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)
How does endocrinology differ with bitches in anestrus? Behavior?
low estrogen and progesterone (<1 ng/mL)
no characteristic behavioral changes, but there is no sexual interest in males or females
What 3 clinical changes are seen with bitches in anestrus? How does the vaginal wall change?
- no characteristic changes
- no vaginal/vulvar edema
- no vaginal d/c
thin, pale pink mucosa
What are 2 characteristics of vaginal cytology with bitches in anestrus?
- scant numbers of parabasal and intermediate cells
- neutrophils and bacteria seen in low numbers
What do canine follicles do before ovulation? When are they able to be fertilized?
produce progesterone
primary oocyte ovulates and matures
What pregnancy recognition signal is there in canines?
none - not needed as the bitch will go through the same long diestrus period regardless of pregnancy status
- no known luteolytic PGF2a from uterus of non-pregnant bitches
What 4 hormone assays can be used to detect pregnancy in bitches?
- progesterone
- LH
- estrogen - direct measurements + use cytology to see effects
- relaxin
When is a deep vaginal culture indicated to determine pregnancy status?
prior fertility issues
How is a swab inserted to obtain vaginal cytology? What location is required?
begin perpendicular to the spine then progress horizontally
cranial vaginal vault —> caudal is thick and can look like estrus (high in superficial cells)
How does vaginal cytology change as a canine reaches estrus?
- normally thin - about 2-4 cell layers in anestrus
- in response to estrogen, cell layers thicken by the end of proestrus to protect the vagina against trauma
What does the cornification of vaginal cells imply? What can it NOT be used to predict?
if bitch is progressing and if she is in her fertile period (estrus = mostly cornified)
accurately predict time of receptivity, LH surge, or ovulation —> must coordinate cytology with hormone concentration and speculum examination
What are the 2 major reasons for performing a vaginoscopy?
- evaluate the effect of estrogen on vaginal epithelium
- evaluate vagina for sources of abnormal d/c or bleeding, masses, anatomical defects, or FB
What is the ideal equipment for vaginoscopy? What is an inexpensive option?
rigid cystoscope, pediatric proctoscope, or commercially available vaginoscope
otoscope or syringe casing —> can go through strictures without appreciating them (poor breeders fo unnoticed)
What infectious disease testing is necessary for canine breeding pairs?
Brucellosis —> diskospondylitis, life-threatening!
What are 5 requirements for AKC Breeder of Merit?
- history of at least 5 years involvement with AKC events
- earned AKC Conformation, Performance, or Companion event titles on a minimum of 4 dogs from AKC litters they bred/co-bred
- members of AKC club
- certifies that applicable health screens are performed on breeding stock as recommended by Parent Club
- demonstrates commitment to ensuring 100% of puppies produced are AKC registered
Is a pre-breeding vaginal culture required in healthy bitches? Why?
no, only indicated in presence of clinical disease
- not well correlated to uterine infection if present
- trans-cervical catheter commonly is contaminated with vaginal flora —> vagina is NOT sterile
What is the only bacterium definitively associated with infertility in canines?
Brucella canis
What equipment is used for vaginal cultures? What location is cultured? When is this done?
double-guarded cuturette, special media needed for Mycoplasma and Ureaplasma
near cervix
BEFORE other diagnostics to minimize contamination
How are dogs exposed to Brucella canis? When are males and females testes?
licking discharges
- MALES = prior to every breeding OR at least every 3-6 months as long as they are only exposed to negative bitches
- FEMALES = prior to every breeding
What Brucellosis testing is required for new additions to the kennel?
test/isolate/confirmed negative with retesting a month before introduction
What 6 tests are used for Brucellosis testing?
- Rapid Slide (Card) Agglutination Test (RSAT) - low incidence of false negatives, high incidence of false positives = good screening, 2ME-RSAT can interrupt false positives from antigen interaction
- tube agglutination
- IFA - antibodies or immune complexes in tissue/blood
- AGID - confirmatory to r/o false positives (cell surface vs cytoplasmic antigens)
- culture - definitive
- PCR - blood, vaginal/uterine swabs, semen, urine
How is ovulation timing done in cycling bitches?
