

Question 325

“Stress leukogram”

Answer 325

Leukocyte pattern due to the effect of increased cortisol Classically neutrophilia +/-monocytosis with lymphopenia and eosinopenia Most commonly seen dogs and cats May be absent when expected eg Addison’s disease

Question 326

Important species differences in Red cell morphology Regenerative response Eosinophil morphology and Leukocyte responses

Answer 326

red cells- Dogs – have most obvious central pallor Alpacas – oval shaped but no nucleus Birds/reptiles - nucleated red cells regenerative resonse- Regeneration in most species noted by increased polychromatic red cells (reticulocytes) in circulation Horses do not release polychromatic red cells into circulation so cannot assess regeneration this way eukocyte response- Cat leukocyte response to epinephrine more "extreme" than other species Classic  complete"stress" glucocorticoid response most commonly seen in dogs Dogs typically display neutrophilia with inflammation (unless severe), cattle more commonly neutropenia, cats and horses somewhere in between.

Question 327

Complete Blood Count (CBC)

Answer 327

EDTA BLOOD SAMPLE Measured Red Cell Parameters: Haemoglobin (Hb) (uses a biochemical method) Red blood cell concentration (RBC/ul) Mean cell volume (MCV); average size of RBCs Calculated Red cell parameters: Haematocrit (HCT)  calculated from those measured (HCT = MCV x RBC)  Equivalent of manual PCV Mean corpuscular haemoglobin (MCH) calculated (MCH = Hb x10 / RBC) Mean corpuscular haemoglobin concentration (MCHC) MCHC=Hb/HCT Some analysers: Red cell distribution width (RDW) – indication of variation in red cell size Reticulocyte counts/percentage – measure of regeneration Reticulocyte Hb – potential marker for iron deficiency Plateletcrit (PCT) – equivalent of HCT for platelets

Question 328

Packed cell volume

Answer 328

PCV – percentage of red cells in a volume of blood. Manual technique. Centrifuged whole blood, red cells read as a % of column. Buffy coat assessment Plasma – clear/ straw or pink if haemolysed Total proteins measurement

Question 329

Regenerative anemia

Answer 329

Anisocytosis- red blood cells (RBCs) that are unequal in size Polychromatophils- efers to how blood cells look under a microscope when the cells are stained with special dyes. It means there is more staining than normal with certain dyes. The extra staining is due to an increased number of immature red blood cells (RBCs) called reticulocytes Reticulocytes- red blood cells that are still developing Nucleated RBC- the body is so desperate for red blood cells that it has begun producing them outside of the bone marrow. Howell-Jolly bodies-nuclear remnants that are found in the RBCs

Question 330

Reticulocytes and Polychromatophils

Answer 330

On a Diff – Quik or Giemsa stained smear, young red cells containing reticulin show up as larger, bluer cells: polychromatophils Stain the same cells with New Methylene Blue, and you can see the reticulin : the cells are then called reticulocytes THEY ARE THE SAME CELLS

Question 331

Spherocytes

Answer 331

Spherocytes are often difficult to recognize – MUST LOOK FOR THEM IN THE MONOLAYER They are smaller, darker and have no central pallor Can be extremely difficult/impossible to see in species other than dogs

Question 332

Heinz bodies

Answer 332

ggregates of denatured, precipitated hemoglobin within erythrocytes that form as hemoglobin with oxidative damage is metabolized. look like blebs on outside of cell sign of oxidative injury. Haemoglobin is oxidised and pushed to cell margin, no longer functional Paracetamol in cats, onions, some toxins (eg Zinc), diabetic ketoacidosis are some common causes of Heinz bodies/eccentrocytes

Question 333

eccentrocytes

Answer 333

appear in a peripheral blood smear to have their hemoglobin shifted to one side of the cell. This abnormality, which is confined to the RBC membrane and cytoskeleton, is induced by oxidative damage. sign of oxidative injury. Haemoglobin is oxidised and pushed to cell margin, no longer functional Paracetamol in cats, onions, some toxins (eg Zinc), diabetic ketoacidosis are some common causes of Heinz bodies/eccentrocytes

Question 334

Acanthocytes

Answer 334

look like splats- long fingers come off cell body

Question 335

Schistocytes

Answer 335

Red cell fragments forming secondary to being squeezed through abnormal blood vessels (eg haemangiosarcoma) or being fragile (eg iron deficiency)

Question 336

PCR (EDTA sample) tests are available for:

Answer 336

the haemotropic Mycoplasmas in cats Babesia species in dogs Ehrlichia and Anaplasma in dogs FIV/FeLV

Question 337

Serology (serum sample) is available for:

Answer 337

Leptospirosis Panleukopaenia, canine parvovirus equine infectious anaemia Feline coronavirus

Question 338

Slide agglutination test

Answer 338

To try and distinguish rouleux and true agglutination The sample is examined microscopically after the addition of saline. Rouleaux formations disperse, but agglutination persists.

Question 339

Coomb’s test

Answer 339

Coomb’s reagent (containing antibodies to IgG, Igm and C3) in dilutions is reacted with washed patient red cells to detect those cells opsonised with antibody and complement Opsonised cells binding antibody agglutinate Agglutinated red cells fail to settle in round bottom wells Significantly positive result provides support for immune mediated component to anemia

Question 340

Faecal occult blood

Answer 340

Up to 50% blood volume may be lost into the GI tract before it is grossly visible in the faeces. These tests generally detect peroxidase activity (present in haemoglobin) and may be 50x more sensitive than visual examination. They are prone to false positives due to meat diets, vitamin C and some vegetables (eg brassicas, cantaloupe melon (true, it’s on Wikipedia!!)). It is advisable to feed restricted diets for at least 3d prior to the test. Which diets? Traditionally white meat has been used Rice / cottage cheese may be better Commercial dry diets. Variable but if heat treated may be OK. Can always send in sample of dry commercial food at same time as faeces.

