Equine abortion

Question 1

Placentitis is a major cause of abortion in mares during the earlier or later stages of pregnancy?

Answer 1

later

Question 2

What is most common route in which bacteria are introduced to the uteroplacental unit?

Answer 2

ascending infections, which result in inflammation and placental detachment at the cervical star region.
-hematogenous infections are also possible (Strep. zoo, E. coli, P. aeruginosa, Klebsilla, Aspergillus)

Question 3

Treatment options of mares with placentitis

Answer 3

1. abx
2. NSAIDs (flunixin) to suppress inflammation
3. Altrenogest (progesterone) to promote uterine quiescence -unknown efficacy
4. clenbuterol (sympathomimetic) to suppress uterine motility -unknown efficacy
   - pentoxyfylline to decrease inflammatory mediators and increase uterine blood flow - unknown efficacy

Question 4

What is the most common virus associated with equine abortions?

Answer 4

equine herpesvirus type 1 (EHV-1)

-also EHV-4 and equine viral arteritis (EVA)

Question 5

What can be done to prevent EHV-1 and abortions?

Answer 5

Vaccination against EHV-1 at month 5,7,9 has been shown to reduce the incidence of EHV-1 induced abortions

Question 6

Any other symptoms with EHV-1?

Answer 6

yes - subclinical to clinical respiratory infections

Question 7

How is the fetus infected by EHV-1?

Answer 7

by either the chorionic vasculature or by inhalation of infected amniotic fluid

Question 8

Diagnosis of EHV-1

Answer 8

examination of the fetus: small necrotic foci on the liver, necrotizing bronchiolitis, intranuclear inclusion bodies on histologic examination
for confirmation:
-virus neutralization tests, indirect immunofluorescence, PCR, virus isolation

Question 9

What if they are born alive with EHV-1?

Answer 9

they will not survive for more than a few hours or days and will demonstrate signs of respiratory distress, icterus, fever, lethargy

Question 10

Treatment of EHV-1

Answer 10

No treatment, although anti-virals may theoretically be of benefit
-most people just vaccinate at the appropriate times

Question 11

Why do twin pregnancies often result in abortion?

Answer 11

there is limited endometrial surface for the allantochorion to attach (diffuse microcotyledonary placenta)

Question 12

What if somehow the twin fetuses are carried to full term?

Answer 12

often one or both of the fetuses are stunted in growth and size from intrauterine growth retardation

Question 13

How does umbilical torsion cause abortion in the mare?

Answer 13

• fetus is able to rotate within the amniotic sac and can result in excessive twisting of the umbilical cord
• results in constriction of the normal flow through the umbilical cord along with edema, hemorrhage and thrombosis