Canine Female Reproduction Flashcards
What are proper reasons to breed a pet?
- good representation of the breed - temperament, structure
- healthy both physically and mentally
- interest in furthering the breed by producing quality (NOT QUANTITY) pets for companionship, working, or showing
- NOT for money-making enterprises
- able to financially and mentally prepare for all that can go wrong
- prepared to assume responsibility for puppies for life
Canine reproductive anatomy:
What are the 5 origins of reproductive hormones in female canines?
- hypothalamus - GnRH
- pituitary - LH, FSH, prolactin, oxytocin
- ovaries - estrogen, progesterone, inhibin, oxytocin, relaxin
- uterus - prostaglandin
- placenta - relaxin
What is the average onset of puberty in female dogs? What does this depend on?
10-12 months
breed-dependent - larger dogs reach puberty later
What is the first estrus in bitches like? What 2 things are commonly seen? How does this affect breeding timing?
IRREGULAR - don’t judge fertility yet
- split heat - exhibit proestrus, but don’t ovulate
- silent heat - pubertal bitches are less likely to demonstrate estrus when ovulation occurs
not recommended to breed on first heat —> require sexual and emotional maturity
What kinds of dogs typically have later onset of first estrus? What can hasten estrus induction?
working lines - field retrievers and pointers
housing with other cycling bitches (medical induction not successful)
What is the interestrus period? What is the average duration? What is the minimum cycle length?
time from the beginning of one estrus to the beginning of the next estrus
7 months - longer in older dogs >8 y/o
4 months - fertility will be low if at least 90 days is not reached
What is required after a prolonged luteal phase? What is the maximum length of the canine reproductive cycle?
desquamation and repair
12 months - any longer = investigation indicated
What kind of estrous cycle do canines have? When do they typically reach the peak?
non-seasonal, monestrus —> 1-2 cycles/year with litters born year-round (environment can affect)
late winter to spring (Feb-May)
What are the 4 stages of the canine reproductive cycle?
- proestrus - initiation of overt activity
- estrus - time for breeding
- diestrus (metestrus) - pregnancy or pseudopregnancy
- anestrus - quiescence and repair
What is the average duration of proestrus? What stage is it considered?
9 days (ranges 2-25 days, remain flexible)
follicular - estradiol rises in early proestrus and peaks at the end, progesterone and LH are low
What behavior is seen in bitches in proestrus? What 2 clinical signs are seen?
males are attracted to female, but she will not accept mating, tucks tail, sits, and turns to fend off
- swollen, edematous, and firm vulva
- bloody vaginal discharge
(typical first signs of heat)
What causes change in the vaginal wall during proestrus? What 3 things are seen?
high estrogen
- light pink, shiny, and edematous mucosa
- vaginal epithelium proliferates (wall thickness)
- diapedesis of erythrocytes
What 4 vaginal cytological changes are seen during proestrus?
- mixed cells - intermediate and superficial with progression to more superficial as it estrus approaches
- large numbers of RBCs
- normal bacterial flora (subclinical UTIs common)
- variable WBCs decreasing in amount over time
What is the average duration of estrus? What 2 hormone changes are seen? When does ovulation occur?
9 days (range 3-21)
- estradiol begins to decrease
- progesterone rises prior to forming CL
LH surge as once progesterone reaches 2 ng/mL —> primary oocyte released in 2 days —> oocyte needs 2 days to mature to allow fertilization (222 rule)
When should a bitch be bred?
4-6 days after the initial LH surge
What behavior is seen with bitches in estrus? What are the 2 most common clinical signs?
winking, leaning, flagging, and standing to be bred
- edematous and firm vulva begins to soften
- vaginal d/c becomes more serosanguinous (pink)
What 3 changes in vaginal cytology are seen with bitches in estrus? What is the limitation to seeing these changes?
- 100% cornified cells with about half nuclear sheets
- fewer RBCs and bacteria
- no WBC - vaginal walls too thick to cross (if they are present, it can indicate infection/inflammation)
CANNOT be used to predict ovulation time prospectively
How does the vaginal wall of bitches in estrus look?
thick, drier, wrinkled (crenulated), pale to white in color
How long does diestrus last in pregnant and non-pregnant bitches?
55-60 days
45-90 days
What change in hormones is seen in diestrus? What 5 things does this result in?
progesterone dominance - peaks within 3 weeks
- hypertrophy and hyperplasia of uterine glands
- cervix constricts
- vaginal secretions become mucoid
- uterus becomes more flaccid
- prolactin production
What time period does ovulation and whelping occur in relation with diestrus? When does diestrus end?
- OVULATION = 5-7 days before 1st day of diestrus
- WHELPING = 57 +/- 1 day from onset of 1st day of diestrus
when progesterone drops below 2 ng/mL
What 2 changes in vaginal cytology are seen in diestrus?
- sharp decline in superficial cells and sudden appearance of white blood cells
- reappearance of intermediate and parabasal cells
What 3 physical changes are seen with bitches in diestrus?
- vaginal wall becomes thinner
- vaginal wall appears pink and moist, but not edematous
- mammary development (subtle in non-pregnant bitches, reflecting prolactin levels)
What is the average duration of anestrus in bitches? Why is this timing required?
4.5 months —> prolonged period of sexual rest
endometrial repair (120-150 days)