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Theriogenology > Reproductive Anatomy & Physiology of the Mare > Flashcards

Reproductive Anatomy & Physiology of the Mare Flashcards

1
Q

The cervix in the mare is approximately how long?

A

10-15 cm

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2
Q

What is the most sensitive organ to hormonal stimulation in the mare?

A

Cervix

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3
Q

The cervix in the mare is closed and dry under the influence of what hormone?

A

Progesterone

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4
Q

The cervix in the mare is low, relaxed and moist under the influence of what hormone?

A

Estrogen

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5
Q

Are ovaries located more laterally in the cow or mare?

A

Mare

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6
Q

What shape is the uterus of the mare?

A

Y or T shaped

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7
Q

What attaches the reproductive tract to the abdominal wall and may make the ovaries difficult to locate?

A

2 broad ligaments

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8
Q

The extensive mesovarium in a mare can mean what?

A

Wide variation in ovarian position

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9
Q

The uterus has about how many folds that run from the tip of the horns to the cervix?
What do these aid in?

A
  • 12-14 folds

- Fluid evacuation

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10
Q

What are 3 functions of the oviduct?

A
  • Sperm storage
  • Fertilization site
  • Embryo transport
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11
Q

Unfertilized ova are retained where?

A

Oviduct

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12
Q 
Fertilized ova (embryos) descend to where?
When?
A
  • Uterus

- 5.5 days after fertilization

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13
Q

The UTJ opens in response to what?

A

PGE

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14
Q

The ovaries in the mare tend to be around what vertebrae?

A

3rd or 4th lumbar vertebrae

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15
Q

Where is the site of ovulation on the ovary of a mare?

A

Ovulation fossa

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16
Q

Mature follicles are what size?

A

40+ mm

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17
Q

The further away from the ovulation fossa the oocyte is, the more dramatic the what?

A

Follicular change in shape (follicle oblongation)

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18
Q

The mare’s udder has how many halves?

Each half has how many glands?

A
  • 2 halves

- 2 glands

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19
Q

How many orifices are in each teat in the mare?

A

2

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20
Q

Regulation of the reproductive cycle of the mare is governed by what?

A

Hypothalamic-pituitary-gonadal axis

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21
Q

The majority of mares show signs of heat during what months?

A

May to August

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22
Q

Mares that have little to no ovarian activity and the uterus is flaccid with no tone are in what part of the cycle?

A

Anestrous

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23
Q

Short days stimulate what in the mare?

A

Stimulate the pineal gland to release melatonin that inhibits GnRH production.

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24
Q

How long is artificial lighting set for?

A

16 hours of light and 8 hours of dark

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25
Q

What size light bulb should be used for artificial lighting in a 12 x 12 stall?

A

200 watt

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26
Q

What is artificial lighting used for?

A

Advances transitional phase

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27
Q

What hormone can be used during seasonal anestrous to bring the mare out of anestrous?
What dose?

A
  • GnRH

- 20-25 ug TID IM for 2-3 weeks

28
Q

T/F: During the transitional phase, mares have multiple, variable size follicles.

29
Q

How does the uterus appear during the transitional phase in a mare?

A

Uterus has estrual tone with evidence of uterine edema.

30
Q

When does the transitional phase in a mare end?

A

With the first ovulation of the year.

31
Q

What dose of progesterone can be given to reduce the length of the transitional period in a mare?

A

150 mg IM SID for 10 days

32
Q

What dose of progestogens (Altrenogest) can be given to reduce the length of the transitional period in a mare?

A

0.044 mg/kg PO SID for 10 days

33
Q

What are 2 examples of dopamine antagonists that can be used to reduce the length of the transitional period in mares?

A
  • Domperidone (PO)

- Sulpiride (IM)

34
Q

Behavioral estrus is a result of estrogen acting on what receptors?

A

Alpha receptors of the brain

35
Q

T/F: The sensitivity of estrogen is the same between mares.

A

False - The sensitivity of estrogen is VARIABLE between mares.

36
Q

Is behavioral estrus a reliable breeding management tool to use in mares?

37
Q

During physiologic estrus, the mare is under the influence of what hormone?

