Equine Neonatal Disease Flashcards
When does a foal develop lymphocytes?
What about immunoglobulins?
T lymphocytes- 100 days of gestation
B lymphocytes- 200 days of gestation
Immunoglobulins- do not receive until AFTER birth- in colostrum
Maternal antibodies suppress…
production of the foals own IgG
When does Ig in serum reach its peak in foals after adequate colostrum ingestion?
peaks at 18-24 hours
[measurable from 4-6 hours]
How does a foal integrate the maternal Ig into its own immune system?
Specialised enterocytes allow absorption of Ig via pinocytosis so they can be internalised without digestion
When is the foals lowest level of Ig absorption?
When does the Ig reach adult levels?
Nadir= 1-2 months of age
Adult levels reached at 5-10 months
What maternal factors can contribute to failure of passive transfer?
Lack of colostrum/ premature lactation
Poor quality colostrum- low Ig conc
What foal related factors can contribute to failure of passive transfer?
Lack of colostrum intake e.g. inability to nurse or foal rejected by mare
Lack of colostrum absorption- ingested too late or GIT disease
What affects the amount of IgG that the foal requires?
Farm management
Environmental factors
What Ig level indicates a failure of passive transfer and what indicates a successful transfer?
FAILURE- less than 400mg/dL
Success- more than 800mg/DL
[snap test figures]
How can we treat FPT and when are these indicated? (2)
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
What are the advantages and disadvantages of using Plasma?
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
How do we administer plasma in a foal with FPT?
1 drop per second/ 3ml a min
If no reaction after after 15 mins can speed up administration
What is Neonatal Isoerythrolysis and what is it caused by?
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
Under what two mechanisms can Neonatal Isoerythrolysis occur?
- 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
When would we expect to see clinical signs of Neonatal Isoerythrolysis and what would these be?
CS develop 1-12 days of age (usually 3 on average)
Signs include- weakness, increased HR, increased respiratory rate, icterus
How do we diagnose Neonatal Isoerythrolysis?
Haemolytic cross match- identify haemolysis of foals RBC’s by mares serum
What is requires for a Haemolytic Cross Match test?
An external complement- usually Rabbit
How do we treat Neonatal Isoerythrolysis? (3)
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)
How can we prevent Neonatal Isoerythrolysis? (2)
Determine blood group of Sire to ensure it matches Mares before breeding
Test serum for the alloantibodies
What is type of genetic disease is Combined Immunodeficiency and what group does it affect?
Autosomal recessive genetic disease
Arabian foals
What is Combined Immunodeficieny?
Enzymatic defect that causes no mature functional T or B cells so foal suffers recurrent infections
Why do Equines not show signs of anaemia despite suffering with it for ages?
They have a large splenic reserve and their erythrocyte lifespan is 140-150 days (long!)
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?
They have no circulating Reticulocytes- have to use bone marrow instead
What laboratory signs will indicate a Horse has anaemia?
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
In relation to Equine Anaemia, what is a major cause of death post partum?
Periparturient Haemorrhage- haemorrhage from uterine vessels and reproductive tract during birth
What makes the difference between Periparturient Haemorrhage being fatal and non-fatal?
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
How does a horse get Equine Infectious Anaemia?
It’s a Lentivirus- transmitted via insects or blood contaminated equipment
How do we diagnose Equine Infectious Anaemia?
Coggin’s Test or ELISA
How do we treat Horses with Equine Infectious Anaemia?
Euthanasia or lifelong quarantine
Apart from infections and immune mediated anaemia, how else may a Horse acquire Haemolytic Anaemia?
Drugs e.g. Phenothiazinr caused Heinz Body Formation
Red Maple Leaf Toxicity causes oxidative change of Hb
