Pyometra: A Danger to Unspayed Pets

By: Jessica Colborn, DVM

TVMA Member
Magnolia, TX

Published February 2015

What is Pyometra?

Pyometra is an infection of the uterus that occurs in unspayed dogs and cats, usually a few weeks to a few months after a heat cycle. It can happen at any age, but the likelihood increases the older an intact female gets. In the U.S., we encourage spaying dogs and cats early to prevent unwanted pregnancies and mammary cancer. Pyometra is another important reason to spay your pet. Treatment for pyometra includes removing the uterus, also known as spaying. Spaying is a routine procedure when performed on a healthy cat or dog, but the risks for complications and death are greatly increased when it is performed as a treatment for a pet infected with pyometra. If you have decided to breed your pet, once you have finished breeding and don’t want another litter, you should promptly spay her! The more heat cycles a cat or dog has without getting pregnant, the higher the risk for a uterine infection.

Why is Spaying Your Pet Important?

Many clients are hesitant to spay their pet for a variety of reasons. They think if they keep their pet from getting pregnant then they don’t have to worry about the risks associated with an unspayed female. Or sometimes they plan on having a litter in the future. Unfortunately, having heat cycles without pregnancy is the greatest risk factor for pyometra. Suddenly, we have to spay a sick animal that has an increased chance of complications with anesthesia and surgery and a greatly increased cost due to longer, more involved procedures and the need to hospitalize a patient before and after surgery.

Signs of Pyometra in Cats

In cats, we typically see this disease in those that are used for breeding. Cats with pyometra usually have a discharge of pus from their vulva. She is usually not showing signs of severe illness but may show signs persisting for weeks to months that include lethargy, not grooming herself and decreased appetite. You may also notice her drinking and urinating more.

Your veterinarian may take X-rays or perform an ultrasound to confirm the diagnosis of pyometra. They may also do bloodwork to make sure the cat is healthy enough to undergo surgery to remove the pus-filled uterus. However, we can try to save the cat’s uterus by giving several weeks of antibiotics and prostaglandins to remove all the pus from the uterus. Unfortunately, the cat probably developed pyometra because of abnormal uterine tissue (cystic endometrial hyperplasia or possibly a tumor) and that means that her chances of having a normal pregnancy in the future will be decreased (Rand, Problem-based Feline Medicine). There is increased risk of surgery in a cat with pyometra, but the long-term prognosis after spaying is good.

Signs of Pyometra in Dogs

In dogs, pyometra causes them to get sick very quickly. She may have an open pyometra with obvious pus coming from her vulva or a closed pyometra where all the pus builds up inside the uterus, making diagnosis more difficult. Signs will include lethargy, decreased appetite, vomiting, fever, abdominal pain, increased drinking and urinating and shock.

Your veterinarian will use X-rays, ultrasound and bloodwork to aid in making the diagnosis. If the uterus is draining pus, medical therapy with antibiotics and prostaglandins may be considered for treatment. However, trying to save a uterus for future breeding purposes puts the life of the dog at great risk. Medical treatment increases the risk of uterine rupture and death so most veterinarians strongly recommend surgery. The dog may be so sick that she must be stabilized with IV fluids and antibiotics before surgery, but usually we want to remove the pus-filled uterus as soon as she is stable enough. After surgery, she must stay on antibiotics and be monitored for possible complications such as organ failure or clotting problems.

If you do not plan on breeding your pet or you are unsure, please spay her before she develops pyometra! If money is a concern, ask your veterinarian or call your local shelter to get information on spay and neuter assistance. These programs will spay a healthy girl at minimal cost, but they generally will not be able to treat a pet for pyometra.

Jessica Colborn, DVM, lives in Magnolia, Texas. Dr. Colborn practices as a relief and emergency veterinarian.