Question 341

ANAEMIA

Answer 341

Reduction in red cell mass, evidenced in decreased: Haemoglobin Provides information on the total O2 carrying capacity Packed cell volume (PCV) Haematocrit (HCT) Red blood cell count (RBC) The effects of anaemia are due to reduced oxygenation of tissues. Tissue hypoxia activates the following 4 main compensatory mechanisms, which serve to maintain tissue oxygen levels as near to normal as possible. Increased oxygen delivery: The affinity of Hb for O2 is reduced so a higher proportion of O2, which is carried by the Hb, is available to be released to the tissues.  Increased cardiac output: Serves to increase tissue oxygenation Increased RBC production: Tissue hypoxia causes the release of the hormone erythropoietin from the kidneys.  Vasoconstriction: Shunting of blood away from tissues with low O2 demand (i.e. skin) to tissues with high O2 n demand (i.e. brain). Mucous membrane pallor Lethargy Exercise intolerance Tachycardia Tachypnoea Collapse Icterus Melaena Pica

Question 342

Haemolysis

Answer 342

Extravascular More common Macrophages Spleen and liver ± Icterus (jaundice) Intravascular Acute, severe Haemoglobinaemia Haemoglobinuria Ghost cells +/- icterus

Question 343

Haemolytic anaemia

Answer 343

Immune-mediated (common – primary verses secondary) Infections (less common) Babesia Mycoplasma Inherited RBC metabolic defects (rare) Toxins Severe Hypophosphataemia (rare) 1. IMHA One of the most common causes of anaemia in dogs One of the most common immune-mediated Dz Primary IMHA (AIHA) Most common Idiopathic Breed predispositions Young-middle aged Female>male Pale mucous membranes +/- tachycardia, bounding pulses, systolic murmur ± Tachypnoea Jaundice Hepatosplenomegaly Pyrexia, mild lymphadenopathy Thromboembolic disease Secondary IMHA Infections Neoplasia Drugs No single pathognomonic test HAEMATOLOGY Anaemia (usually regenerative) plus any of: Agglutination(A) Spherocytosis (S) Positive Coombs’ test Test detects the presence of antibodies on the RBC

Question 344

. Haemolytic anaemia

Answer 344

Secondary to Infection Parasites Haemoplasmas in cats Babesia in dogs/cattle Bacteria Leptospira Clostridium

Question 345

. Inherited RBC metabolic defects

Answer 345

These are RARE PFK deficiency (Springers) PK deficiency (Basenjis, Somalis, Abysinnians) Genetic tests (PCR) available for diagnosis

Question 346

Basophilic stippling

Answer 346

the presence of numerous basophilic granules that are dispersed through the cytoplasm basophilic stippling is a frequent manifestation of hematologic disease in the peripheral blood, and it is also observable in bone marrow aspirates. It is implicated in cases of lead poisoning but can be an indicator of various heavy metal toxicities

Question 347

Stain precipitate

Answer 347

Stain precipitate mimics bacteria, including cocci and Mycoplasma species. Generally, the stain precipitate is purple, whereas bacteria are blue (with a Wright's stain). usually results from the use of aged staining solutions and/or inadequate rinsing of slides following application of stain.

Question 348

B. divergens apearence on Fresh blood smears

Answer 348

Single or paired round oval or pear shaped structures Low sensitivity pcr better- edta

Question 349

Anaplasma phagocytophilium apperence on Blood smear

Answer 349

Mulberry like micro-colonies (morulae) of coccobacciliary bacteria Size 0.2-05 um diameter Within cytoplasmic bound vacuoles PCR (pan-Piroplasmosis PCR for Babesia and Anaplasma, APHA) Serology (IFA, ELISA) (not routinely used )

Question 350

Equine Piroplasmosis appearence on blood smear

Answer 350

B. caballi - Single or paired pear shaped meet at posterior end in erythrocytes T. equi - Smaller Round or ovoid Tetra shapes ‘maltese cross’ in erythrocytes

Question 351

Mycoplasma haemolamae appearene on blood smear

Answer 351

RBC small and elliptoid Lots of small blue dots on surface of RBC Identify on blood smear (make fresh as organisms will fall off)

Question 352

mammal red blood cells

Answer 352

Anucleated (No nucleus) Anisocytosis/Polychromasia common in some species Shorter half life c/f dogs and cats

Question 353

Red Blood Cell Appearance - Birds

Answer 353

Erythrocytes Nucleated Larger than mammals’ smaller than reptiles’ Elliptical cells Elliptical, central nucleus

Question 354

Red Blood Cell Appearance - Reptiles

Answer 354

Erythrocytes Nucleated Larger cells than birds and mammals Blunt ended ellipse Central round/ovoid nucleus with Irregular margin

Question 355

Non regenerative anaemia - reptiles

Answer 355

Most common form of anaemia in reptiles Systemic disease Starvation Chronic disease GI disease Neoplasia Suboptimal Husbandry

Question 356

Non regenerative anaemia - Birds

Answer 356

Systemic disease Starvation Chronic disease Neoplasia Drugs Suboptimal Husbandry Many infectious diseases Aspergillosis, Chlamydiosis, TB, circovirus, chronic bacterial infection

Question 357

Heterophils

Answer 357

in birds and reptiles Stain differently but comparable function to neutrophils heterophils have diffrent shaped nucleus and granules Most mammals have neutrophils Rabbits and some rodents – heterophils Reptiles, Birds – heterophils Most common leukocyte to vary in disease Predominant leukocyte usually Some species lymphocytic Rabbits, G. Pigs, mice, rats, gerbils Heterophil:lymphocyte ratio Phagocytosis and lysosomal action Irregularly round cell Granules Often rod shaped granules esp in birds Granules often fused together Basophilic nucleus Lobed - 2-3 lobes in birds Non lobed oval nucleus in reptiles Very variable appearance in reptiles Heterophilia/Neutrophilia Stress (transport, restraint, fear, crowding, management, trauma, temperature stress, anaesthesia) Infectious causes , inflammation Neoplasia Necrosis Differentiate between physiological and pathological heterophilia Left shift (increased band heterophils) Less lobed nucleus More basophilic (bluer), fewer granules Toxic Changes (main marker in reptiles) NB reptiles huge variation Biochemistry changes (Fibrinogen assays, A:G ratios, acute     phase proteins Pseudoheteropaenia True Hetero/Neutropaenia Sepsis Viral infections Myelosuppression Iatrogenic/drugs Neoplasia) Combined with left shift in severe consumption in overwhelming infection NB in Lymphocytic species, heterophil:ymphocyte ratio more reliable

