Equine Neonatal Disease

Question 1

When does a foal develop lymphocytes?
What about immunoglobulins?

Answer 1

T lymphocytes- 100 days of gestation
B lymphocytes- 200 days of gestation

Immunoglobulins- do not receive until AFTER birth- in colostrum

Question 2

Maternal antibodies suppress…

Answer 2

production of the foals own IgG

Question 3

When does Ig in serum reach its peak in foals after adequate colostrum ingestion?

Answer 3

peaks at 18-24 hours
[measurable from 4-6 hours]

Question 4

How does a foal integrate the maternal Ig into its own immune system?

Answer 4

Specialised enterocytes allow absorption of Ig via pinocytosis so they can be internalised without digestion

Question 5

When is the foals lowest level of Ig absorption?
When does the Ig reach adult levels?

Answer 5

Nadir= 1-2 months of age
Adult levels reached at 5-10 months

Question 6

What maternal factors can contribute to failure of passive transfer?

Answer 6

Lack of colostrum/ premature lactation
Poor quality colostrum- low Ig conc

Question 7

What foal related factors can contribute to failure of passive transfer?

Answer 7

Lack of colostrum intake e.g. inability to nurse or foal rejected by mare
Lack of colostrum absorption- ingested too late or GIT disease

Question 8

What affects the amount of IgG that the foal requires?

Answer 8

Farm management
Environmental factors

Question 9

What Ig level indicates a failure of passive transfer and what indicates a successful transfer?

Answer 9

FAILURE- less than 400mg/dL
Success- more than 800mg/DL

[snap test figures]

Question 10

How can we treat FPT and when are these indicated? (2)

Answer 10

Colostrum via nasogastric tube if foal is less than 12 hours old
Intravenous plasma- if foal is older than 12 hours and showing signs of systemic disease

Question 11

What are the advantages and disadvantages of using Plasma?

Answer 11

Easy to use and commercially available
BUT contains no antibodies against local disease and foal may needs several litres if its already fighting an ongoing infection

Question 12

How do we administer plasma in a foal with FPT?

Answer 12

1 drop per second/ 3ml a min
If no reaction after after 15 mins can speed up administration

Question 13

What is Neonatal Isoerythrolysis and what is it caused by?

Answer 13

Immune mediated haemolytic anaemia of newborn foals
Caused by incompatibility between mares and foals blood group causing the mare to produce antibodies against the foals RBC antigens

Question 14

Under what two mechanisms can Neonatal Isoerythrolysis occur?

Answer 14

1. Foal inherits Sire’s RBC antigens- mare exposed to them via transplacental haemorrhage, parturition etc.
   OR 2. Foal inherits Sire’s RBC antigen- mare already has built antibodies against them and are in the colostrum

Question 15

When would we expect to see clinical signs of Neonatal Isoerythrolysis and what would these be?

Answer 15

CS develop 1-12 days of age (usually 3 on average)
Signs include- weakness, increased HR, increased respiratory rate, icterus

Question 16

How do we diagnose Neonatal Isoerythrolysis?

Answer 16

Haemolytic cross match- identify haemolysis of foals RBC’s by mares serum

Question 17

What is requires for a Haemolytic Cross Match test?

Answer 17

An external complement- usually Rabbit

Question 18

How do we treat Neonatal Isoerythrolysis? (3)

Answer 18

Prevent further colostrum intake e.g. muzzle foal
Supportive care- IV fluids if severely haemoglobinuric
Blood transfusion with WASHED RBC’s from the mare (not the plasma!- no Ig)

Question 19

How can we prevent Neonatal Isoerythrolysis? (2)

Answer 19

Determine blood group of Sire to ensure it matches Mares before breeding
Test serum for the alloantibodies

Question 20

What is type of genetic disease is Combined Immunodeficiency and what group does it affect?

Answer 20

Autosomal recessive genetic disease
Arabian foals

Question 21

What is Combined Immunodeficieny?

Answer 21

Enzymatic defect that causes no mature functional T or B cells so foal suffers recurrent infections

Question 22

Why do Equines not show signs of anaemia despite suffering with it for ages?

Answer 22

They have a large splenic reserve and their erythrocyte lifespan is 140-150 days (long!)

Question 23

In domestic species we can categorise Anaemia as regenerative/ non regenerative based on a blood sample- why can’t we do this in Horses?
What is the alternative?

Answer 23

They have no circulating Reticulocytes- have to use bone marrow instead

Question 24

What laboratory signs will indicate a Horse has anaemia?

Answer 24

Increases plasma lactate concentration due to inadequate oxygen delivery to tissues
Decreased venous blood oxygen levels as all available oxygen is going into the tissues where it is needed more

Question 25

In relation to Equine Anaemia, what is a major cause of death post partum?

Answer 25

Periparturient Haemorrhage- haemorrhage from uterine vessels and reproductive tract during birth

Question 26

What makes the difference between Periparturient Haemorrhage being fatal and non-fatal?

Answer 26

Broad ligament in tact- blocks and contains the blood
If this doesn’t happen then the blood leaks in to abdomen and is rapidly fatal

Question 27

How does a horse get Equine Infectious Anaemia?

Answer 27

It’s a Lentivirus- transmitted via insects or blood contaminated equipment

Question 28

How do we diagnose Equine Infectious Anaemia?

Answer 28

Coggin’s Test or ELISA

Question 29

How do we treat Horses with Equine Infectious Anaemia?

Answer 29

Euthanasia or lifelong quarantine

Question 30

Apart from infections and immune mediated anaemia, how else may a Horse acquire Haemolytic Anaemia?

Answer 30

Drugs e.g. Phenothiazinr caused Heinz Body Formation
Red Maple Leaf Toxicity causes oxidative change of Hb