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Theriogenology > Non-infectious Equine Infertility > Flashcards

Non-infectious Equine Infertility Flashcards

1
Q

Natural reduction usually occurs ____

A

After day 16

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2
Q

Twinning

A

Almost always results in late term abortion

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3
Q

Late term abortion can lead to

A
  • dystocia
  • retained placenta
  • delayed uterine involution
  • metritis
  • death of both twins, and/or mare
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4
Q

Source of twins

A
  • mostly dizygotic from multiple ovulations

- reported monozygotic

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5
Q

____ have highest incidence of double ovulations (16%)

A

Thoroughbreds

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6
Q

Synchronous vs asynchornous ovulations

A
  • 2 ovulations within 24 hrs: synchronous

- 2 ovulations within >24 hrs: asynchronous

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7
Q

Incidence of twins

A
  • 3-11% of mares conceive twins
  • account for 1-2% of equine births –> 14% of live foals still alive after 2 weeks
  • fetal and perinatal losses approach 90%
  • up to 30% of abortions are attributable to twins –> 2nd to placentitis!!
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8
Q

Breed affects

A
  • thoroughbreds and drafts (15-25%)

- standardbred, quarter horse, appaloosa (5-15%)

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9
Q

Seasonal imact

A
  • Jan-March (7%)

- April-May (22%) –> higher incidence during physiological breeding season

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10
Q

Reproductive status

A

Rare to see twins following foal heat mating

- rarely seen in mares foaling early in the year

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11
Q

Other influencing factors

A
  • body condition

- heritability: seen in certain lines

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12
Q

Ultrasound

A

Led to decrease in number of twin pregnancies in the last 30 years
- can detect twins much earlier

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13
Q

Causes of embryo/fetal losses

A
  • lack of contact with endometrium
  • decreased nutrient exchange
  • placental insufficiency
  • unilateral twins (lost usually by 40 days)
  • bilateral twins (loss by 5-9 months)
  • natural reduction is efficient, especially in unilateral twins
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14
Q

_____ has no benefit

A

Breeding strategies

  • breed regardless of # of follicles
  • don’t try to catch 2nd follicle by passing the 1st follicle
  • advantage of greater preg rates when double ovulations occur, so breed anyway
  • use ovulation induction agents as you normally would
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15
Q

Post breeding exam

A

Continue to check mare to determine if additional ovulations occur

  • record ovulations
  • document location of uterine cysts
  • plan pregnancy checks early if twins are suspected/anticipated (13-14 day check)
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16
Q

Failure to detect twins

A
  • endometrial cysts (usually not spherical)
  • pregnancy detection occurring too early to detect 2nd embryo
  • lack of thorough ultrasound
  • poor image quality
  • immediately adjacent vesicles that appear as one
17
Q

Pregnancy check

A

Ultrasound mare on day 13-15 post ovulation

  • vesicles are still mobile at this point
  • if 2 vesicles found, twins are diagnosed –> manipulate/manually crush 1 twin
  • recheck in 2-3 days if possible –> crush twin if discovered, assure remaining twin is growing/viable
18
Q

Problems occur if mare ______

A

Is not checked until 35-40 days

  • eCG being produced by cups
  • if pregnancy is terminated at this point, the mare won’t cycle predictably that year
  • season is lost
19
Q

Twin reduction options depends on _______

A
  • stage of pregnancy at time of diagnosis
  • location of embryonic vesicles
  • management factors
  • owners risk tolerance
  • time of breeding season
  • clinician expertise
  • equipment available
20
Q

Options - before fixation

A

Days 12-16

  • natural reduction
  • manual crushing
21
Q

Options - after fixation

A

Days 17+

  • natural reduction
  • manual crushing
  • US guided aspiration or cardiac puncture
  • cranio-cervical dislocation
22
Q

Day 14-16

A

Crush one vesicle

  • move smaller vesicle to tip of one horn and crush
  • 93% success rate
  • if vesicles are adjacent just wait 10-20 minutes for them to separate naturally
23
Q

What is success?

A
  • elimination of a single conceptus
  • carrying to term the remaining conceptus
  • with delivery of a normal viable foal
24
Q

Success rate is ______ proportional to the time you start management

A

Inversely

25
Q

Day 17-34 of gestation - bilateral twins

A
  • crush one vesicle –> 90% success rate, may give NSAIDs
  • transvaginal US guided aspiration –> 75% success rate
  • do nothing –> 0% chance of natural reduction
26
Q

Day 17-34 - unilateral twins

A
  • wait until day 33 –> 77% should naturally reduce
  • abort entire pregnancy with prostaglandins
  • transvaginal US guided aspiration –> 33% success rate
27
Q

Days 35-60 - bilateral twins

A
  • crush one vesicle –> 25% success rate, difficult to perform
  • transvaginal US aspiration –> 75% success rate
  • abort with prostaglandins –> requires multiple injections, season will be lost b/c of eCG presence
28
Q

Days 35-60 - unilateral twins

A
  • do nothing –> 77% should reduce naturally by day 40
  • abort with prostaglandins
  • transvaginal US aspiration –> 33% success at 45 days
29
Q

Day 61-90

A

If twins survive, abortion is likely despite location

  • 70% will abort if they make it past 90 days
  • abort with prostaglandins –> multiple, daily injections to effect, mare will have more time to recover prior to next breeding season
  • US guided fetal cardiac puncture –> 33% success rate
30
Q

Cranio-cervical dislocation

A

Performed between 55-110 days of gestation

  • trans-rectal: 55-90 days
  • intra-abdominal: 65-110 days
  • success rate of 60% with a birth of a single normal sized, healthy foal
31
Q

Body pregnancy

A

Embryo becomes fixed in uterine body

  • placenta is unable to fully expand into both uterine horns
  • placental insufficiency results in late term abortion (7-8 months)
32
Q

Hypoleuteism

A

Progesterone levels insufficient to support pregnancy

  • progesterone below 2.0 ng/ml
  • placenta begins taking over progestagen production at 120 days and is only source after 150
  • can be an early pregnancy problem
  • treatment involves supplementation with altrenogest
33
Q

Umbilical cord torsion

A

Normal twisting (2-4 twists) is common

  • average cord length should be 50-60 cm
  • excessive twisting results in vascular compromise leading to fetal death
  • abortion/stillbirth
  • rare cause of pregnancy loss in US, seen in Europe

Theriogenology (25 decks)

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