Question 358

eosinophils in exotics

Answer 358

Exact function unknown in some species Loosely foreign antigen Larger than heterophils with round outline Red/orange round cytoplasmic granules Some species have pale blue granules eg AGP/iguanas Birds – bilobed nucleus Reptiles – elongated/round nucleus Generally in fewer numbers Raptors higher eosinophils <15% Reptiles variable Eosinopaenia Typically low numbers so eosinopaenia hard to identify/define Stress Glucocorticoids Eosinophilia Less clearly defined than in dogs/cats where usually parasites Artefactual Foreign Antigen Marked tissue trauma Parasites Rarely hypersensitivity

Question 359

basophils in exotics

Answer 359

Round to oval nucleus, lobed in mammals Frequent round purple cytoplasmic granules Nucleus may be obscured by granules Some species variation in appearance of granules/pattern Higher numbers c/f eosinophils Rabbits 5% (but can be <30%) Birds <6% Reptiles can have very high numbers Eg. Up to 40% in aquatic turtles normal Differentiate from mast cells (rare)

Question 360

Lymphocytes in exotics

Answer 360

Similar function in all exotics species Immunologic function T lymphocytes - cell mediated immunity B lymphocytes - humoral immunity Scant weakly basophilic cytoplasm High nucleus:cytoplasm ratio No granules Round, central or slightly eccentric nucleus Easily confused with thrombocytes and monocytes Predominant leukocyte in some species Rodents, rabbits, waterfowl, some snakes and other reptiles Neutro/Heterophil:Lymphocyte ratio often more important than absolute numbers Lymphopaenia Relative lymphopaenia in lymphocytic species with a heterophilia/neutrophilia Severe stress Corticosteroids (endogenous or exogenous) Toxins Acute infection Lymphocytosis Young animals have higher baseline, as do some breeds and species Excitement Lymphoma/Neoplasia

Question 361

Monocytes in exotics

Answer 361

Large cells (generally largest leykocyte in peripheral blood – foten twice the size of RBCS) Irregularly shaped nucleus Lacy chromatin Abundant cytoplasm Reptiles Variable number of fine red cytoplasmic granules In snakes even more prominent granules and referred to as azurophils Elevated in chronic inflammation Granulomatous disease

Question 362

Azurophils

Answer 362

– snakes only Slightly smaller than the monocyte Non segmented nucleus Darker more basophilic cytoplasm than monocyte Prominent red cytoplasmic granules Appearance and function more similar to neutrophils Can be <35% Increase with acute inflammation or bacterial infection (similar to neutrophils) but do also have heterophils No real clinical benefit in differentiating from monocytes

Question 363

Monocytosis/Monocytopenia

Answer 363

Function Monocytosis Acute and Chronic Inflammation Corticosteroid response Viral Infection Granulomatous disease Necrosis Neoplasia Foreign body Suppuration Monocytopenia

Question 364

Thrombocytes in birds and reptiles

Answer 364

Nucleated cells Second most numerous cell in peripheral blood Small, round to oval cells Round to oval nucleus High Nucleus:Cytoplasm ratio May contain eosinophilic granules 1 or 2 in one area of the cytoplasm Clump or form aggregates in blood films Avian thrombocytes capable of phagocytosis

Question 365

Avian Biochemistry

Answer 365

Rarely provide definitive diagnosis Significant variation with species, age, gender, lifestage Liver and Muscle AST & Bile Acids most sensitive indicators of liver disease AST not liver specific – can be elevated with muscle damage, inflammation, sepsis GLDH most specific marker oof hepatocellular damage Bile acids reliable indicator of liver function (must collect serum as heparin affects it) Post prandial bile acid elevation so fasted samples preferredCK elevation with muscle damage so should be used alongside AST and GLDH to differentiate ALT, ALP & GGT very non specific Bilirubin concentrations inconsistent in liver disease and across species Biliverdin primary bile pigment

Question 366

Hypoxic shock

Answer 366

Impaired oxygen delivery to the cells Anaemia Decreased haemoglobin saturation – carbon monoxide Respiratory disease

Question 367

Hypovolaemic shock

Answer 367

Hypovolaemia occurs when fluid is lost primarily from the intravascular compartment - a relatively small total loss of fluid has profound physiological consequences with the development of hypovolaemic shock. In this circumstance, treatment with fluids centers around rapid replacement of the lost volume to restore tissue perfusion. Conversely dehydration represents fluid loss from all three body fluid compartments. It commonly occurs with more gradual fluid losses where there is time for water to move between body fluid compartments. Total body fluid losses may be much larger than with hypovolaemia but as the fluid losses are borne between all the compartments, it has much less profound and immediate physiological effects. Acute blood loss Trauma Severe dehydration Third spacing = Third-spacing occurs when too much fluid moves from the intravascular space (blood vessels) into the interstitial or “third” space—the nonfunctional area between cells. – edema, pleural or peritoneal cavity

Question 368

Bilirubin

Answer 368

end product of haemoglobin metabolism Unconjugated Conjugated Unconjudated bilirubin – direct breakdown product of haem – in soluble and can only travel in blood stream attached to albumin and unable to excrete directly from the body Conjugated is water soluble and can be excreted from the body Uncojudated bilirubin is formed by the breakdown of hemoglobin in the red blood cells. The liver converts this bilirubin into direct bilirubin, which can then be released into the intestine by the gallbladder for elimination. Total bilirubin levels are therefore indicative of both the destruction of red blood cells and the proper functioning of the liver, gallbladder, and bile ducts. This is bound to albumin and is the dominant form of total bilirubin in blood. It is produced in macrophages from breakdown of heme groups (specifically the porphyrin ring of heme). The biggest source of heme is hemoglobin within red blood cells (RBC)  Conjugation renders bilirubin water soluble. Only very small amounts in blood because it is normally excreted into bile.  What will cause Janudice – it is an increase in the pigmentation in the blood stream and tissues Disease processes have to be caused by a breakdown in part of the pathway Total bilirubin levels are therefore indicative of both the destruction of red blood cells and the proper functioning of the liver, gallbladder, and bile ducts

Question 369

pre-hepatic jandice

Answer 369

Accelerated red blood cell destruction and increased bilirubin production Immune mediated haemolytic anaemia (IMHA If this bilirubinemia overwhelms the liver’s functional capacity for uptake, conjugation, and secretion, bilirubin is refluxed from the liver into the circulation resulting in hyperbilirubinemia and icterus.2

