A few infectious agents are transmissible between a dog and bitch at mating. Most of them, apart from Brucella canis, are of no consequence to the health and fecundity of your dogs. If the mating is by Artificial Insemination, the male is protected but can still potentially pass disease on to the bitch via his semen. As it is important to the success of your venture that you protect your valuable breeding dogs from such diseases, it is wise to insist on a health check of all dogs prior to mating.
Any male dog you are using for the first time should have be subjected to a preliminary semen examination for viability. In this way you can avoid an otherwise missed pregnancy if it happens to have low semen quality, giving you the opportunity to use an alternate sire.
Vaginal cultures are of little value in a pre-breeding examination as the vagina of the dog is never sterile anyway. It normally hosts a varied population of bacteria and other micro-organisms (including E. coli, Streptococcus, Staphylococcus, Pastuerella and Mycoplasma), that will be in healthy balance unless the dog has been treated recently with antibiotics or the bitch is otherwise unhealthy.
Brucellosis, on the other hand, is a serious infectious disease in dogs. Infected bitches will abort litters late in pregnancy. Infected males will suffer inflammation of the testes and subsequent infertility. Carrier dogs will shed the bacteria in all body discharges including urine, saliva, tears, feces, blood and birthing fluids. As a result, dogs can be infected at any time that they are in contact with other dogs, or frequenting places where other dogs have been. Luckily the disease is not common (and Australia is free of the disease). However, the admission of just one infected dog into your breeding establishment can infect all others and destroy your enterprise. The recommendation in countries where the disease is prevalent is to test bitches prior to every breeding, and dogs every six months.
There are several possible causes of low fertility in the dog. Here is a guide to sorting them out, and the order in which you should proceed.
Timing of the mating
When a mating fails to result in a pregnancy the most common reason is poor timing with respect to ovulation.
Natural rest for the bitch
Even where the bitch and the dog are fertile and timing of the mating is perfect, 15% of bitches will fail to get pregnant during a particular heat period. This is normal. Only when a bitch has failed to achieve pregnancy in two consecutive cycles is further investigation warranted
Fertility of the dog
As dogs age, they become more likely to suffer from reproductive infections and inflammation that may compromise the quality of their semen. Even a formerly virile and fecundate dog could suffer diminished fertility between one mating and the next. It is thus appropriate to have his semen examined for its quantity and viability, particularly if he has had a recent history of failing to get more than a few normally fertile bitches pregnant.
Age of the bitch
As already discussed, the fertility of the bitch drops rapidly once she gets to “middle age” – by six years old her chance of conceiving drops by a third; once she is 7 years old, it drops by a half.
Once the male has been ruled out as a cause of infertility, the many possible causes in the bitch can be explored. Causes of infertility on the bitch’s side of the equation include problems with:
|Fertility Disorders in the Bitch||Possible Causes|
|– Sexual immaturity
– Hormonal dysfunction (obesity, or problems with thyroid or adrenal glands)
– Previous hormone treatments (growth stimulants, corticosteroids, progesterones)
– Excessive sports training
– Infection (e.g. canine herpes virus)
– Poor diet (e.g. too low in energy or fat)
|Fertilization of the eggs
|– Sperm disabled by infection (vaginal, uterine; in male – urinary, prostate)
– Egg passage blocked by inflammation of the oviduct
|Implantation of the embryos
|– Uterine infection
– Cystic endometrial hyperplasia
– Heat periods too close together (un-rested uterine wall)
|Disorders interrupting pregnancy
|– Embryos unviable due to genetic incompatibility of parents (same lethal recessive trait)
– Infection (viruses: herpes, canine distemper; parasites: toxoplasma; bacteria: salmonella, pasteurella, canine brucellosis)
– Toxins: large number of chemicals (e.g. in common cleaners and insecticides) and medicines may damage embryos, especially in the first 3 weeks of pregnancy.
Obviously, treatment for these fertility problems will depend on their origin. A thorough veterinary investigation will be required to ascertain the exact cause of infertility. This will include a review of the bitch’s history (previous cycles), any treatments that may have been given (particularly hormone treatments), the mating date, how the mating proceeded, any discharges from the vulva, and measurement of hormone levels in the bitch. Use of hormones to treat infertility can cause more problems down the track and must only be entertained when the reason for infertility has been identified with certainty and all other possible treatments have already failed.