Equine pregnancy Flashcards
Average gestation in the mare?
336 (can be highly variable)
Outline the key events which occur during equine pregnancy
- Fertilisation occurs in ampulla of oviduct
- Day 5-6 embryo enters the uterus
- Embryo migrates around the uterus to day 15-16 - stimulates MRP and prevents PG release
- On day 15-16 embryo fixes in position
- Placental attachment begins at 36 days
- Production and attachment of endometrial cups
- Foetus grows into uterine body after 70-80 days, found mostly in the body until 6-7 months , after which it is so large it occupies part of the horn again.
How long do endometrial cups support pregnancy?
What is their role?
From day 35 to five months pregnancy
Release eCG which maintains the primary CL and encourages secondary CLs to form - P4 release
From what day is the equine pregnancy maintained by foetal progesterone?
By around day 200 (when endometrial cups and CLs have regressed)
Why should attempts to abort foals be done before 35 days of pregnancy?
At this day endometrial cups begin to develop, they are maintained even if the foal dies and maintain progesterone levels in the reproductive tract ceasing cyclicity (probably won’t cycle until next season)
Around what day would you tease a mare as a PD tool?
day 14-20 - check with stallion and receptivity
What endocrine tests are used for pregnancy diagnosis is horses?
Blood eCG – from days 45-90 (beware, they persist even with foal death)
Oestrone sulphate – days 120 onwards – also indicates foetal viability
Urine sample – Oestrone sulphate in urine after day 150
Faecal samples for oestrone sulphate
At what day should you be able to ballot the foal on rectal palpation?
day 120
How can you distinguish a uterine cyst from a conceptus on ultrasound exam?
The conceptus is migratory from day 0-16
Outline a possible scan routine for PDing a mare.
- First scan 15-16 days post mating – Check for pregnancy or return to oestrus, check for twins – can reduce whilst embryos motile and can be separated
- Second scan day 24-26 - heartbeat visible, chance of embryonic death lessened, still can reduce twins (more difficult), before cups established – can terminate pregnancy
- Third scan 6 weeks (optional) - embryonic death unlikely now
Distinguish between early embryonic death, abortion and still birth.
What can cause them?
- Early embryonic death – from fertilisation to day 40
- Foetal abnormalities, breeding on foal heat, uterine fibrosis/ inflammation
- Abortion – from day 40-300
- Herpes - EHV1
- Stillbirth – from day 300 onwards
What virus causes late abortion in horses?
EHV1 - 5 months onwards
Oral/ inhalation contamination (foetal membranes)
Vaccinate at 5, 7 and 9 months pregnancy
This notifiable disease causes t cell shedding in stallions
Equine Viral arteritis
Stallions and mares (bred 14 days previously) MUST be reported
There is a vaccine BUT seropositive semen would not be USA accepted!
Bacterial abortion
E.coli, streps, staphs, Salmonella
Introduced by ascending infection, at breeding or by haematogenous spread
Fungal cause of abortion in horses?
RARE
Aspergillus
