Canine Estrous Cycle/ Breeding Managment Flashcards
When do dogs reach puberty?
6-10 months in small breeds
Can be up to 2yrs in large breed (eg Great Dane)
When do dogs have maximum reproductive capability?
At 2-4th estrus (about 3 years of life)
What is a splint/false heat?
Exhibit sings of proestrus (bleeding), but estrus may not occur immediately afterwards (may be days to weeks)
What is a silent heat?
Ovulation occurs in absence of proestrus-estrus behaviour/signs
What type of estrous cycle does the canine have ?
Monoestrus (1-2 cycles per year)
Non-seasonal usually
Length of anestrus in canine?
5months
Length of proestrus in canine
9d
Length of estrus in canine?
9 days
Length of diestrus in canine
2 months
What is the interestrus period?
Time from the beginning of one estrus to the beginning of the next estrus
Average 7 months (range 4-12months)
Larger dogs tend to have shorter interestrus periods
What is the minimal intraestrus period?
4 months
—> fertility will be low if 90 days in anestrus is not achieved
Desqumation and repair period necessary after prolonged canine luteal phase
What breeds are predisposed to shorter interestrus periods?
Rottweiler
German shepherd
What is the response of the vaginal epithelial to estrogen?
Increase thickest
2-4 layers thick in anestrus —> 20-40 layers thick by end of proestrus
Protects vagina against trauma and prevents bacterial entry
T/F: cornification of vaginal epithelium can accurately predict time of receptivity, LH surge, or ovulation
False
— period of maximum cornification varies between bitches
How can receptivity, LH surge, or ovulation be accurately predicted?
Coordinated cytology with hormone concentrations and speculum examination
What type of cells do you see during proestrus?
Early — mostly parabasal, small and large intermediate cells
Late — mostly superficial cells. The edges are straight and the edges are flattened
What type of cells do you see in estrus?
Fully cornified
What type of cells do you see during diestrus?
Mostly parabasal cells, mostly non cornified
What are signs of proestrus?
Turgid swelling of vulva
Hemorrhagic vulvar discharge
Attracting males but non-receptive
- early will grow/snap, show aggression
- late will be passive, tuck tail and sit down when male attempts to mount
Edematous vaginal mucosa
What is the dominant hormone in proestrus?
Estrogen
What stage is this?
“Corn flake” cells —> cornified epithelium with large anuclear cells
RBC
WBC present
Debris in background
Proestrus
What stage is this ?
Estrogen dominates
LH and FSH low
Progesterone low
Proestrus
Signs of estrus?
Softening of vulvar swelling, scant blood discharge
Shrinking of vaginal mucosa
Max shrinkage called crenellations
Angled mucosa
Stands to be mounted a bred
- tail to the side and elevated
- vulva raises
- stiffening of back legs
- rolling of skin on back
What stage is this?
Increasing progesterone
Estrogen falling
LH and FSH peaks
Estrus
What stage is this?
> 90% cornified superficial epithelial cells
Anuclear
No WBC
Few RBC
Little to no debris in background
The first sharp fries of P4 is correlated with?
LH peak
Preovulatory rise is progesterone is due to ?
Follicular estrus luteinization
What stage is this?
Non acceptance of mating
Round/smooth vaginal mucosa
Cytology shows parabasal and small intermediate cells
Diestrus (pregnancy or pseudo pregnancy)
What hormone is associated with mammary development ?
Prolactin
How does diestrus end?
Luteolytic PGF2a from the uterus
Signs of anestrus?
So sexual interest from male to female or vice versa
Vulva not swollen
Both non cornified and cornified cellls
Neutrophils and bacteria may be present
Thin vagina wall, appears pale
Progesterone is baseline
How many days after the beginning of proestrus do you want to begin diagnostic blood work?
3-4days
Estrogen peaks during ______ and LH peaks during _____
Proestrus; estrus (1-2days into estrus)
When does ovulation occur relative to the H surge?
24-48hrs after the LH surge
Ovulation takes about 24hrs to complete
After the secondary oocyte is produced, it is viable for _____ days. If it is not fertilized in this time it will become atretic.
3-4
What is the standard test for breeding managment?
Progesterone P4
Sample every other day
Can be done by ELISA, RIA or chemoluminescense
What progesterone level coincides with LH peak?
2ngml
What progesterone level coincides with the start of ovulation?
5ng/ml
Ovulating up to 8ng/ml
At what level of progesterone is ovulation complete?
15 NG/ml
At what level of progesterone does natural mating occur or fresh semen AI can be sued?
8.7 - 13.1
28-72 hours after ovulation starts (P4=5ng/ml)
Cooled/chilled semen AI can be done when progesterone levels are _____
14.2
About 72-96 hours after ovulation starts, or 5ng/ml progesterone level
Frozen semen AI can be done when progesterone level is _____
19.3-21.6
About 96hr after ovulation starts, or 5ng/ml progesterone
How long does a fertilized embryo stay in the oviduct before entering the uterus?
9-10days (enters uterus as late morula or early blastocyst)
LH assays are more definitive than progesterone, but what are the disadvantages ?
Must take daily blood samples
Spayed animals will have high LH because they have no negative feedback
How many days post LH peak should you need your dog?
2-3days
How many progressively motile sperm should the fertile male have?
200 x 10^6
Should have 80% normal morphology and 80% motility
What are you evaluating for breeding soundness in the dog?
Scrotal measurements
—> normal
Log scrotal width = 0.324(log BWt)+1.249
Symmetry
— asymmetry may be indicative of testicular pathology such as degeneration or inflammation
Methods of semen collection in the dog?
Manual stimulation (most common)
Chemical ejaculation (used in conjunction with manual stimulation, may increase sperm numbers))
Electroejaculation
Requires GA
Where do the fractions of sperm come from?
Prostate, epididymis, prostate
What is used for chemical ejaculation?
Oxytocin — 5IU SQ or IM 5-10mins prior to manual stim
Prostaglandin F2a —0.1 mg/kg SQ or IM 15min prior to manual stim
What is normal concentration, total amount, and motility of sperm?
Concentration: 4-400 x 10^6/ml
Total sperm: 300-2,000 X10^6 / ml
Motility: at least 80% progressive
If you are using frozen semen, what method of AI must you use?
Transcervical or surgical —> semen must go into uterus
Surgery: midline laparotomy, small ovules 22g needle into lumen
What are reasons that breeding might not occur?
Female in proestrus
Vaginal anomaly
Arthritis in male— painful breeding
Prostatic pain in male
Penile issue
Breed
Uncooperative dogs
T/F: vaginal strictures or bands are heritable and these dogs should not be bred.
False
Developmental defect
Can be bred, require AI, C section
Removal of bands
What do you call when two males breed the same female during a single estrus?
Superfecundation
What do you call a female that breeds and gets pregnant and then goes through another receptive period and gets pregnant again (will have fetuses of different ages)
Superfetation
NOT in dog.
Can occur in mice and rats
