By Jennifer Coates, DVM
How do you know if your cat has pyometra? Sometimes the symptoms are straightforward, but at other times the disease can be tricky to diagnose. Knowing the signs of pyometra can, quite literally, save your cat’s life.
What is Pyometra?
Pyometra is defined as an accumulation of pus within the uterus, which can develop because of the hormonal, anatomical, and physiological changes that occur after a cat has gone through a heat cycle but does not become pregnant. Bacteria then take advantage of the situation, resulting in a potentially fatal infection.
What are the Symptoms of Pyometra in Cats?
Some cats with pyometra show no signs, or may show vague clinical signs like lethargy, fever, dehydration, and poor appetite, even if they are suffering from very advanced disease.
Vomiting may also be present. Because the signs of pyometra can be mild and/or ambiguous, abdominal imaging (x-rays and/or ultrasound) is sometimes the only way to definitively diagnose or rule out cases of pyometra in cats.
If a cat with pyometra has an open cervix, pus (often tinged with blood) will drain from the cat’s vagina, but fastidious feline groomers often clean it away before owners can observe it. Because the pus has a way to get out of the body, these cats may not show many signs of systemic illness.
In comparison, when a cat with pyometra has a closed cervix, the pus will accumulate within and distend the uterus, leading to pain, abdominal enlargement, and more obvious signs of illness. The uterus may eventually rupture, leading to peritonitis—infection of the abdominal cavity—which is fatal without aggressive treatment.
While increased thirst and urination are classic symptoms of pyometra in dogs, these clinical signs are rarely observed in cats.
What Puts a Cat at Risk for Pyometra?
The probability of a cat developing pyometra increases with age, and affected cats have often gone through a heat cycle roughly a month before falling ill.
Intact females are at highest risk for developing pyometra, but the condition can be diagnosed in spayed female cats, as well. Here’s how:
When a cat is spayed in a traditional manner most of the uterus is removed, but a small portion attached to the cervix is left within the abdomen. This is called the uterine “stump.” An alternate form of spaying is becoming more popular in which the entire uterus remains in the body and only the ovaries are removed. Pyometras are extremely unlikely with either of these two surgical procedures, as long as the cat is no longer under the influence of reproductive hormones. Unfortunately, this can occur under certain circumstances.
Sometimes, ovarian tissue has been left behind within the cat’s abdomen. The tissue may be microscopic and therefore invisible to the surgeon’s eye, or a mistake may have been made and a larger piece of ovary remains.
Some spayed female cats also develop pyometras after coming into contact with their owner’s estrogen-containing topical products or after being treated with progestins for skin problems, a practice which is no longer in wide-spread use.
Treating and Preventing Pyometra in Cats
The best way to treat a cat with pyometra is to spay her as soon as her condition has been stabilized. The ovaries, entire uterus, and cervix are removed as one unit to minimize the chance of pus leaking into the abdomen.
When a spayed cat develops pyometra, the uterine stump is removed (or the whole uterus if only the ovaries were previously taken out) and any remaining ovarian tissue must be identified and excised. If an owner plans to breed the cat in the future, medical treatment is available that may eliminate the need for surgery that inevitably leads to infertility.
Spaying a female cat when she is young and healthy is the best way to prevent pyometra. The spay procedure is much more risky once the disease has damaged her uterine tissues and weakened her ability to withstand surgery and anesthesia.