By Albert H. Markway, DVM
This article originally appeared in the December 1994 issue of COONHOUND BLOODLINES.
Keep the stress at breeding time down to a minimum. Increased stress decreases fertility. There are many types of stress: heat stress, cold stress, etc. The long trip to the stud dog can be stressful or relatively stress-free, depending on what you make it. Make it non-stressful. Make occasional stops to let her exercise and empty her bladder, bowels, and eat and drink. Make a cool (or warm, depending upon the season) and comfortable dog box.
If we are going to try to understand the breeding problems we encounter in dogs, it is essential that we first understand the normal reproductive cycle and the variations that occur within its normal limits. Most bitches go through puberty and their first heat cycle at seven-twelve months, but as early as five months or as late as eighteen months is within the normal range. Some breeds and some individual females have only one heat cycle per year.
Most bitches will show some swelling of the vulva and some bloody discharge for about zero to ten days before she is ready to accept the male. This phase of her heat cycle is called proestrus. The bloody discharge gradually subsides and usually becomes a clear amber color when the bitch is ready to accept the male. The bitch will usually accept the male and allow breeding for three to ten days. The stage of the cycle during which the female will allow mating is called estrus. Some bitches are as regular as clockwork, and you can predict exactly when they will be in heat and how long each stage will last. Others are completely unpredictable from one cycle to another.
If you have experienced infertility problems, but your bitch has a normal cycle, then bacterial infection of the uterus should be considered as a potential problem. The uterus is very difficult to culture. Bacteria are normal inhabitants of the vaginal tract, and since this is generally what we culture, a positive bacterial culture does not mean that this is what is causing the infertility. But if we culture and run an antibiotic sensitivity test, this can give us an idea of what antibiotics will work on the bacteria present, if it is indeed the cause of the infertility. Some bacteria are very resistant, and there may be only one or two antibiotics that are effective against them. Some antibiotics can be given by vaginal infusion, but systemic therapy with effective antibiotics should be given for two to four weeks. One or two doses of penicillin isn't going to do the job.
Infection with the bacteria Brucella canis (canine brucellosis) most often causes abortion, but can also be responsible for infertility. Antibiotics are not effective against this disease. A simple blood test can be run to test for canine brucellosis. Since this is such a serious reproductive disease in dogs, all females should be tested before being bred.
Another potential problem in bitches with normal cycles is obstruction of the reproductive tract. Strictures, adhesions or abnormal membranes in the vaginal tract can usually be detected with a vaginal exam. But if there is an obstruction in the uterus or oviducts, diagnosis and treatment is much more difficult and expensive.
If we have looked back over our carefully kept records and have determined that there is some phase of our bitch's estrous cycle that is not normal, then the nature of the abnormality may help us solve the problem.
If, for instance, the length between cycles is less than 4 to 4˝ months from one estrus to the next, this is too short of a time period for the uterus to return to its normal state. Your veterinarian may want to use Mibolerone to keep her from coming into heat until after this critical time has passed.
Some bitches, especially bitches coming into heat the first time, may experience a “split” or “false” heat. They may show some swelling and bloody discharge for a few days and then return to normal. A normal heat cycle will usually occur four to six weeks later. This second or “true” heat cycle should be fertile.
If the interval between heat cycles is longer than normal, hypothyroidism (low thyroid hormone production) is a prime candidate to consider as the cause of the problem. A blood test can help to determine if your dog produces adequate thyroid levels, and if it does not, thyroid hormones may be supplemented. Since there is a hereditary predisposition to hypothyroidism, you may want to consider this before you decide whether you still, in fact, want to breed this bitch.
Occasionally a bitch will have an apparently normal cycle, but will never reach the point where she will accept the male. If it has been determined that she had no vaginal strictures or obstructions which may cause pain when the male penetrates, then it is very likely primarily a behavioral problem. We must try to determine when ovulation is occurring to plan our mating. Vaginal cytology smears, progesterone assays and LH assays are all means of determining when ovulation occurs. Vaginal cytology is the least expensive, but also the least accurate. Progesterone assays are moderately expensive and highly accurate. LH assays appear to be very accurate but are the most expensive methods to determine when ovulation occurs. Your veterinarian may be able to use one or more of these methods to help pinpoint ovulation and plan a breeding. The bitch may need to be muzzled and restrained and/or given a mild tranquilizer or possibly even bred by artificial insemination.
Failure to ovulate, or delayed ovulation, is another potential problem causing infertility. Some bitches with this problem will show a prolonged period of acceptance for the male. This should definitely be suspected if standing heat lasts more than ten days. A progesterone assay about thirty days after the onset of standing heat will help determine whether ovulation did occur. If it did not, plans can be made to induce ovulation in the next heat period. Your veterinarian can administer HCG, LH or GnRH early in the next standing heat period to induce ovulation.
Another problem is the young bitch that fails to cycle at all. Most of the time you just need to have a little more patience. But if a bitch has reached 1˝ to 2 years old and still has not come into heat, the prospects are bleak. Again, hypothyroidism is a possible cause that can be treated. But this problem may also be associated with an ovary or adrenal gland dysfunction or chromosome abnormality. And even if you can diagnose the cause of the problem, treatment would most likely be unsuccessful.
Probably the most common cause of infertility is faulty timing of breeding. Most breedings are planned on a certain day of the cycle. Some breeders recommend the 10th day, some the 12th, some the 14th, etc. Well, if your bitch is average, that's fine. If you have an average bitch and you breed her as soon as she will take a male, or one or two days later, or anytime from the 10th to the 14th day of her cycle, chances are very good that you'll get puppies. Because the male sperm lives so long, any breeding early in standing heat should be successful. In the average bitch, if you are breeding natural, and have repeated access to a male, I would breed on the first day she'll accept the male, and then every other day for two or three breedings. If you can only breed once, I would breed on the day after the first day she'll accept a male.
If you don't have an "average" bitch, or you are planning an artificial insemination breeding, you had better plan on doing some type of ovulation timing testing to plan your breedings for best results.
In the “average” bitch, ovulation occurs on the first or second day of standing heat. A bitch’s egg must undergo two maturation divisions after being ovulated, prior to being fertilizable. This process takes about two days. The eggs are then viable for another two to three days after this. Fresh sperm lives five to seven days or more in the female reproductive tract in the dog. Fresh chilled semen lives two to three days, and frozen sperm lives only twelve to twenty-four hours after thawing. So, you can see why timing is so important with artificial insemination.
Inbreeding tends to reduce overall reproductive efficiency. Inbreeding and linebreeding (which is a form of inbreeding) are valuable tools in establishing and fixing desirable traits in our hounds. But I feel that this practice is probably also responsible for some of the subtle reproductive problems that we experience.
I hope that this article has helped you to at least gain some insight into the more common reproductive problems in the bitch. Because of the relatively long period between estrous cycles, it behooves us to make the most of each heat period. Good luck in your endeavors.