38
Q

There is up regulation and activation of what type of receptors during physiologic estrus?

A

Follicular LH receptors

39
Q

Circulating estrogen levels are important for up regulation of what receptors?

A

Oxytocin receptors

40
Q

Physiologic estrus starts around what day if ovulation is day 0?

41
Q

What is the normal inter-ovulatory interval in a mare?

A

19-22 days

42
Q

What are 3 methods of estrus detection in the mare?

A
  • Teasing
  • Rectal palpation/vaginoscopy
  • US
43
Q

What are 4 observations made with rectal palpation/vaginoscopy during estrus?

A
  • Hyperemic moist elongated vulva
  • Soft cervix
  • Turgid uterus
  • Presence of a follicle
44
Q

What are 2 observations made using US during estrus?

A
  • Hyperplasia/edema of uterine folds

- Large dominant follicle

45
Q

At any stage during diestrus in the mare, an ovary may contain what?

A

Antral follicles of less than 2 to greater than 35 mm in diameter at different stages of growth and regression.

46
Q

The major primary wave starts with what?

Finishes with what?

A
  • Starts with uterine PGF

- Finishes with ovulation

47
Q

To distinguish between growing and regressing follicles of the ovulatory wave, what is necessary?

A

More than one US exam.

48
Q

What is a key component for proper breeding management?

A

Manipulation of the estrous cycle

49
Q

How large must a follicle be in order to be able to induce ovulation?

A

Greater than 35 mm

50
Q

What must be present in the uterus to induce ovulation?

What are 2 components of this?

A
  • Uterine edema

- Estrogen exposure and LH receptors

51
Q

When does ovulation usually occur once induced?

A

24-48 hours

52
Q

What are 4 examples of ovulation induction hormones?

A
  • Human chorionic gonadotropin (hCG)
  • Deslorelin injectable (Sucromate)
  • Deslorelin pellet (Ovuplant)
  • Recombinant LH (rLH)
53
Q

When does ovulation occur when induced by Ovuplant?

A

38-42 hours

54
Q

What is a drug that is very effective to induce ovulation in mares with good edema and a dominant follicle (35-42 mm)?

A

Ovuplant (Deslorelin)

55
Q

What is a good choice for ovulation induction with fixed time insemination programs with cooled and/or frozen semen?

A

Ovuplant (Deslorelin)

56
Q

What are 2 advantages of using Deslorelin vs hCG to induce ovulation in a mare?

A
  • Highly effective

- Wider window for treatment

57
Q

What are 3 possible causes of failure to respond to ovulatory inducing agents?

A
  • “Immature follicles” (not enough LH receptors)
  • Mare not in estrus even though large follicle is present
  • Anovulatory follicles (AHF)
58
Q

What are 4 criteria to determine whether or not a CL is present on US?

A
  • Diameter
  • Volume/area of the CL
  • Luteal tissue echogenicity
  • Doppler showing vascularization of CL
59
Q

T/F: The US appearance of the CL is a good indicator of its functionality and its age.

A

False - It is NOT a good indicator of functionality or age.

60
Q

What are 5 possible indications that an anovulatory follicle (AHF/HAF) is present?

A
  • Fails to ovulate in response to ovulatory inducing agents
  • Increases in size beyond normal
  • numerous free-floating echoic specks in the antrum
  • Single fibrin tags floating in FF
  • Organized fibrin in antrum
61
Q

What are 2 estrus induction agents that are luteolytic?

A
  • Prostaglandin F2 alpha (Lutalyse)

- Cloprostenol (Estrumate)

62
Q

When progesterone levels from to what level in what amount of time, this induces estrus?

A

Less than 1 ng/mL in about 24 hours

63
Q

A CL must be how many days old in order to be fully responsive to prostaglandin?

A

5 days old

64
Q

It is suggested to examine mares when in order to better predict the PGF response?

A

At the time of treatment.

65
Q

What are 2 things prostaglandins should not be used for?

A
  • Ovulation induction

- Uterine evacuation post-ovulation

66
Q

What are 4 other uses for progesterone?

A
  • Prolong luteal phase
  • Estrus suppression
  • Estrus synchronization
  • Pregnancy maintenance

Theriogenology (37 decks)

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