Question 370

hepatic jandice

Answer 370

Hepatocellular disease Reduced hepatocyte uptake Reduced Conjugation Reduced secretion of bilirubin intrahepatic cholestasis associated with hepatocellular injury, necrosis, or dysfunction Hyperbilirubinemia that occurs in most diseases of the liver is a mixture of conjugated and unconjugated bilirubin in varying proportions – reflux back into the intravascular system

Question 371

post hepatic jaundice

Answer 371

Disruption of bile flow through the extrahepatic biliary system

Question 372

Megakaryocytes

Answer 372

Reside in the bone marrow Large multinucleated cells with abundant cytoplasm Platelets Sheared off fragments of megakaryocyte cytoplasm Smaller than a RBC Anucleate, irregular, granular

Question 373

pseudo thrombocytopenia

Answer 373

Platelet clumps Clotting during sampling In vivo activation Platelets counted as RBCs (and vice versa) Dogs Akitas: Small red blood cells CKCS: Macroplatelets Cats, Goats Small red blood cells

Question 374

D-Dimers

Answer 374

D-Dimers Measured on citrated plasma Form when cross linked fibrin is cleaved by plasmin Used to assess ↑ fibrinolysis associated with coagulation Clots are dissolved → excessive fibrinolysis = ↑ D-Dimers Causes Localised or disseminated intravascular coagulation (DIC) Sepsis, systemic inflammation, haemorrhage, neoplasia, surgery, immune-mediated disease Decreased hepatic or renal clearance

Question 375

Von Willebrand Disease

Answer 375

Von Willebrand factor (vWF) Exposed when vessel wall is damaged Binds platelets to endothelial wall Von Willebrand Disease Most common hereditary bleeding disease in dogs Doberman most common breed Different types = Reduced concentration or complete absence of vWF

Question 376

APTT and PT

Answer 376

Coagulation times’ = APTT and PT Stimulate the coagulation pathway in vivo The it takes until a clot is detected Activated partial thromboplastin time = APTT Assesses intrinsic + common pathways Prothrombin time = PT Assesses extrinsic + common pathways

Question 377

Differentials for prolonged APTT

Answer 377

Intrinsic + Common factors XII, XI, IX, VIII, X, V, II, I Hereditary Haemophilia A = deficiency in factor VIII Haemophilia B = deficiency in factor IX Factor XII deficiency = most common in cats, no clinical haemorrhage Acquired Hepatic disease Vitamin K malabsorption Vitamin K antagonism (rodenticide toxicity) DIC or local consumption of coagulation factors

Question 378

Differentials for prolonged PT

Answer 378

Extrinsic + Common factors VII, X, V, II, I Hereditary Factor VII - prolonged PT, normal aPTT Affected dogs generally do not have a history of bleeding Bruising / prolonged bleeding following surgery Acquired Hepatic disease Vitamin K malabsorption / antagonism (rodenticide toxicity) DIC or local consumption of coagulation factors

Question 379

Vitamin K Deficiency / Antagonism

Answer 379

Vitamin K dependent factors Factors II, VII, IX & X These factors require Vitamin K to be functional Malabsorption of Vitamin K Gastrointestinal disease (e.g. inflammatory bowel disease) Vitamin K antagonism Rodenticide toxicity (e.g. Warfarin) - dogs Mouldy sweet clover - ruminants, horses, pigs

Question 380

Haemophilia A =

Answer 380

Factor VIII

Question 381

Haemophilia B

Answer 381

= Factor IX Diagnosis <1% factor VIII activity: reference interval: 50-200% Prolonged APTT only (not PT) Dogs & cats Mild in small dogs, severe in large dogs X-linked recessive mutation in Factor VIII gene Males are either affected or not (never carriers) Females can be free of the defect, carriers (heterozygous) or rarely affected (homozygous).

Question 382

cytology

Answer 382

Microscopic examination of tissue samples spread onto slides Histology looks at architecture, cytology has no architecture - look at individual cell morphology Aspirates – solid tissue Needle only Intermittent suction Continuous suction Impression smears - mucosa, ears, biopsies Wash / Lavage – trachea, BAL, nasal, prostate Ultrasound guided – watch out for ultrasound / lubricant gel! No anaesthetic and low risk of complications Relatively quick procedure and less invasive Rapid results – emergency cases, clients waiting, same day intervention Older patient - removal of a benign tumour? Grading of tumours to help with surgical or chemo planning Surgical planning Staging of tumours Fluid classifications – Transudate, Modified Transudate, Exudate Infections (septic abdomen, ear cytology) Ancillary tests PARR analysis and Flow Cytometry PCR for infectious diseases

Question 383

Flaming plasma cell

Answer 383

Flame cells are plasma cells with a distinctive pinkish hue in the outer rim of the cytoplasm. This appearance is thought to be the result of precipitated immunoglobulin. These cells can be found in plasma cell dyscrasias as well as cases of chronic infection or inflammation

Question 384

Reactive lymphoid hyperplasia

Answer 384

a benign nodular lesion, histopathologically characterized by marked proliferation of non-neoplastic, polyclonal lymphocytes forming follicles with an active germinal center -Mott cells -Mixed small, intermediate, large lymphocytes

Question 385

types of inflamation

Answer 385

Inflammation Acute / suppurative - neutrophils Chronic active / pyogranulomatous – neutrophils and macrophages Chronic / granulomatous – macrophages (multinucleated), lymphocytes, plasma cells Specific e.g. eosinophilic Concurrent tissue reaction – hyperplasia / dysplasia Infection Bacteria – rods / cocci / coccobacilli Yeasts and fungi Mycobacterium Protozoa

Question 386

Degenerate neutrophils

Answer 386

Degeneration of neutrophils is indicated by swelling of the nucleus, with the nucleus appearing lighter staining and smudged- kind of like it is swollen. The cells may also lyse. When degenerate neutrophils are seen, you should look carefully for microorganisms – especially bacteria.

