Equine Neonatal Diseases Flashcards
List some equine neonatal diseases…
Failure of passive transfer Perinatal asphyxia syndrome Sepsis Neonatal isoerythrolysis Uroperitoneum Infectious and non-infectious D+ Colic Respiratory diseases (neonatal respiratory distress syndrome, infectious pneumonia, persistent foetal circulation)
When do foals produce functional lymphocytes?
Function T lymphocytes - 100 days gestation
Function B lymphocytes - 200 days gestation
Are foal capable of a complete immunological response?
Yes - they have developed innate and adaptive components
BUT they don’t have any antibodies from their mother (no transfer via placenta)
How do foals get their antibodies?
Almost entirely on absorption of preformed antibodies from colostrum
Describe equine colostrum…
Produced in the last 2 weeks of gestation
Soluble components
Cellular components (lympho, macro, neutro, epithelial)
What are the soluble components of equine colostrum?
IgG, IgM, IgA Hormones Growth factors Cytokines Lactoferrin CD14 Enzmyes
What does the presence of maternal antibodies suppress the production on in foals?
Foals own Ig’s
Vaccination should be carried out after maternal Igs have declined.
What volume of colostrum should foals ingest in the first 3 hours of life?
1-2 litres of colostrum
When is Ig measurable in the serum of foals?
4-6 hours
Peaks at 18-24hrs
Describe the foal’s immune system in terms of colostrum intake…
Specialised enterocytes allow absorption of Ig via pinocytosis 12-24hrs
Maximal efficacy of absorption after birth
Half life maternal antibodies = 20-30d
Foal’s own Igs production reaches adult levels at 5-10 months
Very susceptible to disease 1-2months
Why is failure of passive transfer a problem in foals?
Predisposes to infectious disease
Especially bacteraemia, sepsis, septic arthritis, diarrhoea, pneumonia, meningitis
What are the maternal factors associated with failure of passive transfer in foals?
Lack of colostrum (premature lactation)
Poor colostrum quality (low conc of IgG (specific gravity <1.060 or <3000mg/dL = 30g/L)
What are the factors associated with the foal resulting in failure of passive transfer?
Lack of colostrum intake by the foal
- Inability to nurse (sepsis, perinatal asphyxia, ortho)
- Foal rejected by mare
Lack of colostrum absorption
- Colostrum ingested too late
- Gastrointestinal disease (hypoxic damage)
What values are associated with complete FPT, partial FTP and successful transfer in foals?
Complete FTP
< 4.0g/L
Partial FTP
4.0 - 8.0 g/L
Successful tranfer
> 8.0 g/L
How can FTP be diagnosed in foals?
History
- Problems standing or never stood
- Not nursing until 8-12 hours of age
- Rejected by mare
Colostrum examination
SG <1.060
IgG concentration in blood
- SNAP test (ELISA)
How can you treat FPT with a nasogastric tube in the foal?
Foal <12 hours old and no systemic signs
1.0-20L of equine colostrum (SG >1.060)
200-400ml at the time
Use nasogastric tube, not syringe or bottle => risk of aspiration
How can you treat FPT with plasma in the foal?
IV Plasma (1-2L)
- Foal >8hours
- Foal showing systemic signs
- No high quality colostrum
Plasma administration
- Use plasma giving set and monitor carefully for signs of plasma reaction
- Administer 1 drop per sec (3ml/min)
- Check heart rate, respiratory rate, and temperature every 5 minutes
- No reaction after 15 minutes: administer quickly
How should you manage a plasma reaction in foals?
Stop transfusion
Give flunixin meglumine +/- IV fluids
Wait 1-2 hours, restart infusion slowly
If reaction persists use different plasma batch or donor
What is neonatal isoerythrolysis?
Immune-mediated haemolytic anaemia of newborn foals
What causes neonatal isoerythrolysis?
Caused by incompatibility between mare and foal’s blood group
- Mare produced antibodies against foals RBC antigens
- Antibodies are secreted into the colostrum and absorbed by the foal
- Antibodies adhere to and destroy foal’s RBCS
What are the prerequisites for neonatal isoerytholysis?
Two stage process featuring 2 pregnancies.
Number One
Foal 1 inherits RBC antigens antigens (Aa, Qa) from Sire.
Mare is Aa and Qa negative
⇓
Mare exposed to foal’s RBC (transplacental haemorrhage, parturition..)
⇓
Mare produces antibodies against Aa or Qa
Number Two
Foal 2 inherits RBC antigens (Aa, Qa) from Sire.
Mare has built up antibodies against Aa and Qa
⇓
Foal ingests antibodies with colostrum: absorbed into circulation
⇓
Antibodies coat RBC ⇒ intra- and extra- vascular haemolysis
When do clinical signs of neonatal isoerythrolysis develop?
At 1 - 12 days (usually under 3)
What does the onset and severity of neonatal isoerythrolysis depend on?
Amount of ABs ingested
Affinity of antibodies for antigen on RBC
Type of alloantibody: Aa > Qa
What are the types of haemolysis associated with neonatal isoerythrolysis?
Intra and extravascular
