Canine Estrous Cycle & Breeding Management Flashcards
Taught by Dr. Chapwanya
What structure is present in the cranial vagina (before you get to the cervix) of the bitch that serves as an obstacle to insemination?
dorsal median vaginal fold
Occurrence of puberty is based on the ability of the hypothalamic neurons to produce sufficient ________
GnRH
T/F: Occurrence of puberty is typically ~6 to 10 months in all canine breeds
False
- 6-10 months in smaller breeds
- ~2 years for some larger breeds
- Variable in some breeds (English Setter 7-20 months)
T/F: Progesterone starts to climb at the beginning of proestrus in the bitch
False
Progesterone starts to climb at the beginning of estrus in the bitch
LH peak occurs between what two stages of the estrous cycle in the bitch?
proestrus and estrus
Ovulation occurs a few days later and fertilization occurs a few days after that
What is the average duration for proestrus and estrus in the bitch?
7-9 days each (14-18 days total)
However, each bitch is unique
What is the average duration of anestrus in the bitch?
90-150 days
(3-5 months)
The time from the beginning of one estrus to the beginning of the next estrus is termed:
interestrus period
Average duration is 7 months. Larger dogs tend to have shorter interestrus periods
T/F: Cornification of vaginal cells can be used to accurately predict time of receptivity, LH surge, and ovulation
False
Cornification of vaginal cells can not be used to accurately predict time of receptivity, LH surge, and ovulation. Period of maximum cornification varies between bitches
You introduce a cotton-tip swab into the caudal vagina of the bitch for vaginal cytology. You note blood on the swab. What stage of the estrous cycle is the bitch in?
Proestrus
What hormone predominates during proestrus?
Estrogen
This vaginal cytology is consistent with what stage of the estrous cycle in the bitch?
Proestrus
- Cornified epithelial cells increasing - “corn flakes” - large angular cells with small/no nuclei
- Red blood cells
- White blood cells - PMN’s - variable in number - decreasing in amount over time
- Debris in the background
Vaginal cytology of the bitch yielding greater than 90% superficial epithelial cells would be indiciative of:
estrus
- >90% Cornified superficial epithelial cells (squames), lots of anuclear squames
- One rule of thumb - 100% Cornified and 50% Anuclear
- No WBC’s – vaginal wall too thick to cross
- Few RBC’s
- Little or no debris in background of slide
- Sometimes see bacteria
- Cells may clump (“sheeting”) just prior to cytologic diestrus
During estrus in the bitch, the first sharp rise of progesterone is correlated with a peak in ________
LH
- Progesterone starts to rise during estrus. The initial rise coincides with the LH peak.
- Preovulatory rise is due to follicular estrual luteinization
- P4 starts to rise, when estrus ends, the P4 is already greatly elevated over baseline
The period in the estrous cycle of the bitch that is marked by a sharp decrease (50%) in the percentage of superficial cells and an increase in small intermediate and parabasal cells is:
diestrus
The female begins to refuse the male, although she may still be attractive to males. The uterus develops remarkable tone. Duration of diestrus is variable, but generally is 60 days (range of 45-90)
Maximum crenulation occurs during what stage of the estrous cycle in the bitch?
Estrus
Vaginal mucosal folds become progressively wrinkled (crenulated) in conjunction with ovulation and oocyte maturation.
In the bitch, a ________ oocyte is ovulated
primary
- In the bitch, a primary oocyte (2N) is ovulated (Prophase 1) and must go through further meiotic division to a secondary oocyte (1N) before the oocyte is ready for fertilization. This takes 2-3 days.*
- The secondary oocyte is then viable for 3-4 days (in general) and then become atretic if not fertilized*
Assessment of ________ is now the modern standard for assessing ovulation; assessing when to breed bitches
progesterone
-
Principle:
- 2 ng/ml = LH peak
- 5 ng/ml = Ovulation starting
- Confirm ovulation (>15 ng/ml)
- Ovulation - rise in P4 of 3 ng/ml in 24 h
Ovulation can be confirmed in the bitch by seeing a rise in P4 of ______ ng/mL in ______ hours
Ovulation can be confirmed in the bitch by seeing a rise in P4 of 3 ng/mL in 24 hours
Bitches should be bred _____ and _____ hours after P4 = 5ng (ovulation) for natural or shipped semen
Bitches should be bred 48 and 96 hours after P4 = 5ng (ovulation) for natural or shipped semen
(alternatively 24 and 72 h)
Bitches should be bred _____ hours after P4 = 5ng (ovulation) or higher for frozen semen
Bitches should be bred 72 hours after P4 = 5ng (ovulation) or higher for frozen semen
(Breed at 96 h with TCI and second dose of frozen semen)
T/F: Higher conception rates and larger litter sizes are observed with natural breeding than with artificial insemination in the bitch
True
LH assays are available as an in-house kit and are helpful in breeding management. Bitches should be bred _____ days after the LH peak
4-6 days
Canine oocytes are good for up to _____ hours post-ovulation
108 hours
-
Canine oocytes are good for up to 108 hours post-ovulation
- Could breed sometimes into diestrus with good results if you by-pass the closed cervix (ie surgical insemination or trans-cervical)
What structure in the dog’s external genitalia forms the “lock” during copulation?
bulbus glandis
When performing AI in a bitch with fresh semen, what is the minimum suggested breeding dose?
- 100 million motile sperm
- 200 million motile sperm
- 300 million motile sperm
- 500 million motile sperm
- 1 billion motile sperm
200 million motile sperm
Normal motility and morphology of spermatozoa in a normal stud dog should be greater than what, respectively?
- 50%, 80%
- 60%, 60%
- 80%, 80%
- 80%, 60%
- 50%, 50%
80%, 80%
When two males breed the same female during a single estrus, this is termed:
superfecundation
In Greek mythology, Heracles (Hercules) and his twin Iphicles are examples of heteropaternal superfecundation, with Heracles fathered by the god Zeus and Iphicles by a mortal man Amphitryon
Which of the following are used in chemical ejaculation of the dog?
- Oxytocin
- PGF2A
- hCG
- A and B only
- All of the above
A and B only
-
Oxytocin
- 5 IU subcuticular or intramuscular 5-10 minutes prior to manual stimulation
-
Prostaglandin F2α
- 0.1 mg/kg subcuticular or intramuscular 15 minutes prior to manual stimulation
The myofibril cells of the epididymal duct are smooth muscle cells- may respond to oxytocin and PGF2a
Which artificial insemination technique requires surgical intrauterine deposition of semen?
- Natural Service
- Fresh semen
- Fresh chilled
- Chilled Extended
- Cryopreserved
Cryopreserved
Surgery: midline laparotomy, small volume, 22 g needle (or catheter), place obliquely into lumen, visualize distention of uterine horn with injection to insure you are in lumen
When using cryopreserved semen to AI the bitch, she should be inseminated when (in relation to the LH surge)?
- 2 days prior
- On day of LH surge
- 1-2 days post LH surge
- 2-4 days post LH surge
- 5-6 days post LH surge
5-6 days post LH surge
What hormone in the bitch is measured as an indirect assay for LH?
progesterone
