Equine anaemia

Question 1

What are the causes of external blood loss in horses?

Answer 1

External wound involving large artery
Guttural pouch mycoses
Post surgical haemorrhage - castration
Into GI lumen
Haematuria - uncommon in horses

Question 2

What are the cavities that blood can bleed into in horses?

Answer 2

Peritoneal, thoracic and urogenital

Question 3

What are the causes of haemoperitoneum?

Answer 3

Spleen or liver rupture, mesneteric vessel rupture, uterine artery rupture, neoplasm, internal bleeding following castration, Erosion of a large vessel by abscess or neoplasm or rupture of aneurysm, Coagulopathy

Question 4

What are the causes of haemothorax?

Answer 4

Secondary to a traumatic event, Erosion of a large vessle by abscess/neoplasm or aneurysm rupture, Rupture of aorta/pulmonary vessel, Coagulopathy, Neoplasia

Question 5

What are the causes of blood loss via urogenital tract?

Answer 5

Uterine artery rupture before/after parturition

Question 6

What are the causes of immune-mediated haemolytic anaemia (IMHA) in horses?

Answer 6

Primary - uncommon autoimmune process
Secondary due to alterations in RBC membrane by primary infections/neoplasia/other immune-mediated disease process, antigen-antibody complex deposition on surface of RBCs or drugs that cause immunoproteins to react indirectly with RBCs

Question 7

What is the treatment for IMHA in horses?

Answer 7

Discontinue all treatments if possible, treat primary condition, blood transfusion if necessary, immunosuppression if necessary using corticosteroids

Question 8

What are Heinz bodies?

Answer 8

Precipitations of oxidatively denatured haemoglobin

Question 9

What causes Heinz bodies in horses?

Answer 9

Rarely used drugs (methylen blue, phenothiazine) or plants horses rarely consume in sufficient concentrations (onions, Brassicas), Red Maple Leaf Toxicity in USA

Question 10

What is Equine Infectious Anaemia (EIA)?

Answer 10

Exotic to the UK and is caused by Equine Infectious Anaemia virus which is a lentivirus and causes a persistent infection with no treatment

Question 11

What are the characteristics of anaemia due to chronic disease?

Answer 11

Most common cause of anaemia in adult horses, mild-moderate non-regenerative anaemia, not severe enough to cause clinical signs

Question 12

What is the pathogenesis of anaemia due to chronic disease?

Answer 12

Iron sequestration, defective erythropoietin response, decreased RBC life span

Question 13

What is the treatment for anaemia due to chronic disease?

Answer 13

Treat the primary disease

Question 14

What is the cause and treatment of Iron Deficiency Anaemia?

Answer 14

Chronic external blood loss

Oral iron supplementation

Question 15

How developed is the neonatal foal immune system?

Answer 15

Capable of mounting an immune response but no antigenic memory so relies on ingestion of colostrum to allow time for foal to start to produce its own antibodies

Question 16

What is the composition of colostrum?

Answer 16

Mainly IgG, some IgA and IgM

Question 17

How is the Ig absorbed from the colostrum?

Answer 17

Foals suckle withing 1-3 hours after birth and consume 1-2L and specialised enterocytes allow absorption of large IgG molecules with maximal capacity at 6 hours

Question 18

What is the consequence of failure of passive transfer in horse?

Answer 18

Predisposes foal to infectious disease especially bacteraemia/sepsis, septic arthritis, diarrhoea and pneumonia

Question 19

What can cause failure of passive transfer in foals?

Answer 19

Lack of colostrum/poor quality colostrum (premature)
Failure of foal to nurse (PAS, orthopaedic problem, mare temperament)
Failure of absorption as GIT of foal unable to absorb colostrum

Question 20

How is failure of passive transfer in foals diagnosed?

Answer 20

Measurement of IgG concentrations

<4g/l = FPT, 4-8g/l = partial FPT,

Question 21

What is the treatment for failure of passive transfer in a foal?

Answer 21

Less than 12-18 hours = oral colostrum
>12-18 hours = IV plasma, 1L will increase IgG conc by 2g/l
Treat underlying disease (antibiotics for infections)

Question 22

What is neonatal isoerythrolysis?

Answer 22

Haemolytic disease of foals caused by destruction of foals RBCs by antibodies present in colostrum

Question 23

What causes neonatal isoerythrolysis?

Answer 23

Blood group incompatibility of mare and foal in multiparous mares that have been sensitised to foals RBC antigens during pregnancy

Question 24

What is the sequence of events causing neonatal isoerythrolysis?

Answer 24

Foal inherits RBC antigen from sire that is different to mare, antigen must be strongly antigenic (Aa,Qa)
Mare must be exposed to RBC antigen and produce antibodies to it and are contained in mare’s colostrum
Foal ingests colostrum, antibody-coated RBC removed from circulation or lysed intravascularly

Question 25

What are the clinical signs of neonatal isoerythrolysis?

Answer 25

Normal at birth, develop signs withing 1st 4 days of life
Weakness, lethargy, increased HR and RR, icterus, pale MM
Time of onset and severity dependent on amount of antibodies ingested and affinity of antibodies to RBC

Question 26

How is neonatal isoerythrolysis diagnosed?

Answer 26

Clinical signs, haemolytic cross match, thrombocytopaemia may accompany anaemia

Question 27

How can neonatal isoerythrolysis be prevented?

Answer 27

Check for antibodies in late gestation

Prevent foal from nursing in first 24-48hours and provide alternative colostrum

Question 28

What is severe combined immunodeficiency?

Answer 28

Affects Arab foals, autosomal recessive
Lack of functional T and B lymphocytes
Can test for SCID gene