Question 387

Hyperplasia

Answer 387

Hyperplasia = increase in the number of cells in a tissue Non-neoplastic enlargement of a tissue. Hyperplasia is often the result of hormonal influences (e.g. benign prostatic hyperplasia, perianal gland hyperplasia), tissue injury (e.g. regenerative nodules in the liver, granulation tissue with fibroplasia) or antigenic stimulation (lymphoid hyperplasia). Aspiration of hyperplastic lesions: Higher than expected cellularity Cells may display some mild criteria of malignancy Mildly increased N:C ratio Darker blue cytoplasm More prominent nucleoli Finer chromatin than normal

Question 388

Dysplasia

Answer 388

Dysplasia = disordered growth Common in epithelial tissue secondary to inflammation or irritation.  Loss of uniformity of the individual cells Disordered architectural arrangement of the cells. Atypical cytologic features: Nuclear to cytoplasmic asynchrony Increased cytoplasmic basophilia Anisokaryosis and anisocytosis. Dysplasia can be cytologically difficult to distinguish from neoplasia as dysplastic lesions often contain more criteria of malignancy than strictly hyperplastic lesions.

Question 389

Neoplasia

Answer 389

Neoplasia = abnormal and excessive growth of tissue. Growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed Hyperplasia, metaplasia, and dysplasia are reversible because they are results of a stimulus.  Neoplasia is irreversible because it is autonomous

Question 390

epithelial neoplasia

Answer 390

Arrangement Monolayer sheets, clusters, rows, palisades and acinar. Cohesive with distinct tight junctions (desmosomes) Clear lines between cells. Shape Columnar, cuboidal or polygonal Nuclei Round to oval. Epithelial cells can look round in fluid or when poorly differentiated. E.G.: Squamous cell carcinoma, adenoma and adenocarcinoma. Benign: Adenomas Malignant: Squamous cell carcinomas

Question 391

Mesenchymal neoplasia

Answer 391

Arrangement Often see individual cells but occasionally seen in aggregates. Loosely arranged with extracellular matrix and individualised spindle or stellate cells. Shape "Spindle cell" - spindle shaped cells, fusiform or stellate. Wispy cytoplasmic borders, the borders are not distinct. Cytoplasm can contain vacuoles Nuclei Round to elliptical (oval). Cytoplasm can contain vacuoles. Samples are often poorly cellular in benign lesions, but can be very cellular in malignancy. Arise from connective tissue e.g.: fibroblasts, osteoblasts, adipocytes, myocytes and vascular lining cells.  E.g Osteosarcoma, Haemangiosarcomas etc. Benign: Fibromas, lipomas Malignant: Sarcomas, soft tissue sarcoma, haemangiosarcoma etc.

Question 392

Lipoma

Answer 392

Greasy slides Large fat filled adipocytes in aggregates Often have capillaries going through them Often benign, can have infiltrative forms Liposarcoma - malignant version

Question 393

Round Cell neoplasia

Answer 393

Arrangement Discrete and individually arranged Shape Round tumour cells Well defined / distinct cytoplasmic borders Nuclei Round to oval large nucleus (can be indented) Exfoliate well 5 main examples: Mast cell tumour Lymphoma / leukaemia Histocytoma / histiocytic sarcoma Plasma cell tumour / plasmacytoma / multiple myeloma Transmissible venereal tumour

Question 394

Mast cell tumour

Answer 394

Round cells Central round nuclei Lots of magenta granules in the cytoplasm Fibroblasts, eosinophils and ribbons of pink matrix

Question 395

Histiocytoma

Answer 395

Rounds cells individually arranged Light blue cytoplasm, Nuclei round to oval to cleaved Often accompanied by lymphocytes and plasma cells Mass in a young dog, likely histiocytoma, although can get them in older dogs

Question 396

Plasma cell tumour

Answer 396

Rounds cells individually arranged Looks like well differentiated plasma cells, however the cells are predominantly plasma cells. If this was reactive you would see a mix of lymphocytes and plasma cells Prominent golgi zone Multinucleation and Macronuclei even though commonly benign

Question 397

Transmissible Venereal Tumour

Answer 397

Used to be a rare disease in the UK Seeing more and more cases Sexually transmitted tumour is thought to be of histiocytic origin - transfer of intact neoplastic cells Often around the mouth or genital region, but can be seen in other sites. Cytoplasm is characteristic: Abundant light blue to grey with moderate to many discrete margined vacuoles CTVT cells have 59 chromosomes compared with the normal canine karyotype of 78 chromosomes. PCR now available to help diagnosis

Question 398

Neuroendocrine neoplasia

Answer 398

Arrangement Free nuclei arranged in small rosettes / sheets Shape No cytoplasm – mostly just bare nuclei Nuclei Round Exfoliate well Examples: Thyroid tumours, pheochromocytomas

Question 399

Cytology Description and Identification

Answer 399

Identification: Nuclear features- Size and shape Chromatin Nucleoli Nuclear membrane Relationship / nuclear moulding Mitotic figures Cytoplasmic features- Vacuolation Basophilia Product N:C ratio Nuclear position Miscellaneous Background – joint fluid, product, mucous, chylous Haemodilution – inflammatory? Accompanying cells – contamination or tissue? Concurrent process – haemorrhage, inflammation, necrosis Presence / absence – e.g. lymphoid cells

Question 400

Criteria of Malignancy

Answer 400

Anisocytosis and Anisokaryosis Increased nuclear to cytoplasmic ratio (not always seen e.g.: lymphocytes) Nuclear features: Mitotic figures, how many there are and if they are atypical Multinucleation Nuclear moulding Angular nuclei Chromatin (instead of being smooth it becomes coarse and clumped) Nucleoli: Prominent, multiple, angular, anisonucleoliosis Macrocells, macrokaryosis and macronucleoli - macro is always bad news! Necrotic cells in between neoplastic cells. These cells look like smudge cells (been rubbed out with a rubber) Phagocytosis - cannibalism Emperipolesis Crowded cells

Question 401

Anisokaryosis

Answer 401

one of the main features of cancer cells: variation of nuclear size and shape from cell to cell. Referred to as nuclear pleomorphism and anisonucleosis.

Question 402

Nuclear moulding

Answer 402

conformity of adjacent cell nuclei to one another. It is a feature of small cell carcinomas and particularly useful for differentiation of small cell and non-small cell carcinomas, i.e. adenocarcinoma and squamous carcinoma.

Question 403

Emperipolesis

Answer 403

the presence of an intact cell within the cytoplasm of another cell. It is derived from Greek (en is inside, peripoleomai is go round). Emperipolesis is an uncommon biological process, and can be physiological or pathological.

