Pyometra is a condition affecting unspayed female dogs that occurs when the uterus becomes infected with bacteria and fills with pus. Pyometra in dogs typically occurs in the weeks after a heat and is a serious, life-threatening condition. This article will discuss the causes, symptoms, and treatments for pyometra in dogs.
What is pyometra in dogs?
Pyometra in dogs is a severe condition and acute or chronic inflammation of the uterine wall. It is mostly characterized by cystic endometrial hyperplasia, cystic dilation of endometrial glands, and accumulation of pus in the uterus. Risk of developing pyometra increases with age with the majority of affected dogs being greater than 7 years of age.
What causes pyometra in dogs?
The period after a female dog's heat cycle, when her body produces more progesterone, makes her more likely to get a uterine infection (pyometra). Pyometra typically affects female dogs 2-4 months after their last heat. This bacterial infection can happen because progesterone makes the uterine cells proliferate, makes the white blood cells less active, and makes the cervix close up.
These effects are made worse by estrogen during the time before the diestrus phase. Each time a female dog goes through an estrous cycle (including the proestrus/estrus period), her risk of getting a uterine infection goes up, since these hormonal changes accumulate.
The end result is a severe bacterial infection of the uterus, typically caused by E-coli bacteria. The bacteria release toxins that contribute to the development of the clinical signs of pyometra in dogs.
What is the difference between open and closed pyometra?
In an open pyometra, the cervix is still open and pus can drain from the uterus. In a closed pyometra, the cervix is closed and pus cannot drain from the uterus. Closed pyometra is a more serious condition because the infection can result in sepsis and spread to other organs.
The ability to release purulent exudate from the uterus (i.e. open-cervix versus closed-cervix pyometra) determines how likely a dog is to get sepsis. If the pus and exudate can't be removed (e.g. closed-cervix pyometra), there's a higher risk of bacteria toxins getting into the dog's bloodstream and causing endotoxemia. Open-cervix pyometra can also lead to endotoxemia, especially if it's not treated right away.
What are the symptoms of pyometra in dogs?
Common symptoms of pyometra in dogs include:
- Increased thirst
- Frequent urination
- Decreased appetite
- Vaginal discharge (this may not be present in a closed pyometra)
- Fever
- Lethargy
- Vomiting
A dog with pyometra may also have a fever and an enlarged, soft abdomen due to the enlarged uterus. In severe cases, there may be collapse, pale mucous membranes, rapid breathing and heart rate.
How is pyometra in dogs diagnosed?
Pyometra is typically diagnosed based on the dog's symptoms and a physical examination. Typical symptoms of pyometra combined with a recent heat 2-4 months prior are very suggestive. It is therefore important to discuss your dog's recent heat cycles with your veterinarian.
An x-ray or ultrasound may also be performed to confirm the diagnosis. An enlarged uterus is commonly observed on abdominal radiographs and it usually appears as a mass. Abdominal ultrasonography is the most essential diagnostic test for pyometra in female dogs. In one study, a correct diagnosis was made in 90% of cases.
Your veterinarian will also perform blood testing such as a complete blood count (CBC) and biochemical profile. These blood tests will often reveal an increase in white blood cells (leukocytosis) and sometimes a low red blood cell count (anemia). A biochemical profile may show elevations in globulin proteins, and liver and kidney enzymes.
How is pyometra in dogs treated?
The only way to definitively treat pyometra is through surgery. The infected uterus and ovaries must be removed and this is typically done through a spay procedure (ovariohysterectomy). Surgery is considered the best course of treatment because it permanently prevents pyometra from recurring and also prevents other uterine diseases, such as uterine cancer. Your veterinarian will start antibiotics prior to surgery and continue for 7-10 post-operatively.
Treating pyometra in dogs with antibiotics as a sole treatment is not effective and is not recommended. With that being said, in young animals that are otherwise healthy, medical treatment may be a valid choice. However, it is not recommended for patients that are not meant for breeding and for these dogs, surgery should be performed. Medical treatments include prostaglandins and progesterone receptor, antagonists.
What is the prognosis for female dogs with pyometra?
The prognosis for dogs with pyometra is generally good if treated early and most dogs make a full recovery. The mortality rate following surgery is 5-8% and increases dramatically if there is a uterine rupture. If pyometra is left untreated, it can be life-threatening due to uterine rupture and sepsis.
The success rate for dogs that were treated medically and not surgically is greater than 80%. The fertility rate is approximately 70%, however, the recurrence rate of pyometra is up to 30%.
What are the early clinical signs of pyometra in dogs?
The most common early clinical signs of pyometra in dogs are increased thirst, urination, and reduced appetite. Other early signs include fever, lethargy, and vomiting.
How can pyometra in dogs be prevented?
The best way to prevent pyometra in dogs is to spay your dog before her first heat cycle. This simple surgery will remove the ovaries and uterus, thus eliminating the possibility of pyometra ever developing. If you are not planning on breeding your dog, spaying her is always the best option.
Is pyometra curable in dogs?
Yes, pyometra is curable in dogs if it is caught early and treated promptly. Surgery is the only way to cure pyometra and the success rate is high if the dog is otherwise healthy. Medical treatment may be an option for young, healthy dogs but is not recommended for older dogs or dogs that are not meant for breeding.
How quickly does pyometra develop?
If it is a closed-cervix pyometra, clinical signs of pyometra can develop very quickly, sometimes within a matter of hours and a few days. If it is an open-cervix pyometra, the clinical signs of pyometra can take days to weeks to reveal.
In summary, pyometra in dogs is a serious uterine infection that can be life-threatening if left untreated. Common clinical signs of pyometra include lethargy, lack of appetite, increased thirst, urination and in cases of open-cervix pyometra, vaginal discharge. Surgery is the only definitive treatment and has a high success rate. Medical treatment may be an option for young, healthy animals but should not be used in patients that are not meant for breeding. Overall, with prompt treatment, the prognosis is very good with most dogs making a complete recovery. If you have any questions or concerns about pyometra affecting your dog, please speak with your veterinarian. Thank you for reading!