Mare pregnant

Question 1

Manipulation of oestrus

Role of prostaglandin drugs

Answer 1

Induce luteolysis in receptive corpus luteum.
Oestrus will commence 3-5 days post injection – but variable depending on stage of breeding season.
Side effects not uncommon – in 30 ins-1hr transient colic, sweating, diarrhoea etc – can be dramatic and worrying but these pass over
NOT for anything in foal

Question 2

MoO

Role of progesterones

Answer 2

Induce luteolysis in receptive corpus luteum.
Oestrus will commence 3-5 days post injection – but variable depending on stage of breeding season.
Side effects not uncommon – in 30 ins-1hr transient colic, sweating, diarrhoea etc – can be dramatic and worrying but these pass over
NOT for anything in foal

Question 3

MoO

Role of oestrogens

Answer 3

Induce behavioural signs of oestrus but not true oestrus.

Only useful for maintaining “teaser mares” for AI collection.

Question 4

MoO

Role of chorionic Gonadotrphin

Answer 4

If given during oestrus will induce the dominant follicle (>35mm) to ovulate within 24 hours.

Question 5

MoO role of GnRH analogue e.g. deslorelin

Answer 5

Hormone implant given sub-cut when follicle >30mm – should induce ovulation within 48 hours in most mares

Question 6

MoO light changing

Answer 6

artificial light over winter to bring breeding period forward

• 16 hrs light 8 hrs dark from late autumn
• mares ovulate 8-19 weeks later

Question 7

Why is oestrus suppression of a naughty mare difficult

Answer 7

Behaviour problem may actually be non-sexual in nature (poor training, orthopaedic pain etc)
Behaviour maybe sexual but not hormone related (eg social “flirting”.even if out of oestrus)
Some mare sex hormones also produced by brain and adrenals
Treatment may damage potential future breeding career
Need to explain to owner this is difficult. Discuss limitations

Question 8

What to do before start to use hormones to suppress oestrus?

Answer 8

Scan ovaries/uterus
Check for Granulosa cell tumour (blood sample)
Keep diary of problems – is it cyclical?
Rule out other causes of bad behaviour if possible.

Question 9

When to serve mare and why?

Answer 9

24-48 hours prior to ovulation.

as oestrus ceases within 24 hrs of ovulation
unfertilised oocyte viable for only 12 hrs post ovulation
Spermatozoa viable in oviduct for 48 hrs once in mare

Question 10

mare in oestrus ahs

Answer 10

Dominant follicle >25mm on one ovary
Uterine oedema
Soft oedematous cervix
Behavioural signs of oestrus

Question 11

When scan?

Answer 11

12-24 hrs after mating (ovulated or not, one or 2 ovulations? endometritis and treat)

Can scan at 10 days but embryonic death likely up to 14 so not worth it

conceptus motile to day 16 therefore easy to distinguish from cyst

Scan 14-18 days after last mating AND 28-35 days after last mating to reduce risk of missing twin

After day 30-35 endometrial cup production will prevent mare returning to oestrus is pregnant terminated

Question 12

Gestation

Answer 12

336 days

Question 13

Induction aboriton before 3 months

after 3 months

Answer 13

before 3 months: Prostaglandin injection = aboriton 5-8 days after

After = Repeated prostaglandin injections 2X day

Question 14

pregnancy diagnosis

Answer 14

1. Rectal manipulation (early as 20, usually 40 days)
2. US
3. Lab test
4. failure to return to oestrus signs

Question 15

Lab tests

Answer 15

1. blood sample to detect egg from cups from day 45-60 however this just detects presence of cups not encc live foal
   Oestrone sulphate from day 120

Urine sample = oestrogen sulphate in urine after 150 day