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Theriogenology > Repro Physiology > Flashcards

Repro Physiology Flashcards

1
Q

What is the first sign of pregnancy for palpation?

A

Bulge on the ventral aspect of the horn

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2
Q

What is responsible for triggering ovulation?

A

LH

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3
Q

What suppresses LH?

A

Progesterone

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4
Q

Puberty occurs around ______

A

2 years of age

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5
Q

Polyestrus

A

Long day breeders

  • northern hemisphere: spring/summer
  • southern hemisphere: fall/winter
  • cycle from March-October (20% will cycle year round)
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6
Q

Mare will ______ during the breeding season

A

Repeatedly cycle

- recurring estrus on a predictable interval until pregnant or season ends

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7
Q

Estrous cycle

A

From ovulation to subsequent ovulation

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8
Q

Follicular phase

A

Estrus

  • estrogen is dominant
  • estrus ends 18-24 hrs after ovulation
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9
Q

Luteal phase

A

Diestrus

- starts with ovulation until luteolysis

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10
Q

Ovulation to ovulation is ______

A

21 days

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11
Q

Estrus

A

Behavioral signs associated with impending ovulation

  • receptivity to male
  • occurs when progesterone is low (after luteolysis)
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12
Q

Give _____ if you do not want a mare to show estrus signs

A

Progesterone

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13
Q

Jump mare

A

Mare that has had her ovaries removed, so progesterone levels are nonexistent

  • will be passive whenever a stallion is presented
  • can collect stallions whenever needed
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14
Q

Entire estrous cycle lasts

A

20-24 days

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15
Q

Estrus lasts

A

4-7 days

  • single follicular wave is most common in equines
  • cows have 2-4 waves
  • dominant hormone is estrogen
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16
Q

Follicular wave

A

Cohort of immature primordial follicles that emerge until 1 becomes dominant and suppresses all others

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17
Q

Diestrus lasts

A

14-15 days

  • consistent length in equines
  • dominant hormone is progesterone
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18
Q

Mares ovulate _______ before going out of heat or estrus

A

24-48 hrs

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19
Q

Ovulation

A

Occurs prior to the end of estrus

  • follicle size at ovulation is generally 40-45 mm
  • size can be breed dependent
  • double ovulation occur 16% (twinning)
20
Q

______ follows ovulation

A

Luteal phase

21
Q

Mares ovulate_____, toward the ______

A

Inward; ovulation fossa

22
Q

Predicting ovulation

A

Used for breeding purposes

  • follicles grow 3-4 mm per day
  • follicle becomes soft
  • loss of spherical shape with development of apex
  • serrations in granulosa layer
23
Q

Teasing with stallion - estrus

A
  • tail raise
  • squat, tip pelvis
  • urinate
  • evert clitoris
24
Q

Exam of ovaries - estrus

A
  • large follicle, may be soft
  • follicle may be triangular w/ scalloped edges on US if mare is near ovulation
  • no CL on US
25
Q

Exam of uterus - estrus

A
  • relaxed w/ soft texture

- edematous endometrial folds visible on US

26
Q

Exam of cervix - estrus

A
  • shortening, widening
  • relaxed w/ soft texture
  • pink and drooping on vaginal floor
  • lumen open 1-3 fingers on digital exam per vagina
27
Q

Teasing w/ stallion - diestrus

A
  • switch tail
  • kick, squeal
  • attempt to bite
  • move away
28
Q

Exam of ovaries - diestrus

A
  • presence of CL on US

- follicles of varying sizes, may be large

29
Q

Exam of uterus - diestrus

A
  • firm texture (good tone)

- uniform echogenicity on US

30
Q

Exam of cervix - diestrus

A
  • long and narrow, firm texture
  • pale, dry, centrally located in cranial vagina
  • closed lumen on digital exam
31
Q

Seasonality in mares is regulated by ______

A

Photoperiod

  • improved efficiency during periods of increased daylight
  • length of photoperiod modulates GnRH secretion
32
Q

During short days, _____ secretes ______

A

Pineal gland; melatonin

- suppresses GnRH

33
Q

During long days ______

A

Little melatonin is released, suppression is removed

34
Q

Melatonin

A

Released when it is dark!

  • inhibitory effect on GnRH in the mare
  • secreted by pineal gland, under control by retina’s detection of light via photoreceptors
35
Q

Melatonin’s effects

A
  • short days: pineal gland secretes more melatonin so GnRH is inhibited (anestrus)
  • long days: pineal gland releases little melatonin and GnRH is not inhibited (mare cycle’s)
36
Q

Vernal transition

A

Period of time during spring and fall when mare is transitioning from anestrus to cyclicity and reverse in the fall

  • ambiguous signs of estrus seen
  • ends w/ first ovulation of the season
37
Q

Spring transition

A
  • erratic estrus behavior
  • erratic follicular growth
  • anovulation
  • improper breedings
38
Q

Stallion repro physiology

A

Puberty at 2 years

- seasonal pattern of sperm production is evident, but they never stop producing

39
Q

_____ is the physiological breeding season for horses

A

April-Sept

- best fertility in May-July

40
Q

_____ is autumn transition

A

Oct-Nov

- going out of season

41
Q

______ is winter anestrus

A

Dec-Jan

  • no signs of estrus
  • little to no follicular activity
42
Q

_____ is spring transition

A

Feb-March

- coming into season

43
Q

Imposed breeding season

A

Jockey club states that all foals are 1 year of age on Jan 1st

  • larger foals top the sales
  • breeders want to have the largest foals
  • pushed to breed mares when environmental cues say they shouldn’t
44
Q

Lighting schemes

A

Place mares under lights beginning Dec 1st (16 hrs daily)

  • continue for 60 days
  • photoperiod is manipulated
  • mares enter vernal transition sooner –> first ovulation sooner
45
Q

Foal heat

A

First postpartum estrus

  • occurs around 10 days postpartum
  • fertility is adequate in most cases
46
Q

Backing up a mare

A

Have her foal earlier in subsequent years than the current year

  • gestation length of approx 340 days
  • to keep her around the same foaling date, she would need to conceive within 25 days of foaling

Theriogenology (25 decks)

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