Clinical Pathology Flashcards

Question

What is the order of draw for vacutainer blood collections?

Answer 1

Serum (red), Citrate (Blue), EDTA (purple), OXF (Grey) Red/blue can be swapped

Answer 2

1. Backflow: Regurgitation of tube blood into needle or vein via decreased vein/digital pressure 2. Decant: Insufficient blood in serum tube, it is fixed via pouring/mixing bloods from other tubes 3. Lab Tech Error: Incorrect Sample is used

Answer 3

Fast for 12 hours prior to blood collection to avoid lipaemia as it may lead to sample haemolysis Interfere with spectrophotometer & inaccurate Hb/erythrocyte haematology

Answer 4

Blood mixing: The percentage of blood composed of erythrocytes/RBC's Method: Collect by EDTA/Heparin tube and fill up 3/4th micro-capillary tube, plug one end with plasticine and centrifuge RBC's have the highest specific gravity of the cells in blood and therefore gravitate to the bottom of the capillary tube during centrifugation, to appear as a dark red column. PCV: Packed cell volume: Percentage of whole blood composed of RBCs Anticoagulant collection (EDTA or Heparin)

Answer 5

Align the bottom of the red cells with the zero value, and the top of the plasma with the 100 line. Move the dial, to measure where the top of the red cells are. - Packed RBC's (bottom) : Higher specific gravity --> Sink - Buffy Coat (middle) : WBC, platelets, mast cells & microfilaria - Plasma: Total plasma protein Yellow: Icterus or carotene pigments with diet Red: Increased Hb, in-vitro (Collection/lipemia - normal PCV), in vivo (IV haemolysis) White/opaque: Lipemia: Either post-grandial or abnormal lipid metabolism

Answer 6

TPP is true plasma protein A refractometer estimates the concentration of solute in fluid via the bending light relative to distilled water Measures total plasma protein Results: Increased PCV & TP - Clear: Dehydration Decreased PCV & TP - Clear: Blood loss Decreased PCV and Increased TP: Red: intavascular haemolysis Decreased TP and Increased PCV: Clear/yellow: extravascular haemolysis

Answer 7

1. Quantitative Buffy Coat Systems: Spins down sample in a tube and based on specific gravity (Density-gradient centrifugation), separates them into layers and adds a special stain (Acrdine orange dye). Separates and counts cells Order: Platelets, monocytes/lymphocytes, granulocytes, PCV 2. Impedance analysers - Coulter Counter Blood cells pass through an electrical aperture & impedes current flow generating a pulse The longer the impedance, the bigger the cell 3. Laser-based Flow Cytometers: Combination of impedance, laser flow cytometry & stains Assess size/internal complexity by measurement of light scatter

Answer 8

Definitions: - RBC (x1012/L): Number of red blood cells - HCT - Haematocrit (L/L): RBC vol. per L of blood, equivalent to as PCV Calculation: PCV/100 Difference: HCT < PCV (0.01-0.03L) – due to no trapping of plasma between RBCs HCT is the percentage of blood volume filled by platelets. - HGB - Haemoglobin (g/L): Concentration of Hb - MCV – Mean Cell Volume (fL): Average RBC size Calculation: (HCT x 1000) / RBC Issue: Does not show range of variation cf. RDW - MCHC – Mean Cell Hb Conc (g/L): Average concentration of hb per RBC Calculation: HGB/HCT - RDW (%): Coefficient of variation for RBC size Calculation: (SD MCV/MCV) x 100 Adv: More descriptive cf. MCV - Reticulocytes (x109/L): Absolute reticulocyte concentration

Answer 9

1. Group RBC, Hb and & Haematocrit together 2. Haematocrit should be 3x the haemoglobin concentration. 3. Increased MCHC can be used to identify errors as It is not physiologically possible to have excess haemoglobin. 4. If either of these are skewed use PCV and blood smear evaluation to identify issues: if it is an artefact or an error. a) Manual PCV: If HCT does not equal PCV, then there is an increased MCV (aging, agglutination), increased RBC (Platelet included). If plasma coloured red (haemolysis) or Opaque (Lipemia) b) Blood smear: Increased MCHC --> Heinz bodies, spherocytes, eccentrocytes Occur in diseases causing oxidative damage to the red cell

Answer 10

- ↑ RBC, HgB, HCT: Polycythemia (Erythrocytosis) - ↓ RBC, HgB, HCT: Anaemia - ↑ MCV: Macrocytosis, e.g., Regeneration, FeLV, Artefact (Agglutination/aging) - ↓ MCV: Microcytosis, e.g., Iron deficiency, PSS - ↑ MCHC: Error - ↓ MCHC: Hypochromasia, e.g., Chronic blood loss - ↑ RDW %: Sig. macro/microcytosis or regeneration

Answer 11

Examines the different types of white cells. The WBC differential count determines the number of each type of white blood cell, present in the blood. Can be expressed as a percentage (to total WBC), can be misleading, or absolute value (% x total WBC x 100)

