DVM Reproductive Medicine and Theriogenology 1

Question 1

In cattle, what is the average length of the estrous cycle?

Accepted Answer

21 days

Answer

The bovine estrous cycle averages 21 days (range 18–24 days), which is the standard interval used in synchronization and breeding management protocols.

Question 2

Which hormone is primarily responsible for luteolysis in most domestic species?

Accepted Answer

Prostaglandin F2α (PGF2α)

Answer

Prostaglandin F2α (PGF2α), produced by the endometrium, causes regression of the corpus luteum in most domestic species and is used clinically to synchronize estrus.

Question 3

The 'freemartin' condition in cattle occurs when:

Accepted Answer

A heifer born twin to a bull shares placental circulation, allowing masculinizing hormones to affect her reproductive tract

Answer

Freemartinism results from vascular anastomoses between bovine twins of different sexes, allowing Müllerian inhibiting substance and Y-bearing cells to masculinize the female twin's reproductive tract.

Question 4

In dogs, a primary reason bitches fail to conceive despite multiple breedings is:

Accepted Answer

Breeding at the wrong time relative to ovulation because canine oocytes require additional maturation time after ovulation

Answer

Canine oocytes are released immature at ovulation and require an additional 48–72 hours to become fertilizable; breeding must be timed precisely (typically 2–5 days post-LH surge) to achieve conception.

Question 5

After approximately day 150 of equine gestation, the primary source of progesterone maintaining pregnancy shifts to:

Accepted Answer

The fetoplacental unit

Answer

After day 150, the primary CL and accessory CLs regress in mares, and the fetoplacental unit assumes responsibility for progesterone production to maintain pregnancy through term.

DVM - Doctor of Veterinary Medicine Practice Test

DVM - Doctor of Veterinary Medicine Practice Test

DVM Reproductive Medicine and Theriogenology 1