Clinical Haematology 2

Question 1

1. Define anaemia.
2. Define erythrocytosis.
   – Define relative erythrocytosis.
   – Define absolute erythrocytosis.

Answer 1

1. Decrease in red blood cell mass as determined by decrease in erythrocyte concentration in blood as measured by reduced RBC, Hb, HCT, PCV.
2. Increase in concentration of erythrocytes in blood as measured by increased RBC, Hb, HCT, PCV.
   – Relative = resulting from reduced blood volume (dehydration) i.e. haemoconcentration.
   – Absolute = Polycythaemia (increased RBC mass) –> resulting from a genuine increase in red cell mass. LESS COMMON.

Question 2

Why is anaemia clinically relevant?

Answer 2

Brings about a reduced oxygen carrying capacity.
Brings about a reduced oxygen delivery to the tissues – unable to metabolise properly, with some going into aerobic respiration and others failing.
Identified in the kidneys which produce erythropoietin, stimulating production of more RBCs to bring oxygen carrying capacity and oxygen delivery back up to normal.

Question 3

What is the clinical presentation of anaemia dependent on?

Answer 3

• Severity.
• Chronicity of development.
• Clinical spectrum – subclinical > non-specific lethargy > exercise intolerance > overt collapse / tachypnoea > death.

Question 4

1. Acute anaemia clinical presentation.
2. Chronic anaemia clinical presentation.

Answer 4

1. e.g. Haemolytic.
   PCV 18%.
   Tachycardia, tachypnoea, haemic murmur, weak, barely ambulatory.
2. e.g. bone marrow disease.
   PCV 14%.
   Exercise intolerant and lethargic at home, but walked into consult, interactive, still looking for food.
   Note: pica – ingestion of inappropriate products e.g. licking concrete, licking walls, eating soil – relates to their desire to try and get hold of iron sources.

Question 5

What is anaemia generally subdivided into?

Answer 5

Regenerative and non-regenerative.

Question 6

1. What is regenerative subdivided into?
2. What is non-regenerative subdivided into?
3. How long is the pre-regenerative phase and what is this?

Answer 6

1. Haemolysis and haemorrhage.
2. Extra-bone marrow disease and primary bone marrow disease. Typically kidney suppressing bone marrow or not producing enough EPO to signal bone marrow production.
3. 3-5 days. The period of time where a haemorrhage or haemolysis has occurred and the bone marrow has not yet reacted to this to produce more RBCs.

Question 7

What can be seen in the increased demand for RBC production?

Answer 7

Reticulocytosis = regeneration.
Reticulocytes are larger and bluer than mature RBCs and are premature and kicked out early in order meet demands.

Question 8

What are aggregate reticulocytes?

Answer 8

More immature reticulocytes which retain large amounts of ‘aggregates’ of RNA – appear purple when stained. Appear as aggregates when stained with
Mature within 1-2 days in circulation.
Appear as polychromatophils when stained w/ routinely used Rowanowsky-stains (e.g. Wright’s, Giemsa, Diff-Quik etc.

Question 9

What are punctate reticulocytes?

Answer 9

Mature – retain only small ‘punctates’ or RNA.
Visualisation requires staining w/ intravital dyes.
Only present in cats (not dogs).
– may persist for a few weeks in circulation.

Question 10

1. What is the most regenerative measure of regeneration in dogs and cats?
2. What is the case for horses?
3. What is the case for cattle/sheep?

Answer 10

1. Reticulocyte count.
2. Horses retain reticulocytes un the bine marrow and they are not seen in the circulation.
3. Cattle/sheep have variable release of reticulocytes, often only see them w/ severe anaemia.

Question 11

What are other morphological features of regeneration?

Answer 11

Polychromasia (abnormally high number of immature RBCs found in bloodstream due to premature release from bone marrow during blood formation).
Anisocytosis (abnormal variation in size of RBCs).
Nucleated RBCs.
– Other RBC precursors.

Question 12

1. Define normocytic, macrocytic, microcytic respectively.
2. Define normochromic, hypochromic, hyperchromic respectively.

Answer 12

1. Nirmal mean cell volume, high mean cell volume, low mean cell volume.
2. normal mean cell haemoglobin / mean cell haemoglobin concentration, low mean cell haemoglobin / mean cell haemoglobin concentration, high mean cell haemoglobin / mean cell haemoglobin concentration (not possible – artefact due to haemolysis / lipaemia / Heinz bodies).

Question 13

What happens during erythropoiesis?