Answer 12

nRBC = nucleated RBC TNCC = Total nucleated cell count When there is greater than 5 nRBC/100WBC Method 1: Machine TNCC x (100 / nRBC + 100) Method 2: Correct WBC = initial WBC - (nRBC)

Answer 13

PLT: Platelet Count MPV: Mean platelet volume PDW: Platelet distribution width (PDW) Plateletcrit (Thrombocrit) - ↑ PLT: Thrombocytosis, e.g., Physiological (Epinephrine splenic contraction), 2nd inflam/neoplasia, iron deficiency - ↓ PLT: Thrombocytopenia, e.g., <30 x 109 can cause spont. Haemorrhage - ↑ MPV: Immature platelets suggesting thrombopoiesis

Answer 14

Collection: EDTA > 1/2 full, unless small patients then fill completely Make 2x smears EDTA is anticoagulant of choice Heparin: Discouraged as cells can clump and invalidate counts, stain incompatability Citrate: Cannot be used as it dilutes the cells

Answer 15

Transit: Keep EDTA in fridge until transport with a cold pack, Don't place smears in fridge/formalin Role: - Check for platelet clumps - Estimate WBC - Assess RBC - Identify parasites

Answer 16

Method: Wedge slide by Maxwell Wintrobe - Place drop of blood from EDTA from capillary tube or wooden stick ~3mm in size - Place spread slide at 30–45-degree angle, drawn backwards first to distribute blood - Spread forward at a 45-degree angle in a single motion Preparing the stain: Preparation – Romanowski Stain: Dip 4-5x for 2s each → Fixative (Methanol) → Acidic dye (Eosin) → Basic dye (Methylene) Basic care: Wipe slides between each jar, keep sealed & regularly replace, write date on jar PARTS OF A BLOOD SMEAR: - Application point - Body - Monolayer - Feathered Edge

Answer 17

1. On 10x: Assess smear quality Feathered edge look for platelet clumps, parasites, large or neoplastic cells, WBC clumping 2. On 100x: Estimate platelet count and observe platelet morphology Feline platelets prone to clumping Monolayer/Feathered Edge 3. On 10x: Estimate WBC count Count number of WBC in 3 (10x) fields in the monolayer. Divide by 3 to get the average. Divide by 4 to get white cell concentration. and 100x perform WBC differential count: Tallying, differential grid, manual cell counter Count neutrophils, band neutrophils, lymphocytes, monocytes, eosinophils, basophils 4. Scan on 10x for erythrocyte distribution and 100x for morphology - Assess density, shape, colour, size, regeneration/cell types Rouleaux: Linear branching/non-branching aggregates resembling stacked coins Common in horses, less in cats Formed via interactions between RBC membranes and plasma macromolecules. Increased rouleaux with hyperglobulinaemia and hyperfibrinogenaemia Aggregates due to agglutination (RBC being held together via antibodies). Immune-mediated response --> Saline Dispersion/Dilution Test: Disperse RBC aggregates into individual with TPP is diluted Density/Anaemia: Reduced RBC density or increased space between RBC Morphology: Size: Microcytes, macrocytes, anisocytosis (Different sizes) Shape: Round, or poikilocytes

Answer 18

Neutrophils: Sausage shaped nucleus, granules on the cytoplasm Band neutrophil: Shaped like a horseshoe Lymphocytes: Round nucleus. Metarubicyte: Purple, poly cytoplasm Natural killer cells: High amount of granules in the cytoplasm Blue: producing protein Monocytes Basophils: Purple or lavender coloured granules Eosinophils: Bubbly looking

Answer 19

Canine: Largest in size, greatest in central pallor Feline: Second largest, minimal central pallor, rouleaux/aniscocytosis mild Equine: Mid range, central pallor. Prominent rouleaux, no anisocytosis Bovine: Smaller in size, central pallor, no rouleaux, aniscocytosis

Answer 20

Immature RBC that contains RNA (Ribosomes). Indicates regeneration Cause: Normal dogs & cats in low numbers (1-1.5%) BUT not in horses/ruminants

Answer 21

Aggregate Reticulocyte: Immature RBC with RNA precipitate visualised with methylene blue stain – appear polychromatophilic in normal stain Cause: Indicate regenerative response Punctate Reticulocyte: More mature form of reticulocytes with lower ribosomal material (~2 Discrete granules) – Appear normochromic in normal stain

Answer 22

Decreased/inhibited Hgb production Cause: Seen in normal young animals or Iron & copper deficiency or zinc excess

Answer 23

Schistocytes: RBC fragments due to shearing caused by vasculature abnormalities (e.g., Blood flow, Fibrin) or RBC fragility (e.g., Iron deficiency) Keratocytes: Fragmentation injury Physiological: Low no. in healthy cats Causes: Liver dz (Cats: Hepatic lipidosis), EDTA, Fragmentation, Oxidant injury Spherocytes: Removal of RBC membrane by macrophages causing sphered RBC Causes: IMHA, Fragmentation, Snake envenomation, Histiocytic sarcoma Acanthocyte: Irregularly space, variably sized spicules ending in club or fist shapes Causes: DOGS – Dz of fragmentation (E.g., HSA, Liver dz, DIC, GN), GOATS – Normal if young Biomarker: For HSA in Dogs Mechanism: Unknown – lipid composition of RBC?

