Reproductive Anatomy and Physiology of the Mare

Question 1

Most sensitive organ to hormonal stimulation in mares?

Answer 1

Cervix.

Question 2

Cervix:

1. Average length in mares?
2. Closed and dry under the effect of what hormone?
3. low, relaxed, and moist under the effect of what hormone?

Answer 2

1. 10-15 cm
2. progesterone
3. estrogen.

Question 3

T/F: The cervix is ALWAYS dilatable in mare due to absence of fibrous rings

Answer 3

T

Question 4

Uterus Anatomy:

1. Shape?
2. Difference in ovary location compared to bovine?

Answer 4

1. Y or T shaped.

2. More lateral than cow

Question 5

Location and position of repro system in mares cna be affected by:

1.
2.
3.

Answer 5

1. distension/movement of intestines
2. distension/movement of bladder
3. pregnancy

Question 6

1. Describe how the repro tract is attached to the abdominal wall?
2. What side effect does this have on palpation?

Answer 6

1. two broad ligaments

2. may make ovaries difficult to locate

Question 7

T/F:

Extensive mesometrium means there is a wide variation in ovarian position

Answer 7

F, extensive mesoVARIUM

Question 8

1. Uterus has how __-___ folds.
2. Folds run from ___ to the ___
3. Purpose of the folds?

Answer 8

1. 12-14
2. tip of the horns to the cervix
3. aid in fluid evacuation

Question 9

Functions of oviduct in mare:

1.
2.
3.

Answer 9

1. Sperm storage
2. Fertilization site
3. Embryo transport

Question 10

1. Fertilized ova descends from the oviduct into the uterus how many days after fertilization?
2. UTJ opens in response to what?

Answer 10

1. 5.5 days after

2. PGE = SUPER IMPORTANT = PROSTAGLANDIN E

Question 11

Ovaries:

1. Location is variable, but usually close to ___
2. Site of ovulation?

Answer 11

1. 3rd/4th lumbar vertebrae

2. Ovulation fossa

Question 12

Ovaries:

1. Mature follicle is how large?
2. What determines the severity of follicular oblongation?

Answer 12

1. 40+ mm

2. the further the distance from the ovulation fossa

Question 13

Mare udder anatomy:

1. Teat distribution?
2. gland distribution

Answer 13

1. two halves with a teat each

2. each half has two glands with one orifice each

Question 14

Broad pathologic causes of anestrous:

1.
2.
3.
4.

Answer 14

1. Infectious
2. Lactational
3. Senile
4. Ovarian (endocrine)

Question 15

How is anestrus related to melatonin?

Answer 15

short days stimulate the pineal gland to release melatonin that inhibits GnRH production.

Question 16

Transitional Phase:

1. What do the follicle looks like?
2. What does the uterus look like?
3. Clinical Signs?
4. Ends when?

Answer 16

1. multiple variable size follicles, 20+ mm
2. Has tone and evidence of uterine edema
3. displays signs of estrus for variable lengths of time
4. Ends with the first ovulation of the year

Question 17

Methods to reduce the length of the transitional period:

1.
2.
3.
4.
5.

Answer 17

1. Progesterone - 150 mgs IM side for 10 days
2. Progestagens (altrenogest)
3. Dopamine antagonists to reduce dopamine levels in CSF
4. Domperidone
5. Sulpiride

Question 18

3 Methods of estrous detection:

1.
2.
3.

Answer 18

1. Teasing
2. Rectal Palpation / Vaginoscopy
3. U/S

Question 19

If you’re using Teasing for estrus detection, what signs would you expect if the mare was:

1. Not in heat?
2. In heat?

Answer 19

1. Aggressive kicking

2. Receptive winks, urinates

Question 20

What signs would indicate estrus during rectal palpation / vaginoscopy:

1.
2.
3.
4.

Answer 20

1. Hyperemic moist elongated vulva
2. Soft cervix
3. Turgid uterus
4. Presence of a follicle

Question 21

What would you see on U/S to diagnose estrus?

1.
2.

Answer 21

1. Hyperplasia/edema of uterine folds

2. Large dominant follicle

Question 22

At any stage during diestrus an ovary may contain _____ follicles of ____ - ____ size at different stages of growth and regression

Answer 22

antral

<2 to >35 mm

Question 23

1. Major primary follicle wave starts with what hormone?

2. Finishes with what process?

Answer 23

1. Uterine PGF

2. Ovulation

Question 24

Three goals during breeding season:

1.
2.
3.

Answer 24

1. Estrus induction
2. Ovulation induction
3. Prolong the luteal phase

Question 25

Natural processes that induce ovulation 1. 2.

Answer 25

1. Follicle size > 35 mm | 2. Uterine edema (estrogen exposure and LH receptors)

Question 26

Ovulation Induction Hormones: 1. 2. 3. 4.

Answer 26

1. hCG 2. Deslorelin injectable (sucromate) 3. Deslorelin pellet 4. Recombinant LH (rLH)

Question 27

Advantages of Deslorelin over hCG? 1. 2.

Answer 27

1. Highly effective | 2. Wider window for treatment

Question 28

U/S signs of ovulation: ``` 1. 2. 3. 4. 5. ```

Answer 28

1. Decreased turgidity 2. Loss of spherical shape 3. Apical area 4. Echoic spots in antrum 5. Serration of granulosa

Question 29

Two types of follicle evacuation with description: 1. 2.

Answer 29

1. Abrupt - 85% FF evacuates in < 1 min | 2. Gradual - 85% FF evacuated in 4-5 minutes

Question 30

T/F: The U/S appearance of the CL is a good indicator of it's functionality, but not it's age

Answer 30

F, it's not a good indicator ofeither

Question 31

4 Ways to determine you are looking at the CL on an U/S: 1. 2. 3. 4.

Answer 31

1. Diameter 2. Volume or area of the CL 3. Luteal tissue echogenicity 4. Doppler would indicate vascularization

Question 32

Possible causes of failure to respond to ovulatory inducing agents: 1. 2. 3.

Answer 32

1. Immature follicles = not enough LH receptors 2. Mares are not in estrus even though a large follicle is present 3. Anovulatory hemorrhagic follicles (AHF)

Question 33

Clinical signs that would indicate a HAF (hemorrhagic antral follicle) ``` 1. 2. 3. 4. 5. 6. ```

Answer 33

1. Fails to ovulate in response to ovulatory inducing agents 2. Increases in size beyond normal 3. Numerous free-floating echoic specks in the antrum 4. Single fibrin tags floating in FF 5. Organized fibrin in antrum 6. Interfere with cyclicity

Question 34

Luteolysis for estrus induction: Drug options: 1. 2. 3. Success confirmed via

Answer 34

1. PF2a (lutalyse) 2. Cloprostenol (estrumate) 3. Progesterone levels drop to basal < 1 ng/ml in 24 hours

Question 35

1. CL must be how old to be fully responsive to prostaglandin? 2. What can happen if you give luteolytic drugs daily for 3 days?

Answer 35

1. 5 days | 2. Anti-luteogenic effect

Question 36

Why is it recommended to examine mares at the time of treatment with luteolytic drugs?

Answer 36

To better predict the PGF response and because failure of this can result in undetected ovulations to further delaying the breeding

Question 37

Common WRONG ways to use prostaglandins: 1. 2. 3.

Answer 37

1. Ovulation induction 2. Uterine evacuation post-ovulation 3. Induction of Parturition