Answer 13

RBC become progressively smaller / accumulates Hb.
Hb reaches threshold and nucleus is extruded, cell changes from nucleated RBC to reticulocyte.
If Hb levels continue to decrease, ongoing cell divisions, increasing the time for Hb to accumulate and microcytic cells.
Extreme: inadequate Hb causes hypochromic RBC, iron deficiency with microcytic cells and sometime hypochromic anaemia.

Question 14

1. What happens to RBCs in extravascular haemolysis?
2. What happens to RBCs in intravascular haemolysis?
3. Which is deemed to be worse?

Answer 14

1. phagocytosed primarily in the spleen.
2. lyse in circulation due to membrane damage.
3. Intravascular due to the degree of damage caused by Hb in circulation at this level.

Question 15

1. What are the clues for haemolysis?

Answer 15

1. Haemoglobinaemia (can become haemoglobinuria).
   Bilirubinaemia (clinical jaundice / bilirubinaemia).
   Ghost cells (remnants of membrane where they have ruptured and release Hb into circulation).
   Other RBC morphological changes (Heinz bodies).
   If immune-mediated, may have:
   - Spherocytes (membrane removed so SA reduced but volume maintained so biconcave lost).
   - Autoagglutination (in saline agglutination).
   - Positive Coomb’s / Direct Antibody Test (DAT).

Question 16

Differentials for haemolysis.

Answer 16

• Primary IMHA.
• Infectious agents – haemotropic mycoplasma (mycoplasma haemofelis), babesia canis, FeLV, equine infectious anaemia virus.
• Oxidative damage (Heinz bodies, eccentrocytes).
  – Toxins: Allium spp. (garlic etc), paracetamol, zinc, brassicas e.g. cabbage, sprouts (ruminants), red maple leaf (horses).
  – Systemic disease.
• Hypophosphataemia.
• Neonatal isoerythrolysis.
• Transfusion reactions.
• Microangiopathic disease (shear injury).
• Hereditary RBC enzymopathies (PFK / PK deficiency).
  -Other rare causes – envenomation, erythrophagocytic disease.

Question 17

1. What is primary IMHA?
2. What is secondary IMHA?

Answer 17

1. Autoimmune.
2. Secondary to molecular mimicry, haptenisation etc.
   – Can be triggered by neoplastic or inflammatory / infectious disease, anywhere in the body (e.g. UTIs).
   – Can be triggered by recent drug use.
   –> penicillins, cephalosporins, trimethoprim-sulphonamides.
   – RBC-associated infection disease w/ variable mechanisms of inducing haemolysis.
   –> Intra-cellular parasites.
   –> Extra-cellular parasites.

Question 18

Difference between agglutination and rouleaux formation?

Answer 18

Agglutination is where the RBCs randomly stick together.
Rouleaux formation is where the RBCs stack themselves quite orderly in a line.
– more commonly seen in animals w/ high globulin levels.
– NOT autoagglutination (where ABs stick to red cells.

Question 19

1. What does Coomb’s testing evaluate?
2. In what cases is Coomb’s testing pointless and why?
3. Sensitivity / specificity? – how is this combatted?
4. Coomb’s reagent?
5. Coomb’s testing technique?

Answer 19

1. For presence of antibody and/or complement on RBC surface.
2. Clinically pointless if in saline autoagglutination present as we know it will be positive.
3. Far from perfect w/ false positives and false negatives – interpret result in light of the patient.
4. Species-specific antibody directed against IgG, IgM, or complement.
5. Patient’s RBCs are washed and mixed w/ serial dilutions of Coombs’ reagent (at 4C and 37C).
   The highest dilution at which agglutination occurs is reported.

Question 20

Clinical approach to IMHA.

Answer 20

Confirm diagnosis.
- Regenerative anaemia w/ evidence of haemolysis.
- AND spherocytes (evidence of attack of RBC surface) and/or autoagglutination or Coombs’ positive.
History.
- Recent drug administration?
- Travel?
Screen for systemic neoplastic / inflammatory / infectious disease.
- Thoracic radiographs.
- Abdominal ultrasound.
- ECG (w/ suspicion of endocarditis).
- Culture / PCRs (Babesia spp., haemotropic mycoplasmas esp. in cats) / serology.

Question 21

Neonatal isoerythrolysis in cats.

Answer 21

Naturally occurring, clinically significant, alloantibodies.
Typically type B mum w/ type A kittens.
Colostrum – type B mum always has strong anti-A antibodies in plasma – secreted into colostrum. Typically where type A tom cat and type B queen have mated.
Erythrocyte surface antigens are genetically-mediated.
Haemolysis occurs when type A or AB kittens ingest colostrum from type B queen (i.e. containing anti-A antibodies).
Haemolysis and associated signs (jaundice etc.) occur within hours to days of ingestion.
Prevent by managed mating (blood-typing queen/tom) or blood typing kittens prior to first feed.