Answer 24

Agglutination: Clumping of RBC due to Ab bridging Causes: EDTA artefact, heparin therapy (Horses), IMHA (IgM/IV) Ghost Erythrocyte: Lysed RBC via rupture of membrane causing Hb release, leaving the membrane Cause: Sample artefact, IV IMHA, Babesia, Zn toxicity (Dog), neonatal isoeryhrolysis Eccentrocyte: Mature erythrocytes where the Hgb is pushed to one side of the cell – opposite pale stain Causes: Oxidation causes bonding of RBC membranes → collapses & Hgb is displaced

Answer 25

Cause: Regenerative anaemia, corticosteroids or physiological in low no. (horse and Cats)

Answer 26

Definition: Increased RBC in peripheral blood Parameters: Increased RBC, Hgb, HCT CS: Purple mucous membranes, congested retinal blood vessels, seizures Consequences: Sludging blood, impaired blood flow, poor tissue oxygenation

Answer 27

Splenic Contraction Cause: Adrenal mediation --> Excitement, fear, exercise Clinical tissue: TPP is normal + Physiological leukocytosis, mature neutrophilia, lymphocytosis Adrenalin causes the spleen to contract, red cells released into the circulation. When adrenalin disappears, the changes go away --> Transient.

Answer 28

Increased RBC, HgB, HCT Primary erythrocytosis: Erythroid Neoplasia/Polycythaemia Vera Neoplasia of erythroid, myeloid, megakaryocytic cell lines Neoplasia that causes cell lines to increase. Erythropoietin is normal: as it is a tumour does not need erythropoietin for stimulus for increase in RBC production. Secondary Erythrocytosis: Appropriate SE: Hypoxia erythrocytosis. - Cardiac failure, respiratory disease or hyperthyroidism Blood is passing kidney, kidney detects not enough oxygen, increase erythropoietin to increased RBC production Inappropriate SE: Renal neoplasia, non-renal neoplasia.

Answer 29

Increased conc of blood components due to decreased plasma volume Dehydration CS: TPP is elevated (albumin), RBC is the same Endotoxic Shock Shift of fluid from intra to extravascular e.g. Vessel damage, osmotic gradient CS: Inflammatory leukogram

Answer 30

Complete set of numerical data and any morphological abnormalities noted on blood smear. Detect inflammatory disease, haemtopoietic neoplasia Limitations: Can not identify specific aetiological agents and cannot indicate site of inflammation Cannot determine if it is chronic, mild or non-invasive inflammation

Answer 31

Reduction (Penia): Neutropenia Lymphopenia Eosinopenia Increase (Philia or cytosis) Neutrophilia Lymphocytosis Eosinophilia Monocytosis

Answer 32

Common in dogs: Fight or flight response Blood vessels have a marginal and a central pool When adrenalin is released, the marginal pool shrinks and the central pool gets bigger. Dogs have a big central pool and a small marginal pool Whereas cats have a large marginal pool, thus are prone to physiological induced leucocytosis. Adrenaline: Causes decrease adherance of lymphocytes and neutrophils to the blood vessel walls. Adrenalin is causing increased blood flow, making the central pool bigger. As neutrophils are less adhered, they move to the central pool and there increased flow of lymphocytes to blood vessels, tissues and lymph nodes. There is neutrophilia and lymphocytosis. URL: Upper reference limit Magnitute of neutriphilia 2 x URL (dogs horses, cattle) 3 x URL in cats due large marginal pool Magnitude of lymphocytosis: 2 x URL: common in cats, horses

Answer 33

Steroidal stress leukogram can be because of extreme stress, endogenous or exogenous steroids E.g. Cushings: Extreme cortisol excess. has a classic pattern of neutrophilia, lymphopenia, monocytosis and eosinopenia Neutrophilia is due to steroids changing neutrophil kinetics: 1. Production of neutrophil adhesion molecules are down regulated, double neutrophils (canine, equine, boine) and greater than in cats due large MNP 2. Increased release of mostly mature neutrophils from the storage pool 3. Hyper segmentation

Answer 34

Disease causes lower than normal production of cortisol by adrenal glands Neutrophils low Lymphocytes high Monoctyes normal Eosinophils high

Answer 35

Cell maturation proceeds from left to right A shift to the left means more immature cells A shift to the right means more mature/aged cells Neutrophils Mature neutrophils are segmented Immature are Horse-shoe shaped: Band neutrophils An inflammatory leukogram can be seen to have more immature/band neutrophils because they are pulling earlier cells into circulation to deal with the inflammation. Left shift: An increase in immature neutrophils and is usually a sign of inflammation Degenerative Left shift: Band neutrophil count is higher than the mature segmented neutrophil count Bone marrow is not coping with the inflammatory process. *Cattle: A degenerative left shift may not be poor prognosis as neutrophils leave the blood to gather at side of inflamm

Answer 36

Toxic change is in the presence of severe inflammation. There is defective maturation due to accelerated bone marrow production Produce very immature cells that are toxic cells.

