Pyometra is a condition in which the uterus fills with pus. This can be a life-threatening illness that requires emergency surgery. It can occur in any age intact female dog, however older dogs are more prone to this disorder.
Pyometra occurs because of hormonal changes in the female’s reproductive tract following a heat cycle. During a heat cycle, a female dog’s progesterone spikes and remains high for several weeks to months to prepare the body for pregnancy. The uterine lining gets thick during this hormone elevation. Once a dog has several consecutive heat cycles without pregnancy, the uterine wall thickens and, in time, cysts can form. This is known as cystic endometrial hyperplasia. These cysts secrete fluid and make for an excellent environment for bacteria to proliferate. The fluid then accumulates within the uterus. The cervix allows bacteria to enter the uterus since it is relaxed during estrus. These factors are what lead to a severe infection or pyometra.
In some instances the cervix remains open, allowing for drainage of the accumulated pus. In other circumstances, the cervix remains closed. Signs of pyometra include inappetence, lethargy, depression, vomiting, diarrhea, abdominal distention, and/or fever. The bacteria within the uterus can release toxins and affect the kidneys. If this occurs, your pet may drink more and have increased urine production.
Basic bloodwork can be used if pyometra is suspected. A dog with an infected uterus will have a high white blood cell count, particularly neutrophils since they help to fight off bacterial infections. X-rays may be used to look for an enlarged uterus, but the most sensitive test to diagnose pyometra is ultrasound. The thick walled, fluid filled uterus can be seen near the bladder.
Treatment for pyometra requires surgical removal of the infected uterus and ovaries. Younger patients, and those diagnosed early in the disease process are the best surgical candidates. Sick patients have increased anesthetic risks. Patients that are very ill may need intravenous fluids and antibiotics prior to the surgery. Any delay in surgery increases the risk of uterine rupture, which can lead to a potentially fatal peritonitis (inflammation of the peritoneum, which covers the inside of the abdomen and organs). Following surgery, antibiotics are given for two weeks to help with any possible infection. Medical treatment of pyometra is not typically recommended and is only reserved for those patients in which breeding capabilities are trying to be kept intact.
Without treatment, the chance of resolution is very slim and the risk of severe illness is very likely. Rupture of the uterus and impending peritonitis is potentially fatal, therefore prompt treatment is recommended. If you are concerned that your pet has a uterine infection, see your veterinarian as soon as possible.