Feline Anaemia

Question 1

Why is anaemia common in cats?

Answer 1

Cats good at masking illness - may be profound before clinical signs noted
Short RBC lifespan, lower RBC mass
Haemoglobin has low affinity for oxygen - may be profound before clinical signs noted

Question 2

What are the clinical signs of anaemia?

Answer 2

Pale (or yellow) MMs
Lethargic, weak
Hyperdynamic pulses
Tachycardia, heart murmur
Tachypnoea
Enlarged lymph nodes and spleen
Pica

Question 3

Describe the PCV of an acute anaemia.

Answer 3

Volume of blood loss equally reduces plasma and RBCs so PCV stays normal

Question 4

Describe the PCV of a chronic anaemia.

Answer 4

Reduced RBC volume, increased plasma volume
So PCV decreases below normal

Question 5

What are the key features of regenerative anaemia?

Answer 5

Reticulocytes >50x10^9/l
Anisocytosis
Polychromasia
Mean cell volume (MCV) increased
Mean cell haemoglobin concentration (MCHC) decreased

Question 6

What are the key features of non-regenerative anaemia?

Answer 6

Reticulocytes <50x10^9/l
Normocytic
Normochromic
MCV normal
MCHC normal

Question 7

Define anisocytosis.

Answer 7

Variation in RBC size

Question 8

Define polychromasia.

Answer 8

Variation in RBC density of colour (haemoglobin)

Question 9

Define hypochromic.

Answer 9

Pale (less haemoglobin per RBC)

Question 10

Define nucleated RBC.

Answer 10

Earlier release from bone marrow

Question 11

Define normocytic, microcytic and macrocytic.

Answer 11

Normocytic = normal size RBS
Microcytic =small RBC
Macrocytic = large RBC

Question 12

Describe punctate reticulocytes.

Answer 12

Reticulocytes = immature RBCs released early into circulation
Occur in reasonable numbers in normal non-anaemic cats and so do not represent active regeneration
Can only be seen with new methylene blue stain

Question 13

What is the best way to establish whether an anaemia is regenerative or not?

Answer 13

Absolute reticulocyte count (x10^9/l) = observed % reticulocytes x RBC count (x10^12/l) x 10

Question 14

Which two confounding factors can make it harder to categorise anaemia?

Answer 14

Duration of anaemia
Concurrent disease e.g. FeLV, cat flu

Question 15

What causes of haemorrhage can lead to a regenerative anaemia?

Answer 15

Trauma
Coagulopathies
Chronic blood loss from flea infestations/infected tumours/GI tract

Question 16

What causes of haemolysis can lead to a regenerative anaemia?

Answer 16

Infection e.g. FeLV
Immune-mediated e.g. drugs, neoplasias, FeLV
Heinz body anaemia e.g. paracetamol/onion toxicity, lymphoma
Severe hypophosphataemia e.g. refeeding syndrome
Incompatible blood transfusions
Neonatal isoerythrolysis

Question 17

What is Feline Infectious Anaemia?

Answer 17

Caused by mycoplasma haemofelis, transmitted by fleas

Question 18

What are the clinical signs of FIA?

Answer 18

Pallor
Lethargy
Anorexia
Weight loss
Pyrexia
Dehydration
Jaundice (if severe acute)

Question 19

How do we diagnose and treat FIA?

Answer 19

PCR for diagnosis
Treated with doxycycline (followed by food/water)

Question 20

Describe non-regenerative anaemia.

Answer 20

Most anaemic cats have non-regenerative anaemia
Bone marrow fails to respond adequately to anaemia and does not produce new RBCs
Bone marrow sampling needed to determine cause of anaemia

Question 21

What can cause a non-regenerative anaemia?

Answer 21

Disorders of the bone marrow (severe!)
Secondary to systemic disease e.g. neoplasia, FeLV, FIV, FIP, bacterial infections, chronic inflammation and chronic kidney disease

Question 22

Describe blood transfusions as a supportive measure for anaemic cats.

Answer 22

Useful adjunct treatment for FIA and non-regenerative anaemias
Based on clinical grounds rather than a specific PCV cut-off (different effects with chronic/acute anaemia)

Question 23

Describe erythropoietin as a treatment for anaemia.

Answer 23

Some success in cats with chronic kidney disease
Not all patients respond and there are a number of side effects
Newer recombinant human treatments are available that have lower development of severe side effects

Question 24

Describe bone marrow stimulation as a treatment of anaemia.

Answer 24

Anabolic steroids sometimes used in first line treatment
May stimulate erythroid precursors in bone marrow
Prednisolone may be considered on the basis that an immune-mediated mechanism has been proposed in some cases of marrow failure
Can improve QOL and appetite of CKD cats