Answer 37

Cytoplasmic basophilia: Cytoplasmic RNA & ribsomes retained Dohle Body Inclusions: Retained rough ER grey-blue round aggregates in the cytoplasm Cytoplasmic Vacuolation: Loss of granule & membrane integrity Toxic Granulation: Retention of mucopolysaccharides & ↑ permeability of primary granule membranes to romanowsky stains (Pink) – DO NOT confuse w/ secondary granules

Answer 38

Neutrophilia: Release from storage pool. Left shift can occur with depletion of storage pool Dogs/Cats: Common to see neutrophilia as they have a higher bone marrow reserve. Will release if there is an inflammatory stimulus If there is neutropenia is it a very severe lesion. Horses/Cows: Slower to release as there is less capacity.

Answer 39

Extreme inflammation, a lot of white cells in peripheral bloods.

Answer 40

Increased margination and emigration of lymphocytes to inflamed tissue Lymphocytes to lymph noes and reduced exit of lymphocytes from lymph nodes Therefore it is LYMPHOPENIA Monocytosis as neutrophils have common stem cell with other monocytes As there is neutrophila there is no monocyte bone marrow storage pool (released earlier). Recovery when there is neutropenia.

Answer 41

Neutrophilia initially. If the inflammation becomes overwhelimg there is neutropenia due to supply not meeting demand, left shift. Lymphocytosis: Lymph nodes struggle in its production of lymphocytes Common in young animlas

Answer 42

Shift: Neutropenia, Eosinopenia, Lymphopenia Pathogenesis: - Inflammatory Neutropenia: ↑ Margination & emigration to tissues > Release from BM Shift: Within hours of infection - Left shift, 2d post infection - ↑ BM stimulation Incidence: Common in cattle (Small storage & slow BM response) +- Horses - Endotoxic Neutropenia: 1-3hrs: Rapid shift from CNP (Central pool) to MNP via ↑ endothelial adhesion 8-12hrs: Released neutrophils from BM 3-5d: Neutrophilia due to ↑ production Importance: Neutropenia is seen depending on the time samples are taken

Answer 43

Eosinophilia Causes: - Hypersensitivity, e.g., Flea bite - Mast cell degranulation, e.g., Skin, RT, GT, UT - Idiopathic conditions - Parasites, e.g., Tissue migration ONLY - Addison’s - Eosinophilic leukaemia Basophilia Cause: Imprecise leukocyte differential counts OR allergic, parasitic, neoplasia Only a substantial or persistent mild increase is significant Mastocythemia: Cats: Seen with systemic or splenic mastocytosis Dogs: assosciated with inflammatory conditions

Answer 44

It is a decrease in RBC, Hgb, HCT/PCV CS: Weakness, tachypnoea, decreased exercise intolerance, pale MM + Murmur (decreased blood viscosity) Diagnostic Approach: 1. Bone Marrow Response: Determine if the RBC is regenerative or not. Time for bone marrow response: Dogs/Cats: 3-4 days Horses: 4 days Cows: 5-7 days 2. Erythrocyte Indices 3. Pathophysiological

Answer 45

1. Automated Haemogram: Specific: Absolute reticulocyte count Method: Count aggregate reticulocytes, except mild/cr. anaemic cats → count punctate Calculation: Reticulocytes x RBC x 1000 = x109 Results: Dogs - >60-80 x 109, Cats - >50 x 109 is evidence of regeneration - Non-Specific: Elevated MCV (In horses), RDW

Answer 46

Blood Smear: - Specific: Polychromatophil, Reticulocytes (NMB – Punctate & Aggregate) - Non-Specific: anisocytosis, Metarubricyte, basophilic stippling (In Ruminants) - Other: Agglutination, spherocytes, Heinz body, eccentrocytes, parasites, acanthocytes, schistocytes, keratocytes

Answer 47

Haemorrhage: Plasma protein concentration/TPP is decreased in per-acute (ECF not replenished) or compensated in chronic (proteins are released) Plasma colour: Clear 1. Acute or Chronic The acute patient with haemorrhage will be collapsed However the chronic patient will not be tired as the body has learned to compensate for low oxygen concentration. 2. Internal vs External If it is internal the animal will recover quicker as all the iron/blood is still in the body and can be reabsorbed into the body/vasculature If it is external it is lost to the outside. Has to reabsorb iron. Haemolysis: TPP is normal or increased Plasma colour is haemolysed or icteric Dx: Urine colour, blood smear, methaemoglobin imaging

Answer 48

Extravascular: Issue with RBC so breakdown occurs in a macrophage in the liver/spleen = ↑ Bilirubin Intravascular: Occurs in blood vessel & releases Hgb → ↑ bilirubin via liver/macrophage AND release of Hb through blood and urine (Hemoglobinemia, haemoglobinuria) Importance: Free Hgb causes tissue injury → I/v kidney = haemoglobinuric nephropathy

