Pyometra is the medical term used to describe an infected uterus. This infection can be open (draining pus from the vagina) or closed (pus is contained in the uterus by a closed cervix). In the past, pyometra was considered to be simply a uterine infection. Today it is now known as a hormonal abnormality and a secondary bacterial infection may or may not be present. This disease mainly affects the middle aged female dog that has not been spayed. Pyometra follows a heat cycle in which fertilization did not occur. Many times within two to four months after the cycle, the female starts showing signs of the disease. In the simplest terms, it is an infection in the uterus.
The two main hormones produced by the ovaries are estrogen and progesterone. An excessive quantity of progesterone, or the uterus becoming oversensitive to it, causes pyometra. In either case, cysts form in the lining of the uterus. These cysts contain numerous secretory cells, and large quantities of fluids are produced and released into the interior of the uterus. This fluid, along with a thickening of the walls of the uterus, brings about a dramatic increase in the overall size of this organ.
How do bacteria get into the uterus? The cervix is the gateway to the uterus. It remains tightly closed except during estrus. When it is open, bacteria that are normally found in the vagina can enter the uterus rather easily. If the uterus is normal, the environment is adverse to bacterial survival. When the uterine wall is thickened and cystic, perfect conditions exist for bacterial growth. When these abnormal conditions exist, the muscles of the uterus cannot contract properly. This means that bacteria that enter the uterus cannot be expelled.
What are some of the signs of a dog that has pyometra? The clinical signs depend on whether or not the cervix is open. If it is open, pus will drain from the uterus through the vagina to the outside. It is often noted on the skin or hair under the tail or on bedding and furniture where the dog has laid. Fever, lethargy, anorexia, and depression may or may not be present.
As the body attempts to flush out the build-up of waste products through the kidneys, the animal will drink excessive quantities of water (polydipsia) and urinate large amounts frequently (polyuria). She will lick at her vaginal area while the cervix is still open and the uterus is discharging a white fluid. She may run a low-grade fever and if blood work is done, she will show an elevated white blood cell count. As the uterus increases in size and weight, the dog shows weakness in the rear legs, often to the point where she cannot rise without help. As the dog enters kidney failure, she stops eating and becomes very lethargic.
If the cervix is closed, pus that forms is not able to drain to the outside. It collects in the uterus causing distention of the abdomen. The bacteria release toxins which are absorbed into circulation. These dogs often become severely ill very rapidly. They are anorectic, very listless, and very depressed. Vomiting or diarrhea may be present.
Toxins from the bacteria affect the kidneys ability to retain fluid. Increased urine production occurs, and the dog drinks an excess of water. This occurs in both open- and closed-cervix pyometra.
Dogs that are seen early in the disease may have a slight vaginal discharge and show no other signs of illness. Most dogs with pyometra are not seen until later in the illness. A very ill female dog that is drinking an increased amount of water and has not been spayed is always suspected of having pyometra. This is especially true if there is a vaginal discharge or an enlarged abdomen.
Since toxicity may develop very quickly in dogs with pyometra, it needs to be treated promptly. Dogs will receive intravenous fluids, usually for several days, and antibiotics. In most cases, the preferred treatment is a complete ovariohysterectomy (spay). This removes the ovaries, oviducts, uterus, and all associated blood vessels. These animals can be a surgical challenge because of their poor overall condition. In some females valued for breeding, prostaglandin and antibiotic therapy may be tried instead of surgery. The prostaglandin is given for 5-7 days and causes the uterus to contract and expel the fluid. In mild cases, when the cervix is still open and the fluid is draining, the success rate is excellent. This therapy should only be used in dogs 6 years of age or younger, who are in stable condition, and have an open cervix. Prostaglandins can have side effects, especially after the first dose, including restlessness, panting, vomiting, increased heart rate, fever, and defecation.
The infection is not only life threatening on its own, but it can also cause kidney failure through bacterial toxins. If treated quickly with surgery and antibiotics, approximately 90 percent of dogs affected with pyometra will survive.
If an owner decides not to have surgery on their pet, the other option is medical management. This method of treatment involves the injection of hormones, called prostaglandins, to change the environment in the uterus. Antibiotics are also given. Medical treatment of pyometra is not recommended.
It takes two days for the hormone injections to take effect, during which the pet could die of infection or kidney failure. There is also a high incidence of recurrence of pyometra with medical management. Furthermore, not all pets respond to this therapy and require life-saving surgery after this therapy has failed.
So obviously the best treatment for this disease is to have your dog spayed.
My rating: Spaying bitches not used for breeding: (4)