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541 (sex class) > equine 1 > Flashcards

equine 1 Flashcards

1
Q

horses have what kind of estrous cycle?

A

seasonal, polyestrous, long day breeders

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2
Q

how long is the mare’s estrous cycle?

A

21 days, although estrus duration varies with season (avg 7 days)

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3
Q

ovulation occurs ______ days ____(before/after) behavioural estrus ends.

A

1-2 days before

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4
Q

when is the mare’s breeding season?

A

summer (may-aug)

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5
Q

transition periods in the mare occur when?

A

fall and spring

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6
Q

what is transition in the mare?

A

period of time when ovaries transition between estrus and anestrus

may see behaviour signs of estrus and stallion receptivity

not usually correlated with ovulations

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7
Q

why are transition periods in the mare clinically important?

A
  • unusable to be bred during these times; can delay breeding
  • mare behaviour can be problematic for owners
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8
Q

mares have ___ follicular waves and ovulation occurs during ____.

A

2, estrus

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9
Q

most mares will ovulate a follicule between _____ (size) _____ (time) before the end of estrus.

A

40-50mm
24-48 h

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10
Q

mares show signs of heat _____ after ovulation

A

48 hours

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11
Q

follicle size and length of estrus vary considerably between individuals, breed, age, season, access to teasing, etc. BUT follicles typically grow ____ per day during estrus. why is this important to know?

A

3-5mm/day

give you a baseline for tracking

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12
Q

tell me some estrus activity in the mare

A
  • squealing
  • excess urinating (small streams)
  • winking
  • tail raising
  • posturing with wide hind legs
  • back pain
  • grumpy or cuddly
  • sensitivity to work
  • lack of focus
  • no signs at all

basically, it’s unpredictable!

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13
Q

melatonin ___ with increasing day light

A

decreases

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14
Q

what is the #1 most important controller of seasonal polyestrous breeders?

A

melatonin

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15
Q

tell me how melatonin controls seasonal polyestrous breeders

A
  1. increased light
  2. decreased melatonin
  3. stimulation of GnRH in the hypothalamus
  4. stimulation of the pituitary gland to produce further hormones (FSH & LH)
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16
Q

GnRH is released from where?

A

hypothalamus

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17
Q

what does GnRH do?

A

stimulates the pituitary gland (pars distils), which produces gonadotropins (FHS & LH)

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18
Q

FSH is produced in the ___ in response to ____. what does it do?

A

pituitary gland, GnRH

  • pushes mares out of transition in the spring
  • stimulates follicular growth
  • stimulates granulosa cell development
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19
Q

there are ___ waves of FSH through the mare’s cycle. when are they?

A

2

during diestrus (once at the start and once at the end)

different from other animals

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20
Q

why does FSH peak twice during diestrus?

A

allows for 1-2 waves of follicular development

selection for 1 follicle to be dominant – don’t want twins!

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21
Q

inhibin is produced _____.

A

in the granulosa cells of the dominant follicle

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22
Q

what does inhibin do?

A

serves as a (-) feedback loop to the pituitary gland

inhibits FSH so no other follicles develop
(a method of self-selection ensuring one follicle develops)

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23
Q

estrogen is produced by ____, when?

A

mature follicles, nearing estrus (20-25mm)

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24
Q

what does estrogen do?

A
  • stimulates behavioural response in the brain
  • estrus activity
  • relaxes cervix
  • increases smooth muscle activity in the uterus to prepare to transport sperm
  • stimulates the pituitary gland to reduce FSH production and increase LH production
  • increases edema of the uterus, vagina, and vulvar lips
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25
Q

uterine edema is at its max when?

A

24 hours before ovulation

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26
Q

tell me what’s going on in these ultrasound pictures.

A

from L to R, going from no edema to lots of uterine edema (estrus)

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27
Q

LH is produced in the _____. what does it do?

A
  • pituitary gland
  • facilitates maturation of the dominant follicle (prepares to ovulate)
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28
Q

LH peaks when?

A

2 days post ovulation in the mare

different from other animals

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29
Q

LH surge can be influenced by…?

A

teasing/stallion contact

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30
Q

LH only works on what kind of follicles?

A

mature follicles greater than 35 mm (they have the LH receptors)

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31
Q

LH signifies the beginning of what?