Answer 49

Caused by: Reduce rate of erythropoiesis Via Inflammatory disease, renal disease, marrow hypoplasia or aplasia OR Ineffective erythropoiesis Nutritional: Fe, copper, cobalt, folate, vit. B21 FeLV induced erythroid neoplasia --> Vit. b12/cobalt deficiency of FeLV positive cat: Macrocytic normochromic anaemia --> Fe deficiency can lead to microcytosis as compensation. Making smaller cells. Microcytic normochromic anaemia. Also have schistocytes, keratocytes. can be caused by chronic haemorrhage (e.g. parasites, tumours, ulcers) CS: Tarry faeces, parasites, neoplasia, faecal occult blood test Anaemia is mild if it only affects the RBC from the bone marrow Normocytic, normochromic anaemia is when more than 1 cell line has been affected from the bone marrow. Severity and degree of anaemia effects the pathways

Answer 50

MNEL Monocytosis Neutrophilia Eosinophilia Lymphocytosis Hyperglobulinaemia or hyperfibrinogenaemia Acute phase proteins

Answer 51

1. Functional Fe Deficiency: Fe trapped in macrophages 2. Shortened RBC life span due to inflammatory. mediators/oxidative injury 3. Impaired erythropoietin mediated RBC production in bone marrow

Answer 52

Reduced erythropoietin production (kidney is a source of production alongside the bone marrow) Reduced RBC survival time due to reduced toxic clearance by the kidneys Haemorrhage (GIT ulcers)

Answer 53

Mild to moderate normocytic normochromic anaemia Endocrinopathies: 1. Hypothyroidism: low TT4/TT3 --> decreased metabolic rate --> decreased O2 requirements --> Decrease EpO production --> compensate with new homeostasis/metabolic needs met by lower RBC 2. Hypoadrenocorticism Reduced production of RBC in the bone marrow. Cortisol deficiency and cortisol promots RBC production Hepatopathy: Hepatic disease causes mild normocytic normochromic anaemia Increase in liver enzymes Defective protein and lipid metabolism, affects RBC lifespan. Portosystemic shunts: Microcytic normochromic anaemia. Defective protein synthesis, defective Fe transport and thus potential functional Fe deficiency.

Answer 54

Severe normocytic normochromic anaemia Can be caused by: - damage to bone marrow microenvironment due to inflammation, infection Neoplasia Chemotherapeutic agents Hyperoestrogenism (sertoli or granulosa cell tumour or admin. of oestrogen) Bracken fern toxicity

Answer 55

Causes accelerated RBC destruction 1. Immune mediated 2. Erythrocyte metabolic defect a. Oxidative Damage b. Defect in ATP generation 3. Erythrocyte fragmentation 4. Infectious 5. Other

Answer 56

IMHA is caused by antibodies directed against erythrocyte surface- associated immunoglobulin to destroy RBC. 1. Extravascular haemolysis in macrophages removes the erythrocyte 2. It is converted to a spherocyte by the macrophage, removing part of the RBC membrane 3. Ab binds to complement, activates cascade and forms a membrane attack complex (agglutination) It causes a left shift inflammatory leukogram due to hypoxia causing tissue damage. Can be diagnosed with the Coombs test - Direct antiglobulin test

Answer 57

Extravascular: Most likely IgG antibodies against RBC and increased destruction of RBC by splenic macrophages Smear: Spherocytes Intravascular: IgM RBC destruction and complement membrane attack complex (C5b-9) Marked severity Smear: Agglutination, spherocytes --> Ghosts (C5b-9)

Answer 58

- Idiopathic (Autoimmune): Immune response directed at normal self isotypes - Drug Induced: Develops abnormal antigens on the erythrocyte cell membrane - Vaccine - Alloimmune: a) Blood transfusion reactions b) Neonatal Isoerythrolysis:

Answer 59

Immune mediated destruction of RBCs caused by maternal antibodies ingested in colostrum Common in horses, can occur in cats. Timeline: Born healthy (0-8d) → haemolytic anaemia CS: <24-48hrs – Anaemic (PCV 10-20%), icteric (Bili ~20mg), dyspnoea, ↓ suckling, death, Haemoglobinuria/haemoglobinuric nephropathy In cats: Occurs when Queen type B (Anti-A) breeds to Tom type A – kitten at risk if type A/AB

Answer 60

Dx: 1. Smear: Agglutination, anisocytosis, Metarubricyte, Howell-Jolly bodies, ghosts, spherocyte 2. Coomb’s Test: Antiglobulin tests – Not specific as Dx immune Dz 3. Presumptive Evidence: Ab in serum/plasma of dam’s colostrum reacts to foal/sire Ag 4. Jaundiced Foal Agglutination: Pre suckling to assess risk with colostrum ingestion. Monitor decline in colostral antibody over time to determine where it is safe to allow foal to nurse. If it agglutinates in saline control tube: RBC coated with Ab If agglutinates in low dilutions: Check it is not RBC clumping by adding colostrum to Dam's RBC

