The Whelping Box —
Managing the Prospective Mom
By Carolyn Russell Gold
Responsible breeding involves much preparation beforehand, including careful research and self-education by the breeder as well as ensuring that the bitch is healthy and ready for breeding. The following information on preparing the bitch for breeding is based on interviews with and information drawn from articles provided by Autumn Davidson, DVM, MS, Dipl. ACVIM, VMTH SAC, of the School of Veterinary Medicine at the University of California, Davis. Dr. Davidson kindly responded to the following questions about the bitch’s reproductive cycle and managing the prospective dam.
Q: How does a breeder begin breeding management of the female prior to breeding?
A: The canine estrous cycle consists of four phases: proestrus, estrus, diestrus, and anestrus. Proestrus and estrus are commonly called “heat” or “season.” During proestrus, the start of the estrous cycle, the female attracts male dogs but is still not receptive to breeding.
Q: What happens next?
A: The female may become playful or passive as proestrus continues. A blood-tinged vaginal discharge (of uterine origin) is present; the vulva is moderately enlarged and turgid. Cells from vaginal cytology smears change over a period of four to seven days from non-cornified (small “parabasal” cells and small and large “intermediate” cells) to cornified cells (“superficial-intermediate” cells and
Q: What do these changes in vaginal cytology mean or signal to the breeder?
A: These changes reflect increasing estrogen from the ovarian follicles. Red blood cells are usually, but not invariably, present. Proestrus can last from three days to three weeks, with nine days the average. Proestrus progresses to estrus.
Q: What happens during estrus?
The normal female displays receptive (or sometimes, passive) behavior, enabling breeding to occur. Vaginal discharge normally diminishes at this time, and it may become lighter in color or even be clear. Vulvar edema tends to be maximal and the vulva flaccid to facilitate breeding. Vaginal cytology during estrus consists of 80 to 100 percent cornified cells. Red blood cells tend to diminish but sometimes persist throughout estrus.
Q: How long does estrus normally last?
Estrus can last three days to three weeks, with nine days being the average. Receptive behavior begins when estrogen concentrations decline and progesterone concentrations increase. The duration of receptivity to male dogs is variable and may not coincide precisely with the fertile period, which occurs during estrus.
Q: When does ovulation occur?
A: Ovulation is triggered by a surge in the luteinizing hormone (LH) produced by the pituitary gland. Ovulation of immature, infertile primary oocytes (eggs) begins approximately two days after the LH surge; oocyte maturation occurs over the following one to three days. The life span of the secondary (fertile) oocytes is two to three days. The female’s actual fertile period extends from three through six to seven days after the LH surge. The LH surge occurs at the same time as an initial increase in progesterone concentration, enabling ovulation timing by measurement of either hormone.
Q: How does the breeder time ovulation?
A: Ovulation timing should be performed using a combination of serial vaginal cytologic exams, ideally serum (blood) progesterone concentrations. Testing for LH can be used in some cases (such as for infertility or frozen-semen breedings).
Start vaginal cytology exams during the first few days of proestrus; perform every two to three days. When more than 70 percent of the epithelial cells are cornified (“superficial” cells), serum progesterone testing should be done every 48 hours to detect the day of initial progesterone rise (usually between 2 to 3 ng/ml), which correlates with the LH surge triggering ovulation. That is called “day zero.” The female is most fertile, and can be bred with good conception rates, between two and seven days after “day zero.” The number of breedings and the optimal day(s) of breeding depends on the type of semen (fresh [e.g., live-cover or trans-cervical insemination], chilled/extended, or frozen).
If LH testing is used to determine the most precise ovulation timing, daily serum samples must be taken once the vaginal cytology contains more than 70 percent “superficial” cells. Initial rise in progesterone or occurrence of the LH surge is confirmed around 48 hours later by running an additional progesterone test. At the time of breeding, progesterone should be above 5 ng/ml.
To economize ovulation timing, daily serum samples can be saved (refrigerated or frozen) and selected for later LH testing based on estimated initial rise in progesterone.
Q: How does a breeder manage a “maiden” bitch?
A: Primiparous (maiden) bitches should have a veterinary exam prior to breeding to ascertain general health, and specifically to rule out problems (vaginal strictures and inverted nipples) that could arise during breeding, whelping, or nursing.
A discussion with your vet about the canine estrous cycle, ovulation-timing techniques, and breeding management, as well as guidance in performing screening tests for genetic diseases common to your breed, should take place prior to mating.
A screening test for Brucella canis is advised annually for stud dogs and before each breeding for brood bitches. Brucella testing should occur even in the maiden bitch, as the infection can be transmitted without breeding.
Vaginal cultures are not necessary for healthy bitches; normal vaginal flora is not harmful to stud dogs nor detrimental to conception.
Also, the vet staff and client need to come to an agreement beforehand concerning the management of dystocia, or difficulty in whelping, should it occur.
Q: There are different methods of accomplishing a breeding. What are they?
A: Conception is most likely with a “live cover,” or natural breeding, with “ties.” But artificial insemination (AI) breeding, using a fertile stud dog and proper timing techniques, can be highly successful. AI is needed when using fresh-chilled or frozen semen, as well as with geriatric or inexperienced stud dogs or aggressive bitches.
AIs are best accomplished using a clean, rigid, mare uterine infusion pipette, allowing placement of semen near the cervical opening in the upper vagina. The successful use of frozen semen requires intrauterine deposition, now possible with rigid endoscopy through the cervix, transcervical insemination (TCI) being an additional tool for experienced vets, reducing the possible need for surgical implantation. Another option when using frozen semen is surgical implantation.
Q: After the bitch is bred, if she is not in whelp, what would a breeder expect to see?
A: Following estrus and breeding, the bitch enters diestrus. During diestrus, the normal bitch becomes refractory to breeding, less attractive to males. Vaginal discharges become mucoid and diminished, and vulvar edema slowly resolves. Vaginal cytology is altered by reappearance of noncornified (“parabasal”) epithelial cells and, frequently, white blood cells. Diestrus usually lasts about two months in the absence of pregnancy. Bitches normally experience a false pregnancy if not actually pregnant at the end of diestrus.
Q: What happens after diestrus?
A: After diestrus the bitch enters anestrus. The interestrus interval (the period between outwardly apparent hear cycles) consists of diestrus and anestus and normally varies from four and a half to 10 months in duration, with seven months the average.
Q: What is the anestrus phase?
A: The anestrus phase is characterized physically by apparent reproductive inactivity, although hypothalamic, pituitary, and ovarian hormonal fluctuations are occurring. During anestrus, the uterus is undergoing recovery and repair following a false or true pregnancy. The normal bitch is neither attractive nor receptive to male dogs. Little vaginal discharge is present, and the vulva is relatively small.
Vaginal cytology taken during anestrus finds small “parabasal” cells, with occasional white blood cells and small numbers of mixed bacteria representing normal flora. Anestrus normally lasts from one to six months, before the bitch enters proestrus again and starts another heat cycle. At least two months of anestrus are required for fertility.