Equine Pregnancy Flashcards
How long is an equine pregnancy?
336days from mating
Where does fertilisation occur in the mare? + Movement / attachment?
*Ampulla of oviduct
*Embryo remains in oviduct for 5-6 days when it enters uterus
*Then migrates around uterus up to day 15-16 - movement essential for maternal recognition of pregnancy + prevent= PG release
*On day 15-16 embryo fixed to base of horn + placental attachment post 36days
*Grows in uterine body after 70-80 days -for 6-7months then so big that it occupies part of horn
When does maternal recongniton of pregnancy occur?
- 14 days
- CL produces progesterone
- Endometrial cups secrete eCG from day 35 which maintains primary CL + 2ndary CL formation
*After day 200 CLs degraded + pregnancy maintained by foetal-placental progesterone
What are the problems with endometrial cups?
*Once in place will not regress for 100-150days
*If foal has died - mare will not come into oestrus
*Abortion must be done before day 35
How can you diagnose pregnancy?
- Failure to return to oestrus
- Laboratory tests
- Manual rectal exam
- Ultrasound
What does failure to return to oestrus say? When?
Failure to return to oestrus
* Particularly at day 14-21 after mating.
* Initial screening test but not definitive
* Mares may not show oestrus for behavioural reasons
* Conversely some mares display signs of oestrus during pregnancy
What lab tests could be done? from when?
*eCG - from day 45-90
*Oestrone sulphate from day 120
*Urine sample from day 150
How is manual rectal palpation carried out? When?
*Possible at day 20 (IF v skilled)
*Usually left until day 40
*Feel foetus by day 120
*Replaced by scanning - only used in late pregnancy now
When would you perform rectal ultrasonography? Why?
*Can be done from day 10 - usually don’t scan too early
*Early embryonic death highest in first 14days
*Scan from day 16 - can see if twins + get rid
*Second scan day 24-26 = heartbeat, still can reduce twins + before cups
*Third scan = 6 weeks - just reassess
What is distinctive with ultrasonography of foetus?
*White bits at top and bottom of black hollow cavity on ultrasonography
From what date can you perform transabdominal ultrasonography?
- From 6 months onwards
When does early embryonic death, abortion + stillbirth occur?
- Early embryonic death - from fertilisation to day 40
- Abortion - from day 40 - 300
- Stillbirth - from day 300 onwards
What can cause failure of pregnancy?
- Early embryonic death
- Viral - EHV, EVA
- Bacterial
- Fungal
- Twins
- Maternal illness / stress
- Foetal abnormalities
- Umbilical torsion
What can cause early embryonic death? Dx?
- Congenital / genetic abnormalities
- Breeding on foal heat - first season after foaling
- Uterine environmental problems - fibrosis / endometritis
- Dx = empty on repeat scan / abnormal size or shape conceptus on scan
When does EHV-1 cause abortion?
*Usually late term (>5months)
How is EHV-1 diagnosed, treated + prevented?
- Dx = nasopharyngeal swabs for horses showing respiratory signs
- Tx = none - isolate + disinfect + separate pregnant mares from youngstock
- Prevention = Vaccination - 5,7 + 9 months of pregnancy
When is EVA notifiable? Prevention?
*Stallions + mares mated in last 14days
*Stallions become persistently infected shedders
- Prevention = vaccine
What are agents of bacterial abortion? Causes? Tx?
- Strep, E. coli, Staph
- Causes = ascending infection from cervix, haematogenous spread + intro of bacteria at breeding
- Tx = antibiotics / NSAIDs - often too late
What can cause fungal abortion?
*Aspergillus spp - rare
Why can twin pregnancy cause failure of pregnancy?
*Twins compete with one another for attachment space (placenta need 70% contact with uterus) - one will run out of space in early pregnancy + die
*Other twin will continue to grow until deprived of space by remnant of dead twin + is aborted
What kind of twins are more likely to die?
*Twins with one in each horn (bilateral) as more likely to get reasonable size before compete for uterus space
How can the rectum be relaxed for crushing of a twin?
*sedatives / hyoscine
What are signs of abortion?
- Maybe none
- Vaginal discharge
- Running milk - placentitis causes early lactation
- Colic / foaling signs
How would you investigate abortion?
*Send whole carcass + placenta to pathologist
*Exam placenta + cord
*External exam + internal exam
*Sample chorion, thymus, liver, lung, spleen
*Don’t sample mare - not very useful
How can you induce abortion?
*Before 3 months = Prostaglandin injection
*After 3 months = Repeated prostaglandin injections, Dilation of cervix + uterine lavage, Dislocation foetal neck per rectum
How can you induce foaling?
*Oxytocin (1-2ml) every 15-20min till delivery starts
-however not done often - premature foal bad
What are the risks of inducing foaling?
*Uterine rupture
*Dystocia
*Foal immaturity
*Retained membranes