Answer 61

1. Test mares for antibodies 2. Mate negative mares to negative stallions OR prevent suckling until testing colostrum Ab 3. If Ab positive, give plasma transfusion/other mares colostrum. Keep testing colostrum unti it is below 1:16 titre

Answer 62

a. Oxidative Damage 1. Heinz Body Haemolysis: 2. Eccentrocytic haemolysis 3. Methaemoglobinaemia Anaemia occurs Extravascular: RBC's more rigid as they are less able to pass through splenic sinusoids --> trapped and removed by macrophages Intravascular: More fragile due to damaged membrane: may rupture spontaneously in blood vessels Ag Formation (Heinz body); Heinz body binds to RBC membrane

Answer 63

1. Heinz Body Haemolysis: They are aggregates of denatured HgB caused by oxidative damage. Zinc can cause Heinz bodies as it causes oxidative damage. Pathogenesis: Oxyhaemoglobin --> Methaemoglobin --> Hgb-Fe3+ turns into hemi-chromes or heme-depleted Hgb --> Hemi-chromes precipitate into heinz bodies --> Sulfhydryl groups are oxidised and form disulphide bonds. Stain: NMB - Pale blue protruding round structures on RBC membranes Wrights & Diff Quik – Slightly pale membrane defects/protrusions Cats: Normal <5% Heinz body in spleen Pathogenic: >5% large Heinz bodies/multiple on RBC Causes: - Paracetamol (Acetaminophen): Lack glucuronyl transferase (No conjugation) → reactive metabolites → deplete glutathione → ↓ protection from oxidative injury - Diabetes Mellitus - Ketoacidosis - Hyperthryoidism - Lymphoma - Onion/garlic, benzocaine, propylene Glycol, propofol Dogs – Causes: Onion, garlic, Vit K1/K3, Paracetamol, Moth ball, Zn Horses – Causes: Onion, Maple lead, Phenothiazine Ruminants – Causes: Onion, Ryegrass, Brassica, Cu (Sheep)

Answer 64

Eccentrocytes are mature erythrocytes in which the haemoglobin is pushed to one side of the cell leaving an opposing pale staining region. Forms when Oxidation causes bonding of RBC membranes --> Collapse & Hgb is displaced Causes: Exogenous oxidants: onions, garlic, acetaminophen, propylene glycol, zinc. Stain: Wrights or Diff Quick Endogenous oxidants: in very sick patients e.g. diabetes mellitus

Answer 65

Oxidant overwhelms RBC mechanisms to keep Hgb in reduced state - Oxyhaemoglobin (Fe2) → Methemoglobin (Fe3 – CAN’T deliver O2) Effects: Initially cyanotic (cannot deliver O2), Later as Fe3+ --> 10% mucous membranes appear brown. Causes: Paracetamol (Dog/Cat), onions, Red maple (Horses), Nitrite

Answer 66

1. Hypophosphataemic haemolysis Severe hypophosphatemia may lead to reduced RBC ATP production. This leads to an unstable RBC membrane, causing haemolysis CS: Depressed myocardium, Rhabdomyopathy, seizures, coma, acute respiratory failure 2. PFK & K Deficiency

Answer 67

a) Post parturient haemoglobinuria Hosts: Cattle Cause: 3-8wk post-calving (multi-parous) ↓P bone mobilisation & ↑ P loss via milk Dx: ↓ ATP& Glutathione, moderate-marked IV anaemia haemolysis, hypophosphataemia Ddx: Complicated by concurrent ketosis, generates oxygen radicals → heinz bodies b) Hyperinsulinism ass. hyperglycaemia Hosts: Domestic animals Pathogenesis: Insulin promotes movement of P & glucose in non-RBC cells Diabetic cats: Polyuria --> Hypophosphataemia and haemolysis Can have concurrent ketosis (heinz body). Combination of hypophosphataemia and ketotic haemolytic anaemia. c) Sporadic Hypophosphatemia Hosts: Horses, dogs, cats d) Artefact Via: Bilirubin interference – depends on analyser & method

Answer 68

Smear: Schistocytes, keratocytes, acanthocytes Form when blood is forced to flow through an altered vascular channel or turbulent blood flow. Causes: - Fibrin – Traumatic injury to RBC membrane: Disseminated (Or local), Vasculitis - Membrane lipid changes – Fragility: Haemangiosarcoma Morph: Acanthocytes. If ruptured: regenerative anaemia +- NRBC’s, Schistocytes, DIC) - Rheological (Blood Flow) process: Cardiac valvular disease (E.g., Endocarditis), Dirofilariasis

Answer 69

RBC's that appear to have one or more intact or ruptured clear "vesicles". If they rupture: Looks like it has one or two projections. When it is present in large numbers: Fragmentation Injury: Microangiopathic haemolysis, haemangiosarcoma, DIC Oxidant Injury: Keratocytes may accompany eccentrocytes & possible Heinz Bodies Liver Disease in cats e.g. hepatic lipidosis