Question 404

Lymphoma subtyping – Cytological criteria

Answer 404

Features of the abnormally represented population: Small, intermediate or large lymphocytes Blastic appearance (presence or absence of nucleoli) Position of the nucleus in the cell, eccentric or central Shape of the nucleus, round, oval, cleaved, convoluted Relative volume of cytoplasm Appearance of cytoplasm, eccentric, concentric, mirror-handle Presence/absence of golgi zone Relative numbers of mitotic figures and presence of atypical mitoses Dimorphic lymphocyte distribution Presence of ancillary cells, tingible body macrophages, eosinophils Careful cytological assessment will efficiently diagnose lymphoma and allow estimation of the classification, phenotype and grade PARR analysis Assessment of clonality (genotype) Clonality Testing (PCR for antigen receptor rearrangement; PARR) uses end-point PCR to predict whether lymphocytes in a sample are a clonal or polyclonal population Flow cytometry Assessment of phenotype Immunocytochemistry Assessment of phenotype

Question 405

Mechanisms of cell injury

Answer 405

Anything that causes cell injury disrupts cellular homeostasis. Cells can be injured by myriad causes, both from intrinsic and extrinsic sources. Damage occurs to cells through one or a combination of of four basic mechanisms: Adenosine triphosphate (ATP) depletion Permeabilization of cell membranes Disruption of biochemical pathways, especially those of protein synthesis DNA damage

Question 406

Morphology of cell injury

Answer 406

The common appearance of an injured cell is swelling Due to Failure of ATP-dependent enzymes and pumps/channels Increased membrane permeability Acute cell swelling is also known as hydropic degeneration Particularly in the liver (hepatocytes) and kidney(renal tubular epithelial cells In other cell types such as the skin (keratinocytes), cell swelling from influx of water is called ballooning degeneration. Can be reversible if inciting factor/agent is gone Three key histopathological changes in acute early and reversible cell injury visible with light microscopy are: Cell swelling Cytoplasmic vacuolation Hypereosinophilia Organelle changes, membrane blebs and myelin figures are typically only seen using ultrastructural examination (transmission electron microscopy)

Question 407

Hydropic degeneration

Answer 407

extensive fluid accumulation

Question 408

Fatty change

Answer 408

Physiology of lipid metabolism Lipid is delivered to the hepatocyte from dietary sources or body fat stores in the form of free fatty acids (FFAs). A small amount of FFAs are also synthesized in the hepatocyte itself from acetate. Some of the FFAs are utilized for the synthesis of cholesterol and phospholipids, and some may be oxidized to ketone bodies (1). Most of the intracellular FFAs are esterified to triglycerides (2). Once triglycerides are produced, they must be complexed to a lipid acceptor protein (or apoprotein) prior to export from the cell (3) as lipoproteins. This requires protein and energy Triglycerides may accumulate if the balance between the synthesis of triglycerides and their utilization or mobilization is deranged. When intracellular triglycerides accumulate, a fatty liver results. Hypoxia Protein synthesis Aflatoxin Carbon tetrachloride

Question 409

Outcomes of cell injury

Answer 409

Four possible outcomes Repair Adapt Senescence Death Dysplasia -> neoplasia Unsurprisingly, mitochondria, which are the organelles most susceptible to injury, are thought to direct many of the processes of cellular adaptation, senescence, and programmed death. The point at which reversible cell injury becomes irreversible is debateable, but likely is dependent on calcium homeostasis within the cell

Question 410

cell adaptations

Answer 410

In the face of chronic sub-lethal injury (or stressor), cells can adapt involving the following mechanisms: Hypertrophy an increase in cell size by virtue of an increase in number and size of organelles Hyperplasia an increase in cell number that only those cells capable of mitosis can undergo Atrophy a decrease in cell size by virtue of a decrease in number and size of organelles Metaplasia a change from one differentiated cell type to another of the same germ layer (e.g., from ciliated epithelium to stratified squamous epithelium in the respiratory tract) Dysplasia abnormal differentiation with features of cellular atypia These are physiologically normal responses, however can result in their own pathologies.

Question 411

Senescence

Answer 411

Senescent cells are somatic cells that stop dividing Senescent cells remain metabolically active Signals that induce senescence are typically due to DNA damage and/or tumour suppressor genes p53-p21 p16

Question 412

Morphological appearance of cell ageing

Answer 412

Long-lived post mitotic cells Neurones and muscle Lipofuscin Senescent cells Heterochromatin accumulations Transmission electron microscopy Not clinically relevant Biochemical markers of senescence Lack proliferation markers Senescence-associated secretory phenotype (SASP) Research orientated

Question 413

Lipofuscin

Answer 413

Wear-and-tear pigment Normal accumulation over time of lipoprotein in secondary lysosomes May accumulate excessively in certain circumstances Phalaris poisoning in ruminants Intracellular, golden-brown, globular Ceroid Very similar to lipofuscin but only accumulates in disease states Brown gut in dogs with vitamin E deficiency Intracellular and extracellular

Question 414

Endogenous pigmentation – non-haematogenous

Answer 414

Lipofuscin and ceroid Melanin Incidental colouration Leptomeninges Pig lungs - melanosis Hyperpigmentation Endocrine skin disease Melanoma Hypopigmentation Vitiligo Melanin incontinence Some skin diseases of dermo-epidermal junction (pemphigus)

Question 415

Endogenous pigmentation - haematogenous

Answer 415

Blood Haemoglobin Haemosiderin- brown iron-containing pigment usually derived from the disintegration of extravasated red blood cells. It tends to be golden brown, more refractile, and more clumped than melanin Haematoidin- an orange-yellow pigment in the bile that forms as a product of hemoglobin; excess amounts in the blood produce the yellow appearance observed in jaundice Porphyria- Heme synthesis disorder Deposition of porphyrin pigments in tissues Methaemoglobinaemia Heme iron is oxidized from the ferrous (2+ ) to the ferric (3+ ) form Methaemoglobin is constantly being formed, but it is reduced to haemoglobin by the methaemoglobin reductase pathway Marked oxidant exposure may promote the formation of methaemoglobin.  Oxidative agents include gallotannin metabolites Red Maple/Acer  Associated with Heinz bodies (see haematology lectures next week) May also see haemolytic crisis The blood and mucous membranes may appear brown when >10% of the total hemoglobin has been converted to methemoglobin Rare genetic disease in humans Carbon monoxide CO bind haemoglobin, forming carboxyhaemoglobin Much stronger binding than oxygen and slow to revert Cherry red mucous membranes, muscle and brain

Question 416

Carotenoids

Answer 416

Exogenous pigmentation found in leafy vegetables and in horses and Jersey cattle impart a yellow colour to adipose tissue and lipid-laden organs.

