Canine reproduction Flashcards
monoestrous
one estrous cycle per year
domestic dogs= not seasonal
depending on length of anestrus can cycle twice a year but still considered monstrous
bitch
intact female
dog
intact (stud) dog
Heat
combo of estrus and proestrus
time when vulvar discharge seen
puberty
onset of first estrous cycle
6 mo. to 2 years of age
small vs. large bitches cause variation
interestrus interval
time between proestrus and the next
4.5-12 months so why can cycle 2 times a year
german shepard- shorter
besenji- longer (yearly estrus)
stages of estrous cycle
day 0= ovulation high E2 low progesterone
metestrus= short in dog
long diestrus with high progesterone followed by anestrus, proestrus and estrus
follicular phase
estrogen from ovarian follicles
subdivided into proestrus and estrus
luteal phase
dominated by progesterone
in bitch, not generally subdivided into metestrus and diestrus
canine estrous cycle
proestrus
estrus
diestrus (canine diestrus is european metestrus) =progesterone dominance
anestrus- rest
anatomy
female from paramesonephric mullerian duct (male= wolfian)
in area near vestibule formed from 3 different embryonic tissues
cervix- open at estrus (contrast only passes in proestrus and estrus
canine estrous cycle
behavior
vaginal cytology
endocrinology= gold standard in dog
anatomy
events= interrelated, but much variability exists between animals and even between cycles
vaginal cytology
gives basic idea of where bitch is in the estrous cycle
useful if used in conjunction with progesterone
bioassay for presence of estrogen
non cornified epithelial cells
parabasal and intermediate cells
start getting signs of cell death under estrogen begin to cornily- keratinize
cornified epithelial cells
superficial
anuclear squamous
dead cells
cornification
shows the progression of epithelial cell death resulting from tissue thickening due to estrogen
vaginal cytology cells
parabasal cells- sunny side up, when not in heat (anestrus)
intermediate cells- over easy, unhealthy cytoplasm
superficial cells- pyknotic nucleus, unhealthy cytoplasm and nucleus
anuclear squamous- cornified
vaginal cytology progression
proestrus- paranasal cells (not fortified), early on can have neutrophils
between proestrus and estrus= intermediate
late proestrus= no neutrophils
estrus- superficial cells, cornified
Diestrus- early= PMNs (neutrophils) and then intermediate present
anestrus= basal, neutrophils mainly
vaginoscopy
can look at epithelium
hormones
LH- ovulation
estrogen- vaginal lining epithelial cells and wall thickness, behavior and physical signs (standing heat)
progesterone- produced in pregnant and non pregnant bitches, if increase doesn’t mean pregnant
relaxin- blood pregnancy test for dogs and cats
produced by canine placenta, relaxes pelvic canal and cervix
Luteinizing hormone
LH
LH peak lasts for up to 2 days in dogs
very definitive event in estrus cycle because of this use this peak as day 0
progesterone
P4
test used to find out when fertile from breeding management standpoint
quantitative laboratory determination more accurate than dog-side qualitative test
Proestrus
0-27 days, average 9 days
behavior= attractive to the male, but not receptive- will not stand to be bred
vaginal cytology= progressive cornification (estrogen increasing)
endocrinology- estrogen rising to peak, pre-ovulatory rise in progesterone (pre ovulatory luteinization)
anatomy= vulvar swelling and serosanguinous discharge; vaginal fold thickening; follicular development
source of RBC is uterine diapedesis
early proestrus
normal presence of non-degenerate neutrophils
late proestrus
more cornified
proestrus vaginoscopy
very pink, pillowy folds that are glistening
signs of proestrus
vulvar swelling and discharge, flagging
Estrus
length= 4-24 days, average 9 days
behavior= receptive, stands to be bred
vaginal cytology= cornification prominent (no WBC)
endocrinology= estrogen falling (continue to cornify), preovulatory rise in progesterone continues and LH peak
