Canine Estrous Cycle, Vaginal Cytology, Breeding Mgmt

Question 1

Puberty in dogs occurs ______

Answer 1

6-24 months (average age of 7-10 months)

- small dogs reach puberty earlier than big dogs

Question 2

Canine seasonality

Answer 2

Non-seasonal monoestrus

Question 3

What are the 4 stages of the estrous cycle?

Answer 3

• protestrus
• estrus
• diestrus
• anestrus

Question 4

What are the sources of reproductive hormones?

Answer 4

• estrogen: preovulatory follicle
• progesterone: CL and some from adrenal
• LH: pituitary
• FSH: pituitary
• GnRH: hypothalamus

Question 5

GnRH

Answer 5

Causes release of FSH and LH

Question 6

FSH

Answer 6

Stimulates preovulatory follicles

Question 7

LH

Answer 7

Causes ovulation

Question 8

Estrogen

Answer 8

initiates proestrus

Question 9

Progesterone

Answer 9

Maintains pregnancy

- there is no placental takeover of progesterone in dogs!!

Question 10

Behavioral changes

Answer 10

• attractiveness
• acceptance: when the female will stand for mating
• posture: rigid stance, deflects tail to one side, elevate vulva

Question 11

Physical changes

Answer 11

• color: pale (anestrus) to pink
• swelling: due to estrogen, causes Na retention in vulvar tissues
• discharge: serosanginous, blood comes from the wall of the uterus (diapedesis)

Question 12

Vaginal cytology

Answer 12

Percentage of cornification
- epithelial cells will cornify in response to high levels of estrogen –> are further from the blood supply due to swelling

Question 13

Endocrine level

Answer 13

Identify LH surge directly or indirectly

- most accurate staging method

Question 14

Proestrus

Answer 14

Bitch is attractive but not receptive

• vulva begins to swell and discharge starts
• vaginal cytology: intermediates, some cornified, RBCs
• basal progesterone, rising estrogen
• duration: 6-11 days (avg 9 days)!!!!

Question 15

Estrus

Answer 15

Bitch is attractive and receptive

• vulva is less turgid, straw colored discharged
• vaginal cytology: all cells are cornified (80-90%)
• progesterone rises from preovulatory lutenization, estrogen has peaked and is falling, LH surge
• duration: 3-20 days (avg 5-9 day)!!

Question 16

Diestrus

Answer 16

Bitch will no longer accept male

• vulva reduces in size and discharge stops
• vaginal cytology: intermediate, parabasal cells, lots of WBCs
• CL produces large amounts of progesterone
• duration: 57 days if pregnant, 60-100 days if not pregnant

Question 17

Anestrus

Answer 17

Period of sexual quiescence

• uterus is involuting and preparing for next cycle
• behavior similar to spayed female
• vaginal cytology: parabasal and intermediate
• progesterone and estrogen are both low
• duration: 2-9 months

Question 18

Proestrus averages ______

Answer 18

9 days

Question 19

Estrus averages _____

Answer 19

9 days

Question 20

LH surge triggers ovulation in ______

Answer 20

48 hours

- need to identify LH surge to determine when ovulation occurs

Question 21

Bitch ovulates primary oocytes over a period of _____

Answer 21

36 hours

- staggered release

Question 22

Each oocyte undergoes final phase of meiosis that takes ______

Answer 22

48 hours

Question 23

Eggs are fertilized in oviducts ______ after LH surge

Answer 23

4-5 days

Question 24

Fertilized eggs remain in oviduct for ______

Answer 24

8-10 days

Question 25

Embryos migrate to uterus by day ____

Answer 25

15 | - implantation occurs

Question 26

______ supports pregnancy throughout gestation

Answer 26

CL!

Question 27

If you want to prevent implantation right after an accidental breeding, than give ______

Answer 27

Estrogen! | - prevents embryo from reaching the uterus by tightening the utero-tubular junction

Question 28

Breeding management

Answer 28

- behavior of female - vaginal cytology - endocrine testing

Question 29

Vaginal cytology

Answer 29

Used to determine presence of estrogen - estrogen's effect on vaginal epithelium - cornified cells --> estrogen levels are or recently were elevated - parabasal cells: estrogen levels are low

Question 30

Vaginal cytology technique

Answer 30

- swab cranial vagina - roll on slide - stain with Diff-Quik

Question 31

What are limitations of vaginal cytology?

Answer 31

Used only to stage the estrous cycle

Question 32

Proestrus on cytology

Answer 32

Mixture of epithelial cells, some parabasal some intermediate - few superficial cells seen early, many seen late - RBCs seen throughout - percentage of cornified cells increases as proestrus progresses

Question 33

Estrus on cytology

Answer 33

Majority are cornified cells (90%), many anuclear - can see large numbers of bacteria - few RBCs or WBCs

Question 34

Diestrus on cytology

Answer 34

Abrupt return to parabasal and intermediate cells (occurs over 24 hours) - lots of WBCs - can see metestrum cells and foam cells

Question 35

Accuracy of timing depends on ______

Answer 35

Breeding situation - fresh semen can live in repro tract for 1 week - frozen semen will only live 12-18 hours

Question 36

Basics for the average bitch where live cover breeding will be supervised by the owner

Answer 36

Breed on 1st day of standing heat and every 2-3 days thereafter until bitch refuses mating

Question 37

If you are determining the fertile period, then breed _____

Answer 37

3-6 days after LH peak (1 day after ovulation)

Question 38

Progesterone testing

Answer 38

Progesterone levels will coincide with LH surge - RIA or in-house kit - should test every 2-3 days until ovulation is confirmed

Question 39

LH testing

Answer 39

Identify LH surge in serum sample - sendout or in-house kit (only gives positive/negative result) - must test often due to short duration of surge (18-24 hours)

Question 40

Progesterone values

Answer 40

- P4 rising through 2.0 coincides with LH surge - P4 between 4-6 coincides with ovulation - P4 greater than 10 coincides with fertile period - always assure animal has ovulated prior to breeding! LH surge --> ovulation --> fertile period

Question 41

Dogs will whelp ____

Answer 41

64-65 days from LH surge | - if you look at diestrus cytology, will whelp 57 days later