Question 417

Calcification

Answer 417

Pathological calcification = deposition of calcium salts in soft tissues - typically as phosphates and carbonates Metastatic calcification is due to increased circulating calcium levels Dystrophic calcification is secondary to necrosis

Question 418

Morphology of necrosis

Answer 418

Continued swelling and hypereosinophilia Nuclear changes Pyknosis = shrinkage Karyorrhexis = fragmentation Karyolysis = dissolution Inflammation

Question 419

Causes of necrosis - anoxia

Answer 419

Reduction or cessation of ATP production due to hypoxia or anoxia respectively will result in loss of function on energy-dependent cell pumps Na+/K+ pumps Discussed in POP lecture 1 Results in cell swelling due to osmotic pressure ONCOTIC NECROSIS Cell swelling is the typical feature and distinguishes it from apoptosis Calcium efflux pumps are also affected resulting in accumulation of intracellular calcium

Question 420

Causes of necrosis – membrane damage

Answer 420

Membranes can be directly damaged by Pore-forming infectious agents/toxins Reactive oxygen species (ROS) Phospholipase activation Protease activation One of the best examples of membrane damage by pore-forming toxins are those produced by Clostridium perfringens

Question 421

Causes of necrosis – free radicals

Answer 421

Free radicals are any molecule with a free electron Reactive oxygen species (ROS) and reactive nitrogen species (NO) Produced by oxidative metabolism, therefore most frequently made by mitochondria, but will also damage the mitochondria if cannot be removed. Vitamin E and selenium are important co-factors in the neutralisation of free radicals

Question 422

apoptosis

Answer 422

Apoptosis is normal Embryological Physiological May be due to a pathological process Organ not receiving stimulus portosystemic shunt Cell contains infectious agent Cell is irreparably damaged DNA is irreparably damaged Cell is cancerous Two main mechanisms of apoptosis Intrinsic Extrinsic Morphology differs to necrosis Cell is shrunken No/minimal inflammation Chromatin condensation around nuclear periphery (most characteristic) Formation of cytoplasmic blebs = apoptotic bodies There are different types of programmed cell death

Question 423

Liquefactive/lytic necrosis

Answer 423

Cells are lysed, and the necrotic tissue is converted to a fluid phase Caused by: Bacteria Fungi Cryptococcus neoformans in the brain Most common in the CNS Due to hypoxia Large amount of cells and cell membranes with little connective tissue Gross Soft, viscous focus, often with cavity containing creamy-yellow material (pus). Histo: Cell debris, eosinophilic fluid Very messy

Question 424

Coagulative necrosis

Answer 424

Tissue architecture/basic outline of necrotic cells is preserved Suggestive of hypoxic injury bacterial toxins chemical toxins Gross Often well demarcated Especially if due to infarction Rim of inflammation Histo Overall tissue architecture preserved, often with retention of basement membranes Necrotic cells display typical histologic evidence of necrosis Inflammation Early attempts at healing Especially in kidney if basement membrane intact

Question 425

Caseous necrosis

Answer 425

Cheese-like A chronic coagulation necrosis Typically due to body’s inability to remove the agent Intracellular bacteria Common in birds and reptiles Reduced amounts of myeloperoxidase in heterophils. Gross: Friable, granular, white appearance Typically encapsulated Abscess/granuloma/pyogranuloma Histo: Loss of architecture Central accumulation of remnants of lysed leukocytes May have border of granulomatous inflammation and outer fibrous tissue (‘granuloma’) Often dystrophic calcification centrally. A classic bacterial example is Corynebacterium pseudotuberculosis

Question 426

Gangrenous necrosis

Answer 426

Often a sequel of coagulative necrosis Three types Wet/moist: Area of necrotic tissue further degraded by liquefactive action of saprophytic bacteria. Death of animal may occur due to toxaemia/ sloughing of tissue Gross: soft, moist, red-brown to black. +/- gas, putrid odor (hydrogen sulfide). Gaseous: Bacteria proliferate and produce toxins in necrotic tissue. Usually anaerobic bacteria eg. Clostridium perfringens/ septicum. Bacteria introduced by penetrating wounds, necrotic tissue becomes anaerobic, bacterial growth and toxin production. Gross : dark red-black, gas bubbles, fluid and haemorrhagic exudate. Dry: Coagulation necrosis secondary to infarction followed by mummification (dehydration). Usually lower portion of extremity (tail, ears, udder). Ingested toxins- ergot, fescue, and frostbite. Peripheral arteriolar constriction and damage to capillaries. Thrombosis and infarction (also direct freezing injury and ice crystal formation in frostbite). Necrotic tissues depleted of water eg. by low humidity, resulting in mummification. NO bacteria proliferation. Gross: dry, shrivelled, brown-black. May slough.

Question 427

Fat necrosis

Answer 427

Nutritional, enzymatic, traumatic, and idiopathic. Focal areas of fat destruction. Nutritional fat necrosis Also known as steatitis or yellow fat disease Diet high in unsaturated fatty acids and low in vitamin E or other antioxidants ROS production and lipid peroxidation. Enzymatic necrosis of fat Pancreatitis Release of activated pancreatic lipases which liquefy adipocytes Fatty acids combine with calcium to form chalky white areas (saponification) Faint outlines of cells with basophilic calcium deposits and inflammation Traumatic necrosis of fat Crushing Idiopathic fat necrosis Necrosis of abdominal fat of Jersey/ Guernsey breeds Large masses of necrotic fat in mesentery, omentum and retroperitoneum. May cause intestinal stricture/stenosis. Gross: Firm, white, chalky. Histo: Necrotic fat not lost in processing. Eosinophilic to basophilic (if FFA’s react with Ca2+ to form soap) necrotic adipocytes.