Answer 70

Have irregularly spaced, variably sized spicules usually ending in a "club-shaped" or "fish" Diseases with Increased fragmentation e.g. Heamangiosarcoma, liver disease, DIC, glomerulonephritis

Answer 71

Agents: Distemper, Anaplasma (Centrale, marginale), Babesia, Mycoplasma (Haemofelis, haemocanis), Candidatus Mycoplasma Haemominutum, Theileria Diagnosis: - Presence of Organism: Absence does not rule out presence. Degree of parasitaemia does not necessarily correlate with the degree of clinical disease. - Blood smear: Morph: Spherocytes, agglutination (Due to concurrent immune-mediated components) Sample: Fresh blood to avoid dislodging from membrane, capillary blood smears usually more helpful than jugular or cephalic, buffy coat smears may help conc organism

Answer 72

1. Heparin Induced haemolysis In horses heparin anticoagulant therapy can cause RBC agglutination CS: Hyperbilirubinemia, 6-8hrs post treatment and resolves after 5d 2. Envenomation (snakes) Pathogenesis: - Cobra venom: Activates Complement system - Rattlesnakes: Haemolysins (Phospholipase A2) cause direct haemolysis - Bees: Haemolysins (Phospholipase A2) cause spherocytic haemolytic anaemia

Answer 73

Primary: Blood vessels, platelets, von williebran factor Secondary: Cascade and models produce thrombin which converts fibrinogen to Fibrin. Fibrin stimulates cross-linking between fibrin to form a stable clot Tertiary: Fibrinolysis to cause the breakdown of a clot via plasmin to re-instate blood flow

Answer 74

Sample Collection Tube: Citrate vacuum + Non-hep catheter flushed w/ 5mL saline & discard 6x dead space (5ml) Method: Centrifuge immediately for 10 minutes, collect plasma with pipette --> Place in plain plastic tube. This will be stable at room temperature except for slight decrease in fibrinogen, for 48 hours. Ratio: 1:9 (Citrate to blood). Under filled: there is prolonged times and reduced coagulation as over-citrated Over fill: Reduced times, hyper coagulable as under citrated Avoid: - Heparinized catheters - Excess vacuum (Platelet activation) - Prolonged vessel occlusion - Activation of platelet, coagulation, fibrinolytic activation - Traumatic venipuncture → produces tissue factor → initiates coagulation & affects results - Drawing into dry syringe - Incomplete blood draw - Air in vacutainer (Depletes or dilutes)

Answer 75

Clinical Signs: Petechiae, Ecchymoses, Bleeding post injection, GI bleed/melena, epistaxis, haematuria Components: 1. Vascular: No tests available 2. Platelet Count: - Automated Analyser (EDTA) - Blood smear (EDTA): Not accurate count as platelets are clumps. 100x objective and count 10 points. Normal 10 plt/hpf (100x). If there is less than 3 platelets: Spontaneous haemorrhage (IMT) 3. Platelet Function - Buccal mucosal bleeding time Normal: 1-4m (dog), 1.3m (Cat) Testing primary haemostasis or if vWB < 20% Increased BMBT indicates vascular lesions/capillary fragility OR lack of platelets/platelet defect Method: 5mm cut is made in the upper lip and the time until bleeding ceases & crescend blood no longer forms on filter paper is recorded Increased: Severe thrombocytopenia or anaemia, thrombocytopathy - Clot Retraction Time Method: 2mL blood collected from 2 animals and control into a plain tube. It is left to clot at 37 degrees, after 1 hr clot retraction of the 3 vials is compared Normal: Serum production 30-50% Defective: Thrombocytopenia/pathy, erythrocytosis, hypofirinogenemia Increased: Anaemia DIC: Clot is small & ragged, partially disintegrated via excess plasmin. Disseminated intravascular coagulation vWB Factor: - vWB Factor (Elise/Antigen) Method: Plasma Harvested after blood collection in EDTA or citrate --> Shipped to lab Interpretation: Reported as and relative to pool of healthy species references Free of vWD: Ag >70%, Carriers: 50-69% but not at risk of bleeding Greater than 70% is considered as normal. Dogs with less than 50% are carriers that will transmit to offspring. Risk of clinical von willieburns disease. Dogs that will bleed: <35% There may be false decrease in vWF is the sample has clotted or haemolysed There may be false increases in vWF due to excercise, pregnancy, epinephrine, endotoxin, azotaemia or liver disease. - DNA Test Method: Buccal swab and smear submitted Interpretation: Genetic tests don't always correlate to CS; will tell if clear, carrier or affected

