Equine Anaemia

Question 1

Equine specific facts:

1. What is the splenic reserve like?
2. How fast do horses respond to anaemic insult?
3. How can you distinguish regenerative from non-regenerative anaemia?
4. Are Howell-Jolly bodies normal?

Answer 1

1. Large
2. Slow - PCV doesn’t come up quickly
3. No release of reticulocytes into circulation, need bone marrow aspirate
4. Normal

Question 2

What are the clinical and laboratory signs of equine anaemia?

Answer 2

Anaerobic metabolism in tissues
- Increased plasma lactate conc

Increased oxygen extraction from blood
- Decreased PO2 in venous blood

Pale MMs

Increased HR and RR

Weakness, exercise intolerance, collapse

Question 3

What are the acute causes of anaemia in horses?

Answer 3

1. External bleeding
2. Internal bleeding
   - Haemabdomen
   - Haemothorax
   - Broad ligament/urogential tract
   - Kidneys
   - DIC

Question 4

What are the chronic causes of regenerative anaemia in horses?

Answer 4

1. Haemorrhage
   - GI
   - Renal
2. Haemolysis
   - IM
   - Infectious
   - Toxic

Question 5

What are the chronic causes of non-regenerative anaemia in horses?

Answer 5

Iron deficiency (rare)
Chronic disease
Bone marrow suppresion

Question 6

What are the causes of a haemabdomen in horses?

Answer 6

Trauma (ruptured spleen/liver)
Ruptured mesenteric vessel
Uterine artery rupture 
Neoplasia
Coagulopathy/DIC
Abdominal abscess

Question 7

What are the causes of a haemothorax in horses?

Answer 7

Trauma
Pulmonary haemorrhage
Necrotising pneumonia
Ruptured pulmonary vessel
Ruptured pulmonary abscess
Coagulopathy/DIC
Neoplasia

Question 8

What are the causes for epistaxis in horses?

Answer 8

Trauma
Ethmoid haematoma
EIPH
Neoplasia
Guttural pouch mycosis
Pulmonary haemorrhage
Coagulopathy/DIC

Question 9

What are the causes of haematuria in horses?

Answer 9

Trauma
Pyelonephritis 
Cystitis
Urolithiasis
Idiopathic
Urethral rent (male)
Neoplasia
Coagulopathy/DIC

Question 10

Causes of GI bleeding in horses?

Answer 10

Parasitism
Neoplasia
Coagulopathy
Ulceration
Granulomatous enteritis 
DIC

Question 11

Causes of haemolysis in horses?

Answer 11

Infectious (EIA)
Immune-mediated
Toxic (Red maple leaf)
Iatrogenic

Question 12

What is the treatment for anaemia in horses?

Answer 12

Guided by clinical and lab findings not PCV
If blood loss located attempt to control
IV fluids if severe acute blood loss
Anaemia itself may not need to be treated if animal is stabilised

Question 13

Haemabdomen in horses

1. Clinical signs
2. Diagnosis
3. Outcome

Answer 13

1. CS:
   - Colic
   - Abdominal pain
   - Hypovolaemia (HR inc, slow CRT/jug fill)
2. Diagnosis: US
3. Good prognosis with trauma, poor with neoplasia => 50% survival

Question 14

How can anaemia be caused by parturition in horses?

Answer 14

Haemorrhage from uterine vessels after parturition
Delivery often uneventful
Bleeding either confined to broad ligament or into abdomen
Tx aimed at CVS stabilisation
Mares prone to repeated bleeding during subsequent pregnancies

Question 15

Is IMHA mostly primary or secondary in horses?

Answer 15

Secondary most often
Antibody formation precipitated by primary disease, drug administration (penicillin and bute), neoplasia, immune-mediated disease

Question 16

How is IMHA diagnosed in the horse?

Answer 16

Coomb’s test
- Demonstrates presence of anti-RBC antibodies on surface of RBC or in serum

Flow cytometry
- Demonstrates antibodies on RBC

Question 17

How is IMHA treated in equids?

Answer 17

Treat primary disease
Stop all medication
Blood transfusion is required
Immunosuppresion
- Steroids 
- Axothioprine

Question 18

What kind of virus is equine infectious anaemia? How is it transmitted?

Answer 18

Lentivirus
Via insects, blood contaminated equipment
Not in the UK but risk from imports

Question 19

Syndromes of equine infectious anaemia…

Answer 19

Acute, chronic, inapparent
Anaemia can be caused by extra/intravascular haemolysis
Bone marrow suppression
Thrombocytopenia

Question 20

How is EIA diagnosed and treated?

Answer 20

Coggin’s test
ELISA
Euthanasia or life-long quarantine => once infected, infected for life

Question 21

What is a sign of oxidative damage to RBCs? What causes it in horses?

Answer 21

Heinz bodies formation

Drugs, plants e.g. red maple

Question 22

Outline the pathophysiology of red maple leaf toxicity…

Answer 22

1. Ingestion of red maple leaves
2. Oxidative changes of Hb Fe2+ to Fe3+
3. Heinz body formation
4. Hb denatured so can no longer carry O2

Question 23

What is the most common cause of anaemia in adult horses?

Answer 23

Anaemia of chronic disease

• Chronic inflammation/infection
• Neoplasia
• Sequestration of iron
• Shortened RBC lifespan
• Defective erythropoietin response

Question 24

What are the clinical signs and treatment of anaemia of chronic disease in horses?

Answer 24

Clinical signs:

• Mild to moderate anaemia
• Normocytic, normochromic
• Non-regenerative
• Not associated with clinical signs

Treatment for primary disease!

Question 25

Describe iron deficiency anaemia in horses…

Answer 25

Can develop with chronic blood loss i.e. parasites
Rare
Treatment with oral iron supplementation