Pyometra is a serious infectious disease in female dogs. It is also known as uterine inflammation. Pyometra usually occurs as dogs age or after their breeding cycle.
Pyometra occurs as a result of inflammation in the uterus. The uterus normally works in a cycle, and with each cycle, the uterine lining thickens and prepares with the estrus period. If the dog does not become pregnant or loses puppies after conception, the inner lining of the uterus peels off and sheds at the end of the cycle under the influence of the hormone estrogen. Sometimes, however, the cervix closes and the shed lining is prevented from draining. In this case, microorganisms can multiply in the uterus and lead to infection.
Pyometra can appear in dogs in several different ways. Open pyometra is when the cervix is open and a purulent (pussy) discharge is seen. Closed pyometra is when the cervix is closed and pus accumulates in the uterus. Pyometra is an emergency and requires treatment. Surgical removal of the uterus and ovaries (ovariohesterectomy) is usually recommended. This allows the infection to be controlled and the dog to recover. Early diagnosis and treatment are important for maintaining the dog’s health.
What Is Pyometra (Uterine Inflammation) in Dogs?
Pyometra in dogs is a serious and life-threatening infection of the uterus. The condition must be treated quickly and aggressively. Pyometra is a secondary infection caused by hormonal changes in a female’s reproductive system. After estrus (estrus), progesterone levels stay high for several weeks, causing the uterus to thicken in preparation for pregnancy. If pregnancy does not occur for several estrous cycles, the uterine thickness increases until cysts form in the uterus. This condition is called cystic endometrial hyperplasia. The thickened cystic uterus secretes fluids, creating an ideal environment for bacteria to thrive. In addition, high progesterone levels inhibit the ability of the muscles in the uterine wall to contract and expel any accumulated fluids or bacteria.
Another contributing factor is the prevention of white blood cells, which normally protect against infection, from entering the uterus during estrus. This normal formation allows sperm to safely enter the female’s reproductive tract without being damaged or destroyed by these white blood cells. The combination of these factors can often lead to life-threatening infections.
Pyometra (Uterine Inflammation) Symptoms in Dogs
Clinical signs depend on whether the cervix remains open. If the purulent discharge is clear, it will flow out of the uterus through the vagina. This discharge can appear on the skin or under the tail, or on your dog’s bedding and furniture. With an open pyometra, fever, lethargy, loss of appetite, and depression may occur.
If the cervix is closed, the resulting discharge cannot flow out. It collects in the uterus, causing the abdomen to swell. Bacteria release toxins that are absorbed into the circulation. Dogs with indoor pyometra get seriously ill very quickly. They are anorectic (will not eat), sluggish and depressed. Vomiting or diarrhea may also be present.
Toxins released by bacteria affect the kidney’s ability to retain fluid. Increased urine production occurs and the dog drinks large amounts of water to compensate. This occurs in both the open and closed cervix pyometra.
Causes of Pyometra (Uterine Inflammation) in Dogs
Pyometra in dogs is a result of inflammation inside the uterus. This inflammation is often associated with hormonal changes. Here are some factors that cause the development of pyometra:
Hormonal Changes: Pyometra is associated with hormonal imbalances, particularly in older or unsterilized female dogs. At the end of the estrus cycle, the inner lining of the uterus thickens and prepares under the influence of the hormone estrogen. But if she doesn’t get pregnant or her pregnancy ends, the inner lining of the uterus peels off and sheds. During this spill, as long as the cervix is open, there is a risk of microorganisms entering the uterus and infection.
Bacterial Infection: Pyometra is usually caused by a bacterial infection. Although the uterus is normally in a sterile environment, it is possible for bacteria to settle in the uterus and develop an infection due to hormonal changes, a closed cervix or an inadequate immune system.
Estrogen Effect: While the hormone estrogen encourages the thickening of the inner lining of the uterus, it also ensures the closure of the cervix. If the lining of the uterus does not shed completely and the cervix remains closed, the estrogen accumulating in the uterus can lead to inflammation of the lining and infection.
Age: Pyometra is more common in older dogs. The aging process can cause hormonal changes and weakening of the immune system, increasing the risk of pyometra.
Not being sterilized: Unneutered female dogs may be at risk for pyometra. Sterilization (ovariohesterectomy), along with removal of the uterus and ovaries, reduces the development of pyometra by preventing hormonal changes.
An important point is that pyometra is a complex condition resulting from a combination of many factors. Any female dog is at risk of developing pyometra, but older dogs that have not been neutered are at higher risk. If you notice signs of pyometra in your dog, it is important to consult a veterinarian immediately.
