The Stallion, Breeding Management, and Early Pregnancy Diagnosis

Question 1

How does seasonality affect the stallion?

Answer 1

No cessation in sperm production but lower sperm during short daylight
Reduced GnRH (lower LH, testosterone)

Question 2

Fresh Semen: Survival, Fertility, Temperature, Storage

Answer 2

Survival: 2 days
Fertility: best
Temperature: room/body
Storage: hours

Question 3

Cooled Semen: Survival, Fertility, Temperature, Storage

Answer 3

Survival: 1 day
Fertility: good
Temperature: 5C
Storage: day

Question 4

Frozen Semen: Survival, Fertility, Temperature, Storage

Answer 4

Survival: 12 hours
Fertility: variable
Temperature: liquid nitrogen
Storage: undetermined

Question 5

What is the criteria to induce ovulation?

Answer 5

35mm follicle
Endometrial edema
Estrus
Relaxed uterine tone
Open cervix

Question 6

What drugs can be used for the induction of ovulation? How long does it take for ovulation to occur?

Answer 6

hCG and/or GnRH analog
~1.5 to 5 days until ovulation

Question 7

How long does the equine oocyte remain viable after ovulation? How does this relate to when you want to breed her?

Answer 7

Equine oocyte will remain viable <12h after ovulation
Want to breed 6-8h after ovulation

Question 8

At what day can initial pregnancy detection/twin detection occur?

Answer 8

12-16

Question 9

At what day can a mare return to estrus?

Answer 9

16

Question 10

At what day of pregnancy can a heartbeat be detected?

Answer 10

25

Question 11

At what day of pregnancy do endometrial cups form?

Answer 11

35

Question 12

How long does it take for the equine embryo to enter the uterus?

Answer 12

5-6d after ovulation

Question 13

What what point can pregnancy be detected by palpation?

Answer 13

25 to 35 days

Question 14

What can be felt on palpation with pregnancy detection?

Answer 14

Ventral bulge at base of uterine horn

Question 15

Identify the structure

Answer 15

Embryo at 12d of pregnancy

Question 16

What occurs with maternal recognition of pregnancy?

Answer 16

Prevents release of prostaglandin and luteal regression
Until ~17-19d

Question 17

What occurs during the mobility phase?

Answer 17

Embryo round
Moves throughout uterus
Rapidly increases in size

Question 18

What occurs during embryo fixation?

Answer 18

Increased embryo size and uterine tone
Change in vesicle shape
Dorsal uterine hypertrophy
Remains “fixed” at base of uterine horn

Question 19

At what point can the embryo proper imaged?

Answer 19

Day 25
Indicator of viability, heartbeat

Question 20

What is secreted by the chorionic girdle?

Answer 20

eCG
PMSG

Question 21

Identify the structures

Answer 21

Question 22

Identify the structure

Answer 22