A

luteal phase

CH forms in the ovulation fossa which matures to a CL

CL controls diestrus or pregnancy

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32
Q

progesterone is primarily produced by ____

A

the CL

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33
Q

progesterone ____ after ovulation

A

increases

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34
Q

what does progesterone do?

A
  • acts to inhibit further estrus stimulating hormones (FSH & LH)
  • prepares uterus for pregnancy (reduces contractility to smooth muscle in uterus, stimulates tightening/contraction of cervix)
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35
Q

what does progesterone do during diestrus? what about during pregnancy?

A

remains high for both

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36
Q

if the mare is not pregnant after ovulating, what does the lining of the endometrium produce?

A

prostaglandin (PGF2 alpha)

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37
Q

what does PGF2 alpha do?

A

destroys the CL, thus reducing the amount of progesterone

allows for another cycle of FSH to begin

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38
Q

tell me what the sex hormones are doing during a mare’s cycle (estrogen, progesterone, LH, FSH)

A

estrus:
- estrogen peaks
- LH rises
- progesterone low
- FSH low

diestrus:
- FSH peaks twice
- estrogen low
- progesterone peaks + plateaus for all of diestrus
- LH peaks 1-2 days after ovulation (1-2 days into diestrus), then is low

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39
Q

tell me what the hormones are doing during spring transition in the mare

A
  • decrease melatonin
  • increase GnRH
  • increase FSH

irregular heats w/o ovulation

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40
Q

tell me what the hormones are doing during the breeding season in the mare

A
  • decrease melatonin
  • increase GnRH
  • increase FSH, LH

21 day cycle

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41
Q

tell me what the hormones are doing during fall transision

A
  • increase melatonin
  • decrease GnRH
  • decrease FSH, LH

persistent follicles

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42
Q

tell me what the hormones are doing during anestrus (winter)

A
  • increase melatonin
  • decrease GnRH
  • decrease FSH, LH

flaccid uterus, small ovaries

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43
Q

tell me what parameters you can use to predict ovulation in the mare

A
  • follicular diameter
  • uterine edema
  • change in follicular shape
  • thickening of follicular wall
  • softening of the follicle followed by involution
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44
Q

tell me how to use follicular diameter to predict ovulation in the mare

A

35-60mm
basically 35mm or greater = ovulation

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45
Q

tell me how to use uterine edema to predict ovulation in the mare

A

edema maximized 24-36 hours prior to ovulation, decreases just before ovulation

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46
Q

tell me how to use change in follicular shape to predict ovulation in the mare

A

pointed on 1 side - becomes irregular

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47
Q

tell me how to use thickening of follicular wall to predict ovulation in the mare

A

follicular wall thickens - starting to leutenize

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48
Q

during ovulation, the follicular tone ___ and the follicular size ____

A

tone: softens
size: >35 mm followed by involution

49
Q

why do we control the mare’s estrous cycle?

A
  • to get them pregnant
  • cycle becomes more predictable if we manipulate
  • to work around show times
  • so the vet can have a normal work schedule lmao
50
Q

what parts of the estrus cycle are amenable to manipulation?

A
  • prostaglandin
  • ovulation
  • progesterone
  • melatonin
51
Q

how do you induce ovulation in the mare?

A

hCG, deslorelin, or GnRH analogs

52
Q

how do you use hCG to induce ovulation in the mare?

when does ovulation happen after admin?

A

follicle has to be ≥35mm (because it has action on LH and the follicle needs to be big enough for the LH follicles)

ovulation happens 36 hours after admin

53
Q

why do we use GnRH analogs instead of native GnRH?

A

analogs have higher half life and can be a single shot only

54
Q

how do deslorelin/GnRH analogs induce ovulation?

when does ovulation happen after admin?

A

induces release of endogenous LH

ovulation within ~40 hours

55
Q

what is short cycling?

A

interrupting diestrus

56
Q

how do you interrupt diestrus in the mare?

A

PGF2 alpha
a “hot shot”

57
Q

after you give PGF 2 alpha to short cycle, what happens?

A

CL will response 5 days after ovulation

You give hot shot 5 days into diestrus, mares enter estrus in 3 to 4 days, and ovulation occurs within 7 to 10 days.

58
Q

when is PGF2 alpha as a hot shot contraindicated?