- ID first day of vulvar swelling/discharge (this is Day 1)
- ovulation should start 3-4 days after proestrus starts or when vaginal certification is 60-75% so diagnostics blood work of progesterone and LH levels
- ID first day of standing estrus
What happens after the bitch ovulates primary oocytes?
- oocyte matures in 2 days (first polar body)
- matured oocytes survive for 3-4 days, then undergo atresia if not fertilized
- sperm must undergo capacitation ~7 hours/ovidcutal binding
What 3 things does ovulation timing frequency depend on?
- availability of stud/samples
- previous breeding/cycle history
- semen manipulations
What is the least accurate method of timing ovulation? What 4 methods are preferred?
behavior - bitch may ovulate anywhere from 2 days before to 6 days after onset of standing heat or estrus
- vaginal cytology
- vaginoscopy
- progesterone assay
- LH testing (expensive, easy to miss)
What is the most common strategy of breeding bitches based on behavior? What is success based on?
breed bitch every other day as long as she will stand and accept stud —> day 10, 12, 14, out of estrus by days 16-18
ability of fresh semen to live in female tract for 7-9 days —> higher conception rates and larger litter sized with natural breeding
(this is inappropriate for vets to use as the SOLE method of timing)
How are vaginal cytology and vaginoscopy used for timing ovulation? What ability does it have?
indirect measurement of estradiol (best used with progesterone testing)
poor correlation with ovulation day, but can be used retrospectively since ovulation occurs 5-7 days prior to the first day of cytological diestrus
+ whelping day will be 57 +/-1 day from first day of estrus
What is the modern standard for ovulation timing? What methods are preferred? How often are patients tested?
progesterone levels
quantitative RIA or chemiluminescence (semiquantitative in-house ELISA available, but not preferred)
every other day - initial rise coincides with LH peak
What changes in progesterone levels are seen as ovulation completes? When should bitches be bred based on these results?
- <0.5 = anestrus/early proestrus
- 0.5-1.9 = proestrus/early estrus
- 2.0-2.9 = day LH peak
- 3.0-3.9 = day before ovulation begins
- 4.0-10 = ovulation occurring
- > 10 = ovulation is complete
4 and 6 days after the LH peak with semen of excellent quality and appropriate quantity
When does LH peak? What causes this? How long does it take for ovulation to occur?
24-48 hours into estrus —> very short (12-24 hr) and must be assayed with in-house kits daily for detection (best used with progesterone levels)
estrogen peak and drop during proestrus
24-48 hr after LH surge (day 3-4 of estrus)
What is the average gestation length of canines?
65 days
What are the normal levels LH in spayed animals? What are LH assays most commonly used for diagnosing?
HIGH —> no negative feedback to hypothalamus due to estrogen normally produced by ovaries
when negative, gonadal tissue is present —> ovarian remnants, intact
What should occur following a positive LH assay in suspected neutered individuals? What confirmation is required?
double-check in 24 hours to ensure continued elevation to confirmed altered status
AMH —> prepubescent or time since neuter can alter findings
What is the 2:2:2:2 rule?
- when progesterone is 2 ng/mL, the LH surge has occurred
- bitch will ovulate 2 days later
- she should be bred 2 days after ovulation and again in another 2 days
How does the type of semen alter timing of breeding? How long will embryos remain in the oviduct?
- FROZEN = 72 hours after progesterone goes 5 ng or higher
- NATURAL/SHIPPED = 24-72 hours after progesterone goes 5 ng
9-10 days after ovulation, entering as a late morula or early blastocyst
What kind of semen has the best success? Where is it deposited? How much?
fresh
into the vagina, behind cervix —> hold hind end elevated for 10 mins
250 million motile sperm (normal morphology, forward progressive - NMFP)
What can aid some studs with poor quality semen? How much? What does this allow for?
uterine frozen insemination (consider poor quality as a hereditary issue)
use of lower insemination doses (100-150 million NMFP)
What method is preferred for AI in smaller dogs?
Norwegian/Scandanavian
small TCI catheter allows palpation of cervix and manipulation through folds
What equipment is used for surgical and trans-cervical insemination?
SURGICAL = laparotomy, laparoscopy, fresh/chilled/frozen semen; not commonly done due to welfare concerns
TCI = fresh/chilled/frozen semen, endoscopy, Norwegian catheter