Diagnosing Pyometra (Uterine Inflammation) in Dogs
The diagnosis of pyometra in dogs is made by the veterinarian through physical examination, evaluation of symptoms, and some laboratory tests. Here are the common methods used to diagnose pyometra:
Physical examination: The veterinarian will assess the dog’s general health and examine the symptoms. During this examination, the dog’s abdomen can be palpated and signs such as uterine enlargement or tenderness can be looked for. Dogs examined in the early stages of the disease may have a slight vaginal discharge and no other signs of disease. However, most dogs with pyometra appear later in the disease. Any very sick female dog that is drinking increased amounts of water and has not been neutered should be suspected of having pyometra. Diagnosis is approached, especially if there is a vaginal discharge or a painful, enlarged abdomen.
Blood and Urine Tests: Blood tests are used to assess the dog’s general health and signs of infection. Tests such as a blood count (complete blood count), biochemistry panel, and markers of inflammation can provide values that indicate the presence of infection and the dog’s immune system response. Dogs with pyometra usually have a drastic increase in their white blood cell count. An increase in globulins, an immune system-related protein, is often seen in the blood. Due to the toxic effects of bacteria on the kidneys, the specific gravity (concentration) of the urine is very low. However, these changes are nonspecific and can be present in any dog with a major bacterial infection.
Radiography or Ultrasonography: Radiography (x-ray) or ultrasonography (imaging using sound waves) methods may be used to evaluate for uterine enlargement, fluid buildup, or signs of infection. These imaging modalities can help confirm the diagnosis of pyometra. If the cervix is closed, abdominal radiographs (X-rays) will usually identify the enlarged uterus. If the cervix is open, there will usually be so little uterine enlargement that the radiograph will be inconclusive. An ultrasound examination can help identify an enlarged uterus and differentiate it from a normal pregnancy.
Vaginal Discharge Rating: Evaluation of vaginal discharge is an important step in diagnosing pyometra. A purulent or purulent discharge may be a sign of pyometra. The veterinarian may take a sample of the vaginal discharge and send it to the laboratory for examination under a microscope.
Pyometra (Uterine Inflammation) Treatment in Dogs
The preferred treatment is surgical removal of the uterus and ovaries by performing an ovarian hysterectomy (sterilization). Dogs diagnosed at an early stage of the disease are excellent candidates for surgery. Pyometra surgery is a little more complicated than routine sterilization at this stage. However, most dogs are diagnosed when they are quite sick, resulting in a more complicated surgical procedure and a longer hospital stay. Intravenous fluids are required to stabilize the dog before and after surgery. Antibiotics are usually given two weeks after surgery.
For most dogs, surgery is highly recommended to treat pyometra. There is a medical approach to treating pyometra, but the success rate is highly variable and there is considerable risk and possible long-term complications. Prostaglandins are a group of hormones that reduce the level of progesterone in the blood, relax and open the cervix, causing the uterus to contract and expel bacteria and pus. They can be used to treat this disease, but they are not always successful and have some important limitations.
- They cause side effects such as restlessness, panting, vomiting, defecation, salivation and abdominal pain. Side effects occur about fifteen minutes after administration and usually last for several hours. They become progressively milder with each successive treatment. Pain can be reduced by exercising or distracting your dog for about 30 minutes after the injection.
- There is no clinical improvement for approximately 48 hours, so severely ill dogs needing immediate life-saving treatment are bad candidates.
- Because prostaglandins cause the uterus to contract, it is possible for the uterus to rupture and the infection to spread into the abdominal cavity, resulting in a severely life-threatening condition known as peritonitis. This most likely happens when the cervix is closed.
The use of prostaglandins to treat pyometra has variable success rates and risks such as recurrence of the disease. Your veterinarian will help you decide on the best course of treatment for your dog’s needs.
Prevention of Pyometra in Dogs
You can take the following precautions to reduce the risk of pyometra in dogs:
Sterilization: Neutering is the process of removing the uterus and ovaries in female dogs. Sterilization greatly reduces the risk of pyometra. Removing the uterus and ovaries inhibits hormonal changes and prevents shedding of the uterine lining. Sterilization also reduces the risk of breast cancer and other reproductive system diseases.
Regular Veterinary Checks: It is important to take your dog to the veterinarian regularly. The veterinarian will assess the dog’s general health, check for signs of infection and guide you to take the necessary precautions.
Observing Risky Groups: Older female dogs, non-sterilized dogs, and dogs that have had pyometra in the past are at higher risk for pyometra. It is important to pay special attention to these groups and to have regular veterinary check-ups.
Early diagnosis and treatment are important because pyometra is a serious health problem. If you notice signs of pyometra in your dog, it is important to contact a veterinarian immediately.