Canine Estrous Cycle, Vaginal Cytology, Endocrine Tests

Question 1

Timeline of events:

1. Puberty
2. Seasonality
3. Estrous cycle

Answer 1

1. 6-24 months, avg. is 7-10 months
2. Bitch is non-seasonal monoestrus
3. Divided into four stages (Proestrus, estrus, diestrus, anestrus)

Question 2

LH surge occurs between _____ and _____

Answer 2

proestrus and estrus

Question 3

increased ____ and fall of ____ causes ___ ___ to trigger ovulation

Answer 3

Progesterone; estrogen; LH surge

Question 4

What hormone is a source of preovulatory follicles?

Answer 4

Estrogen

Question 5

What hormone is a source of CL along with some adrenals?

Answer 5

Progesterone

Question 6

____ and ____ hormones source are pituitary

Answer 6

LH and FSH

Question 7

Hypothalamus produces this hormone–

Answer 7

GnRH

Question 8

Hormone actions:

1. what causes the release of LH and FSH?
2. What stimulates preovulatory follicles?
3. What initiates proestrus?
4. What maintains preg?
5. what causes ovulation?

Answer 8

1. GnRH
2. FSH from estrogen input
3. Estrogen
4. Progesterone
5. LH

Question 9

What is this stage:
Bitch is attractive but not receptive, vulva swelling and discharge, estrogen level is rising and progesterone level is low (basal)

Answer 9

Proestrus

Question 10

How long does the proestrus phase last?

Answer 10

6-11 days (avg. 9 days)

Question 11

What phase is this bitch:
Attractive and receptive, vulva is less swollen and discharge is straw colored, estrogen is peaks and progesterone is rising

Answer 11

Estrus

Question 12

How long does the estrus phase last? Why does vulva become less swollen than it was in proestrus?

Answer 12

Lasts 3-20 days (9 day average); because lower estrogen as compared to proestrus

Question 13

What phase is the bitch in:

Not accepting males, vulva shrinks in size, no discharge, CL begins to produce large amounts of progesterone

Answer 13

Diestrus

Question 14

How long does the diestrus phase last?

Answer 14

57 days if pregnant, if NOT pregnant, then lasts 45-75 days

Question 15

______ is a period of uterine involution and prepares for the next cycle. Behavior will be similar to spayed female

Answer 15

Anestrus

Question 16

Progesterone and estrogen are both low in what phase?

Answer 16

Anestrus

Question 17

How long does anestrus last?

Answer 17

2-9 months

Question 18

1. Proestrus averages ___ days
2. Estrus averages ___ days
3. ____ ____ triggers ovulation in ___ hours

Answer 18

1. 9
2. 9
3. LH surge; 48 hours

Question 19

Bitch ovulates primary oocytes over a period of ___ hours, each oocyte undergoes a final phase of meiosis that takes ___ hours

Answer 19

48 hours; 48 hours

Question 20

Eggs are fertilized in the oviducts in __-__ days after LH Surge and they remain in the ovaduct for __-___ days

Answer 20

4-5 days; 8-10 days

Question 21

Fertilized eggs remain in the ovaduct for __-___ days. Embryos migrate to the uterus by day ____ and implantation occurs.

Answer 21

8-10 days; day 15

Question 22

What structure supports pregnancy all throughout gestation?

Answer 22

CL

Question 23

Cornified cells on vaginal cytology means ___ levels are (or were recently) elevated

Answer 23

Estrogen

Question 24

_____ cells indicate estrogen levels are low

Answer 24

Parabasal

Question 25

Where do we swab for a vaginal cytology?

Answer 25

Cranial vagina

Question 26

What cells will we see in a vaginal cytology of a bitch in proestrus?

Answer 26

Some parabasal cells and some cornified cells increased and proestrus progresses into estrus. May also see RBCs and superficial cells

Question 27

Estrus- majority of the cells are _____ and anuclear. Some bacteria may also be seen.

Answer 27

cornified,

Question 28

Abrupt return to parabasal and intermediate cells with lots of WBCs, metestrum cell, and foam cells seen tell us we are in what stage?

Answer 28

Diestrus

Question 29

Progesterone testing of a bitch: what does each P4 coincide with??

Answer 29

P4 rising through 2.0 coincides with LH surge
P4 between 4-5 coincides with ovulation
P4 > 10 coincides with fertile period

Question 30

LH surge–_____–_____ _____

Answer 30

LH surge- ovulation- fertile period

Question 31

How long is the time between LH surge and fertile period (between ovulation)?

Answer 31

Two days

Question 32

When should we breed bitch?

Answer 32

Breed 3-6 days after LH peak