Sm An - The Estrous Cycle Flashcards
what are ovaries covered by
ovarian bursa
where is semen deposited
fornix
what is a pseudocervix
dorsal median fold of tissue between vaginal wall and cervix
how long does it take eggs to mature
48 hours on average
canine oocyte lifespan and breeding
Canine oocytes have longer lifespan → extends the breeding period but fertilization can only occur once
the oocytes are mature
when do progesterone levels start to rise
prior to ovulation
what can you use progesterone for
to determine when ovulation occurs
four stages of the canine estrus cycle
proestrus, estrus, diestrus, anestrus
what stages of the estrus cycle make up heat
proestrus and estrus
what is puberty
when the first proestrus occurs
can you breed on the first heat
NO
what is split heat
heat starts then stops without ovulation. Starts again later
what is silent heat
very little vaginal discharge.
when does puberty usually occur
Occurs earlier in small breeds vs. large breeds
◦ Average 8-14 months (range 6 – 26 months)
four methods to determine stage of estrus
-vaginoscopy
-vaginal cytology
-progesterone levels
-behaviour/receptivity
length of proestrus
9 days (0-27d range)
when is day 1 of heat
first drop of blood
what indicates estrogen levels are rising
Edema of vaginal epithelium; edema of the vulva
external cues of proestrus (3)
◦ Swollen vulva
◦ Serosanguineous vaginal discharge
◦ May start “flagging
state of progesterone during proestrus
Progesterone = low = baseline
behaviour of bitches during proestrus (3)
*Bitches are typically not receptive yet
*Bitches may mount other bitches
*Bitches in heat may become aggressive towards other bitche
what will you see on a vaginal cytology during proestrus
parabasal cells and intermediate cells
epithelium goes from 5-10 layers to 10-20 layers
length of estrus
9 days (4-24d range)
what happens during estrus
Stage at which LH surge occurs, ovulation occurs and fertile period occurs = when breeding occurs “standing heat”
estrogen levels and progesterone levels in estrus
-Estrogen levels elevated initially; peak; starts decreasing at LH
-Progesterone levels start to rise at LH, continue to elevate at ovulation & remain elevated
what can we use to estimate the LH surge
progesterone
when would we use an in house LH test
◦ Usually reserved for important breedings; frozen
semen breedings
when does LH surge occur
48hr before ovulation
what is crenulation
Edema of vaginal epithelium decreases
what happens to the vulva during estrus that we can see
Vulva becomes less turgid as estrogen decreases, serosanguineous discharge can diminish, can
become lighter
what behaviour will females do during estrus
Female should be receptive to male during fertile period
◦ Flagging
◦ Seeks out the male
what cells do you see in vaginal cytology during estrus
cornified epithelial cells
when do estrogen levels peak
estrus
length of diestrus
2 months (56-58 days if pregnant, 56-90 days if not pregnant)
will bitches be receptive to breeding during diestrus
no bc no longer in heat
when does diestrus occur
6 days after ovulation, or 8 days from the LH surge
what happens to the vulva during diestrus
Vulva diminishes in size, vaginal discharge subsides, vaginal epithelium flattens
levels of estrogen and progesterone during diestrus
Period of time when progesterone is high; estrogen is low
what do you see on vaginal cytology during diestrus
◦ Parabasal cells
◦ Intermediate cells
◦ Neutrophils
layers of vaginal epithelium during diestrus
2-4 cell layers
how do you tell the difference between proestrus and diestrus
progesterone levels!
length of anestrus
4 months (range 4-12 months)
when does anestrus occur
after diestrus
progesterone levels during anestrus
it drops! luteolysis
anestrus is a period of _____ ______
reproductive quiescence
what is anestrus an important stage for
Important stage for uterine involution
◦ Uterine involution is a necessary process
are bitches receptive to breeding during anestrus
no
what does the vulva look like during anestrus
vulva small, no vaginal discharge
why is a reproductive consultation important (2)
-Our responsibility to educate clients on responsible breeding
–>Time commitment
–>$$$
-Should only be breeding mature, healthy, good dogs
–>Clearances
–>Representative of the breed
what is included in breeding bitch management (4)
-hx (medical and reproductive)
-PE
-repro exam (digital palpation, vaginoscopy, vaginal swab for cytology)
-serum P4 levels (usually blood taken every 2 days)
what status do we need to know for breeding bitch managemnet
brucella canis status
breeding methods (4)
-natural
-vaginal AI
-transcervical insemination (semen deposited directly in uterus, can usually do without sedation)
-surgical insemination (semen deposited directly in the uterus, more invasive than TCAI
three types of semen that can be used in canine breeding
-fresh (can breed with standard vaginal AI, MAVIC catheter or TCAI)
-fresh chilled (semen collected, stored in cool place, shipped)
-frozen (TCAI or SAI only, progesterone timing required every 2 days, more in depth timing is required)
