By Thomas K. Graves, DVM, PhD
Pyometra is a term that strikes fear in the heart of any dog breeder. Many a beautiful bitch has been unable to produce puppies because of this condition. It happens in the best of kennels and in the best of lines. The disorder, however, need not end the breeding career of a valuable bitch. Pyometra is a treatable disease, and afflicted bitches can often go on to produce litters.
Pyometra is a hormonal disease. The normal canine estrous cycle entails a surge in estrogen levels followed by a prolonged increase in the level of progesterone needed to support pregnancy. These hormonal events occur in non-pregnant as well as in pregnant bitches during the estrous cycle. In other words, whether a bitch is bred or not, she goes through the same hormone cycles, and there are effects of the uterus. In the non-pregnant uterus, exposure to high levels of estrogen followed by high levels of progesterone leads to a condition called cystic endometrial hyperplasia. This leads to swelling and fluid accumulation within the uterus. In some bitches, endometrial hyperplasia is accompanied by bacterial infection, resulting in the accumulation of pus within the uterus, the condition known as pyometra. The bacteria associated with pyometra are usually found in the normal, healthy vagina.
Pyometra occurs most commonly in middle-aged bitches, but can be seen in young bitches as well. Contrary to popular belief, it is not a disease of old bitches. It can happen at any age. Pyometra is usually described as being “open” or “closed” depending on the condition of the cervix. In an open pyometra, the cervix is relaxed and allows the uterine contents to drain from the vaginal tract, whereas in a closed pyometra there is no drainage due to the cervical barrier.
Clinical signs occur within 2 to 12 weeks when the bitch is in season, and are due to both local and systemic effects of pyometra. Local signs include a purulent or bloody vaginal discharge. This discharge sometimes has an unpleasant odor, and it can be quite copious in severe cases of open-cervix pyometra. There is sometimes a swelling of the abdomen associated with a fluid-filled uterus. Often affected bitches show no signs of systemic illness. In other cases, however, systemic signs can be severe. Some of these signs include fever, malaise, lethargy, inappetance. These signs can progress to sepsis, shock, and eventually death if the condition is left untreated. Closed-cervix pyometra is especially dangerous and life-threatening. One of the curious clinical signs of pyometra is polyuria/polydipsia (excessive urination and water intake), which is due to the effects of bacterial toxins on the urine concentrating ability of the kidneys.
It is important to differentiate between pyometra and a condition with which it is sometimes confused, pregnancy. Both occur at the same time after estrus. Both can be associated with mild vaginal discharge. Both can be associated with abdominal swelling. Both can cause changes in activity and behavior. In both cases, the uterus is palpably enlarged. Important diagnostic tests include a complete blood count, serum biochemical profile, and urinalysis. Vaginal cytology is an important diagnostic tool since it can reveal the presence of inflammatory cells and bacteria, indicative of pyometra. Abdominal radiography is often necessary to visualize an enlarged uterus and to rule out pregnancy. Abdominal ultrasound is even more useful, since it can detect pregnancy earlier than plain abdominal radiography.
Ovariohysterectomy is the preferred method of treatment of pyometra. However, in a valuable brood bitch, ovariohysterectomy may not be desirable. In most of these cases, medical treatment is possible. In recent years, the use of prostaglandin F2? has become another viable mode of treatment. PGF2? causes contraction of the uterus and expulsion of its contents. The drug is given by injection for 2 to 7 days while the uterus is emptied. There are side effects associated with the drug, including vomiting, abdominal pain, defecation, and salivation. The side effects can be severe, but usually subside within a short time after onset. Antibiotic therapy is also necessary to treat bacterial infection. PGF2? therapy has been very successful. Interestingly, previous pyometra and treatment with PGF2? does not impair future fertility. In fact, bitches experiencing an episode of pyometra are very likely to have a recurrence of pyometra following their next season if they are not bred. Bitches predisposed to pyometra should arguably, therefore, be either spayed or bred on each estrus cycle. In severe cases of pyometra with serious signs of systemic illness, more extensive therapy may be needed. Bitches in sepsis or shock require intravenous fluid therapy and intravenous antibiotic therapy. In some severe non-surgical cases, uterine lavage and flushing is required as an adjunct to PGF2? treatment.
There are no reports of hereditary pyometra in the veterinary literature. Anecdotally, however, some breeders claim the condition runs in certain lines. My personal opinion is that pyometra is a multifactorial condition, and that bitches prone to the problem (having a history of pyometra) should either be bred or spayed. Breedings should not be skipped on consecutive cycles in a bitch with a history of pyometra. If, in the opinion of the breeder and veterinarian, a bitch is not in condition to be bred on consecutive cycles, she should probably be spayed. In my own experience as a Pekingese breeder, I have seen very few bitches who are not in perfect condition to be bred on consecutive cycles, despite the conventional wisdom that states that bitches should be bred every other cycle. Scientific evidence to support this practice is lacking, and I am leaning towards the opinion that bitches should either be bred or spayed.
(This article originally appeared in COMMON MEDICAL DISORDERS OF THE PEKINGESE, ©Pekingese Club of America, Inc, and is reprinted with permission. Dr. Graves is an Assistant Professor of Internal Medicine at the University of Illinois College of Veterinary Medicine, and is a breeder/judge of Pekingese dogs, and is Chairman of Pekingese Club of America’s Health Committee.)
Thomas K. Graves, DVM, PhD
Diplomate, American College of Veterinary Internal Medicine