Question 22

1. What types of internal haemorrhages are there?
2. What type of external haemorrhages are there?
3. What is melena?

Answer 22

1. Haemothorax, haemoabdomen.
2. Body surface (clearly visible).
   From external surfaces (hidden) – often associated with GIT, genitourinary tract, respiratory tract.
3. Digested / changed faeces that is passed in the faeces, making it appear dark and sticky.

Question 23

What to consider when dealing with haemorrhage.

Answer 23

Is it global?
- Bleeding diathesis (coagulopathy, thrombocytopenia, fibrinolysis).
Primary pathology at the site of haemorrhage.
- Trauma.
- Neoplasia.
- Inflammation (e.g. ulcer).
- Idiopathic.

Question 24

Causes of body cavity haemorrhage.

Answer 24

Secondary haemostatic disorder i.e. coagulopathy.
- Lack of clotting factors.
– Acquired e.g. rodenticide intoxication, angiostrongylosis, liver disease.
– Congenital e.g. haemophilia.
Primary pathology within the body cavity.
- Traumatic.
- Non-traumatic.
– Abdominal –> splenic&raquo_space; hepatic (» renal, adrenal, other). Ryptured splenic malignancy most common.
– Thoracic (less common than abdominal).
–> Thymic involution (adolescent) (benign) vs neoplasia.

Question 25

How to identify external haemorrhage of GI tract.

Answer 25

• If overtly apparent, haematemesis / haematochezia / melaena.
  – Thorough CE incl. consideration for swallowed blood (oral, nasal, pulmonary).
• If occult,
  – regenerative anaemia without alternative explanation.
  –> progresses to iron deficiency (poorly / non-regenerative microcytic / hypochromic).
  –> GI blood loss is the MOST COMMON cause of iron deficiency anaemia.
• May also see increased urea (non-fasted as had a blood protein meal), thrombocytosis, occasional spherocytes.

Question 26

1. What is serum iron expected to be with iron deficiency anaemia?
2. What is total iron binding capacity expected to be with iron deficiency anaemia?
3. What is expected of the total % transferrin saturation with iron deficiency anaemia?
4. What is expected of the bone marrow iron stores with iron deficiency anaemia?

Answer 26

1. Low.
2. Normal/high.
3. Low.
4. Low.

Question 27

1. What is expected of the serum iron levels with anaemia of chronic disease?
2. What is expected of total iron binding capacity with anaemia of chronic disease?
3. What is expected of % transferrin saturation with anaemia of chronic disease?
4. What is expected of bone marrow iron stores with anaemia of chronic disease?

Answer 27

1. Low.
2. Low.
3. High.
4. High.

Question 28

GIT haemorrhage differentials.

Answer 28

• Haemostatic disorder – primary disorder (thrombocytopenia) most common.
• Primary pathology e.g. ulceration.
  –Drug-related e.g. NSAIDs, steroids.
  – Addison’s disease.
  – Foreign body.
  – Neoplasia – esp. gastric carcinoma.
  – Secondary to hyperhistaminaemia (mast cell tumour; cutaneous&raquo_space; elsewhere).
• e.g. parasitism (e.g. hookworms).
• e.g. inflammatory bowel disease.

Question 29

Identifying external haemorrhage.

Answer 29

Body surface (or SC) would be obvious.
- Flea infestations important in young/small animals.
Urinary tract – macroscopic pigmenturia.
- Confirm haematuria (rather than haemoglobinuria).
- Primary pathology – UT tumours, idiopathic renal haematuria.
Respiratory tract – usually clinically obvious.
- Angiostrongylus vasorum MOST IMPORTANT (pathology and/or coagulopathy).
- Rodenticide intoxication.
- Primary pathology e.g. pulmonary tumours (uncommon).
- Thrombocytopenia.
Reproductive tract – rare post-partum complication.

Question 30

1. What will the smear exam look like in the case of non-regenerative anaemias?
2. Why may the blood be rechecked a few days later?
3. What are the exceptions?

Answer 30

1. Normocytic, normochromic, red cell indices (MCV, MHC/C) will be normal.
2. May be in a pre-regenerative phase.
3. • Iron deficiency – microcytic +/- hypochromic.
     – chronic GI blood loss.
     - Macrocytic non-regenerative anaemia in cats associated with FeLV infection.

Question 31

Causes of extra-bone marrow disease.

Answer 31

Chronic GI blood loss.
Any chronic disease (common examples indicated).
Oestrogen producing tumour.
Chemotherapeutic drugs.

