Canine Estrus Cycle

Question 1

Describe the physical changes during proestrus

Answer 1

• turgid swelling of vulva

- hemorrhagic vulvar discharge

Question 2

Describe the proestrus vaginal cytology

Answer 2

early - cornified epithelial cells, parabasal and small intermediate cells

late - superficial and large intermediate cells increase

Question 3

What is found on vaginal speculum during proestrus?

Answer 3

early - vaginal mucosa edematous

late - starts shrinking, less edema

Question 4

Describe behavior during proestrus

Answer 4

attracts males (sex pheromones) but non-receptive

Question 5

Describe the hormone profiles during proestrus

Answer 5

• estrogen dominates
• LH and FSH low
• progesterone low but rising

Question 6

What is the average duration for proestrus?

Answer 6

7-9 days

Question 7

Describe the physical changes during estrus

Answer 7

• softening of vulvar swelling

- scant blood discharge

Question 8

Describe the behavior during estrus

Answer 8

• stands to be mounted
• tail elevated and deviated to side
• muscles around vulva contract and raise vulva
• stiffening of back legs
• rolling of skin on back

Question 9

What is found on vaginal speculum during estrus?

Answer 9

early - shrinking of mucosa

late - max shrinkage called crenulation

Question 10

Describe estrus vaginal cytology

Answer 10

• > 90% cornified epithelium

- no WBCs, few RBCs

Question 11

Describe the hormone profiles during estrus

Answer 11

• estrogen begins to fall
• progesterone starts to rise
• high LH and FSH

Question 12

Describe the behavior during diestrus

Answer 12

female begins to refuse mating

Question 13

Describe diestrus vaginal cytology

Answer 13

• superficial cells decrease

- parabasal and small intermediate cells increase

Question 14

What is found on vaginal speculum during diestrus?

Answer 14

• rounding/smoothing mucosa

- may see variegated red/white areas

Question 15

What is the dominant hormone during diestrus?

Answer 15

progesterone

Question 16

Describe the behavior during anestrus

Answer 16

no sexual interest from male or female

Question 17

What is seen of vaginal speculum during anestrus?

Answer 17

vaginal wall is very thin and pale

Question 18

Describe anestrus vaginal cytology

Answer 18

• few non-cornified cells

- superficial cells absent

Question 19

When does LH peak?

Answer 19

24-48 hours into estrus

Question 20

When does ovulation occur?

Answer 20

24-48 hours after LH surge

day 3-4 of estrus

Question 21

LH surge occurs when progesterone is at what concentration?

Answer 21

2 ng/mL

Question 22

Ovulation occurs when progesterone is at what concentration?

Answer 22

5 ng/mL

Question 23

When should the bitch be bred naturally or with fresh semen AI?

Answer 23

48-72 hours after P4 concentration of 5

Question 24

When should the bitch be bred with cooled/chilled semen?

Answer 24

72-96 hours after P4 concentration of 5

Question 25

When should the bitch be bred with frozen semen?

Answer 25

at least 96 hours after P4 concentration of 5

Question 26

What is superfecundation?

Answer 26

when two males breed the same female during a single estrus

Question 27

What is superfetation?

Answer 27

where a female may be bred and pregnant, then go through another receptive period and get pregnant again