Pregnancy Failure in Equines Flashcards
What three things make up pregnancy failure in mares?
- Conception Failure
- Early Embryonic Death
- Abortion
At what point during the season are you unable to re-breed?
day 35-40
What percentage of pregnancy losses occur in the embro stage?
in thoroughbreds
20%
What percentage of pregnancies are lost during the foetal phase?
12%
What percentage of pregnancies are lost during the perinatal phase?
1%
When is equine abortion most likely to be seen?
6-11 months
What are the three warning signs of abortion in mares?
- Premature lactation
- Vulval relaxation
- Vaginal Discharge
How would you remove twins at day 15?
Manual crushing of the smaller vesicle
re-check repeatedly until day 40
What is acute placentitis?
hyperaemia and haemorrhage > degeneration and necrosis from chorionic villi to surrounding chorioallantois, organisms and toxins then invade and kill the foetus
What is chronic placentitis?
infection extends through the placenta > oedema and thickening of the chorioallantois > gradual separation of the affected chorionic villi
What are the warning signs of placentitis?
premature lactation/ udder development
vaginal discharge
How would you diagnose placentitis?
- Transrectal ultrasound
- Aborted foetus- often retardation
- Send the placenta for histology
How would you prevent placentitis?
- prebreeding assesment of perineal conformation
- endometrial swabs pre-breeding
- intra-uterine medication post-breeding
- ‘caslick’ operation post-breeding
What are the three infectious causes of abortion?
- EHV-1
- Leptospirosis Pomona
- Salmonella Abortus equi
What three notifiable diseases cause abortion?
- EVA
- EIA
- AHS
What is the most common cause of infectious abortion in mares in the UK?
EHV-1
What does EHV-1 Cause?
sudden, rapid abortion with no warning signs,
primary respiratory disease so there may be a history with coughs and nasal discharge
What does EHV-1 look like in the foetus?
grossly
- Excess serosal fluid
- Minute white spots on the liver
- Enlarged spleen
- Soft thymus
What does EHV-1 look like in the placenta?
- Allantochorion, thick and heavy oedema
- Common for chorion to be outside
- Rupture across the body is common
What does EHV-1 look like in histology?
- Necrotic Foci in the liver, lung and adrenal cortex
- Lymphoid tissue necrosis
How would you detect EHV-1 virus?
- Virus isolation from foetal tissues or blood
- PCR- for EHV-1
What is the epidemiology of EHV-1?
- Transmitted via aerosols or fomites
- foetal membranes and vaginal discharge is highly infective
- causes sporadic abortion in vaccinated mares
- causes abortion storms in naive unvaccinated populations
What are the Clinical signs of EVA?
- Pyrexia, Lethargy, depression, Anorexia
- Oedema of limbs and ventral abdomen
- Conjunctivitis and Chemosis
- Nasal discharge
How is swamp fever spread?
Spread via biting flies
(has no known treatment/ vaccine)
How would you diagnose swamp fever?
Coggins blood test
What are the clinical signs of Swamp Fever?
- Pyrexia
- Thrombocytopenia
- Death
What are the two potential post-abortion complications?
- Bacterial placentitis
- Retained whole or part foetal membranes
Name three maternal factors that may cause embryonic abortion
- Oviduct environment
- Age
- Uterine Environment
Name three external factors that may cause embryonic abortion
- Stress
- Inadequate Nutrition
- Toxin ingestion
Name three embryonic factors that may cause embryonic abortion
- Small size
- Morphological defects
- Chromosonal abnormalities
How often would you need to re-check the manual crushing of the embryo?
re-check repeatedly up until day 40
What does EHV-1 look like histologically?
- Necrotic foci in the liver
- Lymphoid tissue necrosis
How would you detect a EHV-1 virus?
- Take sample from foetal tissues or blood
- PCR for EHV-1 takes aroind 8 days
How is EVA most commonly spread in stallions?
Venereal infection in carrier stallions
What does an EVA abortion fetus look like?
- Autolysed but with no specific lesions
- Inform lab when sending off/ suspect EVA
How can you treat EVA?
Mainly supportive care
* Spontaneous recovery in mares
* Stallions may need castrating
How is EVA most likely transmited from male to female?
- Direct transmission during mating
- Contact with the aborted fetus
- Respiratory route
What vaccination can you give an EVA stallion?
- They can be vaccinated is previously proven to be seronegative
What may bacterial placentitis cause?
- persistent bacterial endometriosis
What may retained foetal membranes cause if not dealt with quickly?
Endotoxaemia
* may then get acute severe laminitis due to the endotoxaemia
What do you note when examining the aborted fetus?
- Freshness
- Congenital defects
- Birth trauma
- Meconium staining
- Subcut oedema