Question 428

Fibrinoid necrosis

Answer 428

Blood vessels associated with inflammation = vasculitis Antigen and antibody complexes deposition in arterial walls and fibrin leakage. Histo: Bright pink, amorphous hyaline (glassy) Thrombosis

Question 429

Oedema

Answer 429

Changes in the distribution of fluid between the plasma and interstitium are most commonly manifested as oedema, which is defined as accumulation of excess interstitial fluid. Occurs by: increased microvascular permeability increased intravascular hydrostatic pressure decreased intravascular osmotic pressure decreased lymphatic drainage

Question 430

Increased intravascular hydrostatic pressure results in

Answer 430

Increased flow or volume of blood hyperaemia (active) congestion (passive)

Question 431

Acute inflammation – serous exudation

Answer 431

Exudation of cell-poor fluid into spaces created by cell injury or into body cavities (effusions) Fluid is not infected & does not contain high numbers of leukocytes. Seen with: Thermal injury to skin - blisters Acute allergic responses - watery eyes/runny nose

Question 432

Acute inflammation – Catarrhal/mucoid exudation

Answer 432

Secretion of thick gelatinous fluid Contains mucus and mucins Occurs most commonly in tissue with abundant goblet cells & mucous glands – runny nose

Question 433

Acute inflammation – Fibrinous exudation

Answer 433

Characteristic of inflammation of membranes of body cavities and organs meninges, pericardium, joints Most commonly caused by infectious microbes

Question 434

Acute inflammation – Suppurative/purulent exudation

Answer 434

Pus = an exudate consisting of neutrophils, the liquefied debris of necrotic cells, and oedema fluid. The most frequent cause = infection with bacteria that cause liquefactive tissue necrosis e.g. Staphylococci - aka pyogenic (pus-producing) bacteria.

Question 435

Haemoperitoneum

Answer 435

blood in the peritoneal cavity

Question 436

Haemothorax

Answer 436

blood in the thoracic cavity

Question 437

Haemopericardium

Answer 437

blood in the pericardial sac

Question 438

Aneurysm

Answer 438

= bulge in an artery due to defect in the wall

Question 439

Thrombus

Answer 439

A thrombus forms antemortem within a vessel A thromboembolism is a section of a thrombus that has broken off and lodged elsewhere An antemortem clot is a coagulum of blood and/or plasma that forms when bleeding into a cavity  Post mortem clots are found within vessels and the heart and are a product of blood stasis and clotting post mortem  Abnormal blood flow Valvular disease Heart disease Shunts Aneurysms Hypovolaemia Torsions Hypercoagulability Glomerular disease Loss of antithrombin 3 Metabolic disease Inflammation Platelet activation Neoplasia Endothelial injury Infectious diseases Free-radicals vit e/selenium deficiency Toxins Trauma

Question 440

infarction

Answer 440

An infarct is a local area of very acute (peracute) ischemia that undergoes coagulative necrosis.  Infarction is caused by the same events that result in ischemia and is most common secondary to thrombosis or thromboembolism.  The characteristics of an infarct are variable based on the type and size of vessel that was occluded (artery or vein), the duration of the occlusion, the tissue in which it occurs, and the prior perfusion and vitality of the tissue.

Question 441

Abscess and granulomatous inflammation

Answer 441

Abscesses form due to Production of myeloperoxidase by neutrophils which themselves also undergo necrosis, resulting in liquefaction and pus Rabbits and birds lack myeloperoxidase, resulting in an inability to form pus Chronically, fibroblasts produce collagen and extracellular matrix proteins to wall off the area = fibrous capsule Granulomatous inflammation occurs when the inciting agent cannot be removed and is largely mediated by macrophages which may become multinucleated or epithelioid Granulomatous inflammation can be Nodular = (tuberculoid) granulomas Mycobacterium bovis Diffuse = lepromatous Eosinophilic granuloma Mycobacterium leprae

Question 442

Healing

Answer 442

Repair and healing are defined loosely as restoration of tissue architecture and function after an injury Repair (parenchymal and connective tissues) Healing (surface epithelia) Two mechanisms REGENERATION: some tissues are able to replace damaged components and essentially return to a normal state occurs by proliferation of cells that survive the injury and retain the capacity to proliferate In some cases, tissue stem cells may contribute to restoration of damaged tissues (mammals have limited capacity to regenerate damaged tissues/organs) i.e. in the rapidly dividing epithelia of the skin and intestines and in some parenchymal organs, notably the liver. Requires an intact basement membrane CONNECTIVE (FIBROUS) TISSUE DEPOSITION Occurs when injured tissue incapable of complete resolution or if supporting tissue structure is severely damaged May result in scar formation – not normal but provides enough structural stability that the injured tissue is usually able to function Fibrosis: describes the extensive deposition of collagen that occurs in the lungs, liver, kidney, etc. as a consequence of chronic inflammation or in the myocardium after extensive ischemic necrosis (infarction) Macrophages play a central role in repair by clearing offending agents and dead tissue, providing growth factors for proliferation of cells secreting cytokines that stimulate fibroblast proliferation and connective tissue development Repair begins within 24 hours after injury with emigration of fibroblasts and induction of fibroblast and endothelial cell proliferation. Angiogenesis (formation of new blood vessels) – supplies nutrients/oxygen for repair; vessels are leaky because VEGF (GF that drives angiogenesis) increases vascular permeability; also due to incomplete interendothelial junctions Formation of granulation tissue – consists mainly of fibroblasts and new capillaries in a loose ECM often admixed with inflammatory cells (mainly macrophages); progressively invades site of injury; amount formed depends on size of tissue deficit and intensity of inflammation Remodelling of connective tissue (produces stable fibrous scar) – process of maturation of the connective tissue. The amount increases gradually leading to reorganisation and formation of a scar.

Question 443

Ethylene Diamine Taetra-acetic Acid (EDTA) is usedfor

Answer 443

Haematology

Question 444

Lithium Heparin is used for

Answer 444

biochemistry

Question 445

blood tubes without an addiive are use for

Answer 445

All serum tests

Question 446

Sodium Fluoride/Potassium Oxalate blood tubes are used for

Answer 446

Blood glucose

Question 447

Trisodium Citrate (Sodium Citrate) blood tubes are used for

Answer 447

Coagulation studies Prothrombin test