Question 32

1. What do we see in haematology with chronic GI blood loss?
2. What are common chronic diseases that may result in extra-bone marrow disease?

Answer 32

1. Microcytic +/- hypochromic.
2. CKD.
   Endocrinopathies (hypothyroidism, hypoadrenocorticism).
   Chronic inflammatory disease.
   Neoplasia.

Question 33

1. Causes of primary bone marrow disease.

Answer 33

1. infiltrative disease e.g. leukaemia, stage V lymphoma, multiple myeloma.
   Infectious – FeLV, parvovirus.
   Non-regenerative IMHA (either primary (autoimmune) or secondary).
   Myelofibrosis (bone marrow being replaced with fibrous fatty tissue).

Question 34

Investigating normocytic normochromic non-regenerative anaemias.

Answer 34

Extra marrow disease will rarely cause severe anaemia.
Ensure truly non-regenerative (repeat haematology in 3-5 days if necessary).
Is there evidence of neoplastic / inflammatory / metabolic disease?
- Biochem / urinalysis – evidence of kidney disease.
- Test for hypothyroidism / hypoadrenocorticism (dogs).
- Test for FeLV (and sometime FIV) (cats).
- Screening (imaging) for unidentified neoplastic / inflammatory disease.
- Travel screen if indicated.
Once all above excluded, bone marrow biopsy.
- If bicytopenic / pancytopenic, suspicion of bone marrow disease increases.

Question 35

1. What is erythrocytosis?
2. What must we consider before we worry about this?
3. What forms of erythrocytosis can be seen?

Answer 35

1. Increased red cell mass.
2. Is it normal for the breed? – site hounds can be much higher as their normal – 65% so 40% probably anaemic for them. Can also be normally higher in brachycephalic dogs too.
3. Relative vs absolute.
   – Relative (haemoconcentration) should NOT push PCV above 65% in dogs and 60% in cats.
   –> typically see a concurrent increase in total proteins (need to know what this is to start off with).
   –> Acute haemorrhagic diarrhoea syndrome is an exception – can sometime be pushed to 75%.

Question 36

Can a mild absolute erythrocytosis (polycythaemia) be normal?

Answer 36

Yes.
In certain breeds.
Can be seen in dogs following a splenic contraction e.g. fear event.
Some systemic disease (rare examples).
- Hyperadrenocorticism.
- Hyperthyroidism.

Question 37

What is the clinical presentation of erythrocytosis?

Answer 37

Increased red cell mass increases blood viscosity – PCV 70%.
Clinical sigs related to impedence of blood flow through capillaries:
- Hyperaemic (darker) MMs +/- cyanosis.
- Blood sludges – spontaneous thrombosis.
- Local hypoxia – tachycardia, tachypnoea, lethargy, exercise intolerance, syncope.
– brain, eyes, kidneys, heart particularly susceptible.
– +/- specific signs relating to organs.
- +/- Epistaxis.

Question 38

What can absolute erythrocytosis be subdivided into?

Answer 38

Erythropoietin dependent and erythropoietin independent.

Question 39

What can EPO dependent absolute erythrocytosis be subdivided into?

Answer 39

appropriate and inappropriate.

Question 40

1. What are causes of appropriate EPO dependent absolute erythrocytosis?
2. What are causes of inappropriate EPO dependent absolute erythrocytosis?
3. What causes EPO independent absolute erythrocytosis.

Answer 40

1. Altitude.
   Right-left cardiac shunt.
   Chronic upper airway obstruction.
   Severe pulmonary disease
2. Paraneoplastic EPO production e.g. renal carcinoma (most likely) or other.
3. Primary polycythaemia vera.

Question 41

1. What would be seen on CE if a patient has polycythaemia?
2. What may be required before investigation?
3. Evaluate for hypoxia using what measuring methods?
   – What should be done if patient found to be hypoxic?
   — what if they are not hypoxic?
4. What measurement could be taken?

Answer 41

1. Cyanosis / differential cyanosis – make sure cyanosis, not methaemoglobinaemia.
2. Therapeutic phlebotomy – 10ml/kg in cats, 20ml/kg in dogs, +/- simultaneous fluids until PCV <60%.
3. SpO2 and arterial blood gas.
   – Carry out a cardiopulmonary investigation.
   –> Barachyceohalic / chronic upper respiratory obstruction.
   –> Echocardiography to determine right-to-left shunt and possible locations of murmurs.
   –> Thoracic imaging +/- further diagnostics.
   — Still carry out imaging for neoplasia – renal, adrenal, other.
4. Measure EPO.