Equine Pregnancy Flashcards

1
Q

How long is an equine pregnancy?

A

336days from mating

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2
Q

Where does fertilisation occur in the mare? + Movement / attachment?

A

*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

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3
Q

When does maternal recongniton of pregnancy occur?

A
  • 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
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4
Q

What are the problems with endometrial cups?

A

*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

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5
Q

How can you diagnose pregnancy?

A
  1. Failure to return to oestrus
  2. Laboratory tests
  3. Manual rectal exam
  4. Ultrasound
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6
Q

What does failure to return to oestrus say? When?

A

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

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7
Q

What lab tests could be done? from when?

A

*eCG - from day 45-90
*Oestrone sulphate from day 120
*Urine sample from day 150

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8
Q

How is manual rectal palpation carried out? When?

A

*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

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9
Q

When would you perform rectal ultrasonography? Why?

A

*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

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10
Q

What is distinctive with ultrasonography of foetus?

A

*White bits at top and bottom of black hollow cavity on ultrasonography

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11
Q

From what date can you perform transabdominal ultrasonography?

A
  • From 6 months onwards
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12
Q

When does early embryonic death, abortion + stillbirth occur?

A
  • Early embryonic death - from fertilisation to day 40
  • Abortion - from day 40 - 300
  • Stillbirth - from day 300 onwards
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13
Q

What can cause failure of pregnancy?

A
  • Early embryonic death
  • Viral - EHV, EVA
  • Bacterial
  • Fungal
  • Twins
  • Maternal illness / stress
  • Foetal abnormalities
  • Umbilical torsion
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14
Q

What can cause early embryonic death? Dx?

A
  • 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
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15
Q

When does EHV-1 cause abortion?

A

*Usually late term (>5months)

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16
Q

How is EHV-1 diagnosed, treated + prevented?

A
  • 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
17
Q

When is EVA notifiable? Prevention?

A

*Stallions + mares mated in last 14days
*Stallions become persistently infected shedders

  • Prevention = vaccine
18
Q

What are agents of bacterial abortion? Causes? Tx?

A
  • Strep, E. coli, Staph
  • Causes = ascending infection from cervix, haematogenous spread + intro of bacteria at breeding
  • Tx = antibiotics / NSAIDs - often too late
19
Q

What can cause fungal abortion?

A

*Aspergillus spp - rare

20
Q

Why can twin pregnancy cause failure of pregnancy?

A

*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

21
Q

What kind of twins are more likely to die?

A

*Twins with one in each horn (bilateral) as more likely to get reasonable size before compete for uterus space

22
Q

How can the rectum be relaxed for crushing of a twin?

A

*sedatives / hyoscine

23
Q

What are signs of abortion?

A
  • Maybe none
  • Vaginal discharge
  • Running milk - placentitis causes early lactation
  • Colic / foaling signs
24
Q

How would you investigate abortion?

A

*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

25
Q

How can you induce abortion?

A

*Before 3 months = Prostaglandin injection
*After 3 months = Repeated prostaglandin injections, Dilation of cervix + uterine lavage, Dislocation foetal neck per rectum

26
Q

How can you induce foaling?

A

*Oxytocin (1-2ml) every 15-20min till delivery starts
-however not done often - premature foal bad

27
Q

What are the risks of inducing foaling?

A

*Uterine rupture
*Dystocia
*Foal immaturity
*Retained membranes