A

when there is pregnancy. always check before giving hot shot!

59
Q

How do you prolong diestrus?

A

exogenous progesterone analogs, like altrenogest (Regumate)

60
Q

What are exogenous progesterone analogs used for?

A

prolonging diestrus:
- used to manage the transition period
- used to predict estrus during show season
- used to suppress all estrus activity

61
Q

CAUTION WHEN USING REGUMATE/ALTRENOGEST! why ?

A

you can absorb through skin and chronic use affects human cycling - women have to be careful!

62
Q

mares start cycling when in the spring?

A

late march/early April

spring equinox!

63
Q

which can we manipulate, spring or fall transition? or both?

A

spring

64
Q

why is there follicular development without ovulation during the spring transition?

A

LH lags behind FSH

65
Q

during the fall transition, which declines first, LH or FSH? what does this mean?

A

LH
means follicular growth without ovulation

66
Q

what is an autumn follicle?

A

follicle with large diameter that persistent with no concurrent uterine edema or signs of estrus

67
Q

how do you manipulate seasonality?

A

manipulate the photoperiod - mimic spring (need 16 hrs light and 8 hours dark) - add light at end of day, not beginning

68
Q

how long does it take to show effects when you manipulate photoperiod to change seasonality of mares?

A

6-8 weeks - then transition starts

we don’t skip transition!

69
Q

what is the classic program for manipulating seasonality?

A

begin artificial light Dec 1

70
Q

mare must be in ______ ____ when the mare and stallion are introduced to one another with natural service/live cover

A

standing heat

71
Q

warmbloods tend to develop ____ follicles.

A

larger

72
Q

fresh, cooled semen is viable for ____

A

48 hours

73
Q

oocytes are viable for ____ after ovulation

A

12 hours

74
Q

ideally, you breed ____ ____ ovulation

A

12 hours before

75
Q

sperm need about _____ to travel to the oviduct

A

6 hours

76
Q

for a 35mm follicle, you should use ___ to induce ovulation. for a 35-40mm follicle, you should use ___ to induce ovulation.

A

hCG
deslorelin

77
Q

tell me the timeline for using fresh cooled semen for AI

A
  • fresh cooled semen viable for 48 hours
  • shipment takes 24 hour
  • 35 mm follicle: hCG (takes 36 hours to induce ovulation)
  • 35-40mm follicle: deslorelin (takes 40 hours to induce ovulation)
  • inseminate 24 hours after administration of drug
  • ovulation 12 hours later
  • do post breeding US 24 hours later to confirm ovulation
78
Q

true or false: it is negligent to allow a mare to carry twins to term

A

true

79
Q

when is the earliest you can see an embryo on US?

A

12-14 days

80
Q

when is the ideal time to check for pregnancy on US? why?

A

16 days

egg is mobile at this time. if twins, you can separate eggs to horns and pinch one off

81
Q

what questions does the breeding soundness exam aim to answer?

A

what is the likelihood that this mare can:
- get pregnant
- maintain pregnancy
- what is the reason for infertility
- what is the reason for early embryonic death

should be discussed at EVERY pre-purchase exam on a mare, even if breeding isn’t the immediate goal for the horse

look at conformation!

82
Q

what are the components of the breeding soundness exam?

A
  • history
  • PE (general)
  • repro PE –> ideally during breeding szn (includes external genetalia, palpation of internal repro organs, endometrial cytology/culture)
  • vulvar conformation
  • palpation and US
  • vaginoscopy
  • uterine culture/cytology
83
Q

why do we look at vulvar conformation during the BSE? how do we fix poor conformation?

A

vulva provides the first effective barrier to protect the uterus from ascending infection

Caslick’s vulvoplasty

84
Q

the vaginoscopy during a BSE should be performed ____ (before/during/after) the palpation and US

A

after!

85
Q

what is the easiest and most common diagnostic performed in the field for repro exam? when is it performed usually in the mare’s cycle?

A

uterine culture and cytology

during estrus

86
Q

is the endometrial biopsy part of the normal BSE? what is it used for?

A

nope
used to investigate infertility when there’s early embryonic death or an inability to get pregnant

87
Q

where is an endometrial biopsy taken and when during the cycle?