anatomy= less vulvar swelling and serous to serosanguinous discharge; vaginal fold crenulation; further follicular development and ovulation
cornification
vaginoscopy= not pillowy and pink, crenulation, more space
estrus in bitch= different
progesterone rising in pre-ovulatory
as in other species, continues post-ovulatory as the CL develop
estrogen falling
estrus length and definition
LH peak= defining moment
abrupt and short
less than 24 hours, occasionally 48 hrs
ovulation occurs 24-48 hrs later, signal for ovulation to occur (LH peak)
hormone levels
LH peak at day 0
progesterone starts to rise post LH peak
estrogen peak= pre ovulation
progesterone concentration
10 ng/ml = already ovulated
how many days post LH surge is bitch most fertile
4-6 days
because takes 1 to 2 days to ovulate and bitch ovulates
primary oocytes that can’t be fertilized so need 1-2 days to mature 4-6 days
ovulation
bitch= different
ovulates primary oocytes
then must then mature with meiosis to secondary oocyte prior to fertilization
first division in meiosis is reductional
maturation takes 24-48h, by 3-4 days post LH
breed 4-6 days after the LH peak for optimal results- times for mature oocytes
ovulation
prior to LH surge= progesterone increases
day 0= LH surge
day 1= ovulation
sperm capable of fertilizing for at least 4-6 days so can arrive at oviduct around 10 days
when ovulate it is a primary oocyte which requires 24-48 hrs capacitation
day 89= cytological diestrus- when out of heat
Diestrus
behavior- not receptive
vaginal cytology- abrupt change to non-cornification; WBC normal
endocrinology- high progesterone
anatomy- less vulvar swelling; discharge quality variable, then stops; vaginal fold thinning, CL
Diestrus cytology
normal appearance of neutrophils
Anestrus
length= 4.5 to 5 mo. (minimum 7 weeks after P4 falls below 1-2 ng/ml)
behavior- not receptive, not attractive to the dog
vaginal cytology- not cornified
endocrinology- no progesterone or estrogen, late (before pro estrus) some LH, FSH and estrogen
anatomy- no vulvar swelling; no discharge; vaginal folds thin; inactive ovaries
Hormone concentrations
Anestrus 5 mo.= high but steady FSH, LH low but peaks prior to proestrus, E2 increases mid cycle
Proestrus 9 d= FSH decreases, E2 increases nearing day 0 as does LH for LH peak
estrus 9 d= FSH, LH and E2 all decrease ovulation complete (day 3), fertilization complete (day 6)
diestrus 2 mo. (luteal phase) = decrease E2 and LH low but slight fluctuations
progesterone= low during proestrus, estrus increases and peak early in diestrus
Mating
first stage coitus, then turn before 2nd stage coitus
pregnancy
progesterone high in diestrus, irrespective of pregnancy status
cannot be used as pregnancy test
CL dependent to turn
Endotheliochorial, zonary and deciduate
only 1 zone of attachment to uterus
marginal hematomas- green pigment uteroverdin, if during pregnancy means loosing attachment and bad
canine pregnancy dx
ultrasound- day 20 to term
palpation- day 22 to 28
relaxin- day 22 to term (best > 28)
radiographs- day 42 to term (better later)
parturition
mechanism similar to ruminant- cortisol, PGF, oxytocin
CL dependent to term
thing 65 +/- days post LH peak (very tight bell curve) 57 +/- days post diestrus cytology 57-72 days from 1 breeding within 1 day- body temp falls to 99F
stage I- preparation
variable timing
nesting, poor appetite
cervical softening
green discharge
Stage II- fetal expulsion
contractions
duration variable
generally half to 1 hour between pups
licks neonate
prolonged uteroverdin discharge without birth of pup indicates placental separation and thus fetal life at risk
Stage III
fetal membrane passage, generally with each pup
bitch may eat membranes
Puerperium
involution- prolonged, minimum 2 months
lochia- variable often brick-red brown, several weeks, odorless
Pseudocyesis
pseudoprengnancy normal- every nonpregnant diestrus progesterone fall stimulates prolactin rise prolactin instrumental in lactation overt vs. covert iatrogenic- OHE during diestrus
summary
normal canine estrous cycle- several major difference from other domestic animals
normal pregnancy