Answer 76

Clinical signs: Bleeding into cavities/joints/muscles/haematomas + GI bleed, hematuria, epistaxis Proenzymes II, VII, IX, X are Vitamin K dependent Coagulation factors IX deficiency (Haemophilia B): Subcutaneous haematoma of head VII Defieciency (Haemophilia A): Haematoma of stifle, perirenal haemotoma. 1. Activated Clotting Time (ACT) Tests: Intrinsic & Common Pathway --> Intrinsic Pathway: Propagation of thrombofibrinogen to fibrin using co-factors XI, VIII, V ACT: Prolonged if: <10% of factors (90% loss) Prolonged test results may be due to: Anticoagulant rodenticide intoxication, Disseminated intravsacular coagulation (DIC) Normal: Dogs - 60-90s, Cats - < 165 s Modified APTT: Tests for severe primary or secondary coagulopathy. < 30% of factors MOA: Depends on platelet phospholipid to support reaction Method: 2mL is added to a diatomaceous earth activator for factor XIII tube and are inverted until a clot forms. 2. APTT Tests: Intrinsic and common pathway Prolonged if: <30% of factors (70% loss) MOA: Depends on adding of a phospholipid in a lab setting Inflammation: Can cause shorter time then expected as fibrinogen, factor V & VIII may increase with inflammation. 3. PT Tests: Extrinsic Indication: K deficiency, influences II, VII, IX, X Prolonged (6-10secds): Factor < 20-25% suggestive of pathology/disease 4. Thrombin Clot Time: Direct measurement of functional fibrinogen & clotting time can be converted to determine fibrinogen concentration Tests: Common Pathway Method: Time for clot formation in citrate + Ca + Thrombin Hyperfibrinogenemia: Acute phase protein that increases with inflammation Hypofibrinogenemia: DIC, synthetic liver failure via inhibitor of thrombin (Heparin) or fibrin polymerisation or paraproteinemia

Answer 77

1. APTT 2. PT 3. FDP: Detects fibrinogenolysis & Fibrinolysis 4. D-Dimer D-dimer presence indicates the generation of thrombin & plasmin that breaks down clot. Marker of hypercoagulability Detects: Thrombin generated for fibrinolysis of cross-linked fibrins and activates FXIII & Plasmin - Physiological causes: Wound healing/post-surgery there is increased in D-Dimer - Pathological: Internal haemorrhage, any cause of thrombosis/thromboembolism (DIC, Sepsis, Neoplasia) False Increase: Sample haemolysis

Answer 78

1. Antithrombin III Decreased: Protein losing nephropathies and enteropathies Chronic hepatitis/Cirrhosis Sepsis Hypercoaguable states Cats: Behave like an acute phase protein and increased with varied conditions 2. Tissue Factor Pathway Inhibitor: Inhibits FX & Thrombin 3. Protein C: Cleaves FVa and FVIIIa

Answer 79

Thrombocytopenia: Platelet destruction/consumption: IMT, DIC Decrease in the production of haemic cell lines in the bone marrow Can be due to: - Chemotherapy - Oestrogen in dogs - Bracken ferm poisoning Can be reduced temporarily if sequestered in the spleen Cattle CS: Petechiae found on the gums, ventral tongue, conjunctival sclera Causes: Acute bracken fern, acute BVDV, trichothecene mycotoxicosism bleeding calf syndrome IMT: Immune mediated thrombocytopenia Platelet destruction common in dogs Thrombocytopathy vWD: The function vWB: Platelet adhesion and Stabilising & Protective Carrier Molecule Cause: Hereditary especially in dogs Type 1: All Multimers present in decreased concentration. With mild-severe bleeding Hosts: Dobermans, Incidence: Most Common Type 2: Disproportionate decrease in large multimers with severe bleeding Uncommon Type 3: All multimers are absent causing severe bleeding CS: Prolonged haemorrhage Pattern of haemorrhage: Absence of petechia. Cutaneous bruises and mucosal bleeds Prolonged BMBT: Normal usually APTT: Prlonged only in horses

Answer 80

1. Hereditary Disorders: CS: Bleeding tends to occur within first year of life Prolonged PT: Factor VII deficiency Prolonged APTT: Factor XII, XI, IX, VIII deficiency Prolonged PT & APTT: Factor X, Factor V, prothrombin, fibrinogen or combined factor deficiency. 2. Acquired Disorders: 1. Vitamin K antagonist: Rait Bait, Mouldy Sweet Clover Direct ingestion or poisoned rodent Pathogenesis: Factor deficiency/Inactivity of 2, 7, 9, 10 Vit K. Synth: Carboxylation by Vit K. Dependent enzyme to allow Ca binding --> Allows phospholipid binding --> Coagulation on area of injury Anticoagulant rodenticites: Hydroxycoumarins: 1st Gen, effect takes 1 week and takes multiple doses Inandiones: Second gen, 4-6 weeks, single dose of toxin or rate that are the poison 2. Vitamin K deficiency: Severe choleostasis disease/GIT Disease 3. Liver DIsease: Coagulation factor decifiency, acute liver disease. CS: Bleeding is uncommon but can occur if it is severe 4. DIC

Answer 81

Cause: Secondary to other disease process - Primary haemostasis: Systemic platelet activation --

Clinical Pathology Flashcards

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