A

taken during estrus (more accurately predicts fertility)
at the base of 1 horn

88
Q

infectious endometritis is more common in mares who _____

A

have poor vag conformation

89
Q

what are the clinical signs of infectious endometritis?

A

vaginal discharge, intrauterine fluid, infertility, early embryonic loss

90
Q

what pathogens are usually involved in infectious endometritis?

A
  • strep equi subsp. zooepidemicus (uterine specific strains)
  • E. coli (not uterine specific)
  • Klebsiella pneumoniae
  • Pseudomonas aeruginosa
  • yeasts and fungi
91
Q

how do you diagnose infectious endometritis?

A
  • endometrial cytology
  • culture and sensitivity
92
Q

based on endometrial cytology, when do you know it’s infectious endometritis?

A

when endometrial cells:neutrophil ratio is <40:1

93
Q

what is breeding induced endometritis?

A

physiological reaction to clear the uterine lumen - achieved through uterine contractions and the anti-inflammatory reaction

94
Q

what happens to normal mares who have breeding induced endometritis?

A

endometrial inflammation cleared within 24-36 hours

95
Q

what role do seminal plasma proteins play in breeding induced endometritis?

A

directing PMNs to dead spermatozoa

96
Q

what happens to “susceptible mares” who have breeding induced endometritis?

A
  • pathologic!
  • delayed clearance of breeding-induced inflammation with possible impaired uterine contractility
  • happens with frozen semen (low % of seminal plasma)
97
Q

how do you dx breeding-induced endometritis?

A

uterine fluid 24-36 hours post AI

98
Q

how do you treat breeding-induced endometritis?

A
  • uterine lavage (Ringer’s) –> “dilution is the solution to pollution”
  • oxytocin (wait 6h post AI)
  • PGF2 alpha - might impair CL development - be careful
99
Q

in the mare, does pyometra depend on the presence of a CL?

A

nope

100
Q

true or false: in mare pyometra, accumulated pus is sterile

A

true

101
Q

mare pyometra is often associated with ____. what is the most common cause?

A

cervical adhesions

poor cervical function is the most common cause

102
Q

how do you treat mare pyometra?

A

uterine drainage/lavage (repeated), surgery to address cervical issues

103
Q

what are these?

A

hemorrhagic follicles

they can be very painful!

104
Q

are mare anovulatory follicles cysts like in cattle?

A

nope

105
Q

what happens with anovulatory follicles in the mare?

A

initially, follicular development proceeds normally. then follicles “keep growing” and persists, and they persist for varying periods of time

106
Q

what is the most common ovarian tumor in the mare?

A

granulosa cell tumor

107
Q

granulosa cell tumors are ____ (malignancy) and ____ (uni/bi lateral) in the mare.

A

benign and unilateral

108
Q

true or false. granulosa cell tumors can develop during pregnancy in the mare

A

true

109
Q

what happens to the mare who has a granulosa cell tumor?

A
  • stallion-like behaviour
  • persistent estrus
  • inhibin increases - contralateral ovary small
  • increase testosterone
110
Q

how do you diagnose granulosa cell tumors in the mare?

A
  • US
    -GCT panel (testosterone, inhibin, and progesterone)
  • AMH
111
Q

what is the tx for a granulosa cell tumor in the mare?

A

sx

contralateral ovary resumes follicular activity on avg within 6 months

112
Q

you do US and see a suspected granulosa cell tumour. what are your ddx?

A

hematoma, cystadenoma, teratoma, dysgerminoma

113
Q

what are the clinical signs of an abnormal cervix?

A

infertility/subfertility

114
Q

what are 2 types of cervical abnormalities in the mare?

A
  • cervical adhesions
  • insufficient cervical closure
115
Q

cervical adhesions stem from ____ –> if severe, then ___ possible.

A

cervical lacerations (parturition)
pyometra possible

116
Q

infectious endometritis is often ____ (chronicity) and the result of unresolved ____.

A

chronic, PBIE

117
Q

what is pyometra?

A

large amount of pus and inflammatory debris in the uterus

end stage result of PBIE –> infectious endometritis –> pyometra

118
Q

how do you dx pyometra?

A
  • C/S are almost always absent!
  • US, culture
119
Q

ovulation failure typically results in a ___

A

lose of the cycle, may prevent return to heat, esp if partially luteinized

541 (sex class) (22 decks)

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