Pyometra in Canines and Felines

Pyometra is a disease of the uterus in both canines and felines. The veterinary condition develops when the lining of the animal’s uterus becomes infected. However, only non-spayed dogs or cats can acquire this life-threatening illness.

Heat Cycles and Pyometra

Unaltered dogs and cats go into heat several times each year, causing the uterus walls to thicken as the pet’s body prepares to support a pregnancy. Symptoms of pyometra start when more than a few heat cycles pass without the canine or feline becoming pregnant. The heat cycle prevents white blood cells from entering the animal’s uterus. Since white blood cells are necessary to prevent infection, the bacterium travels freely through the body and causes symptoms of pyometra. Other causes of this serious canine and feline illness include:

• The bacterium enters the female pet’s body through the vagina.
• Cysts form in the thickened lining of the uterus, increasing the likelihood of bacterial growth and infection.
• Some reproductive medications for non-spayed canines and felines contain hormones that contribute to the thickening of the uterine wall. Regular monitoring from a veterinarian is necessary for pets that take this medication to prevent pyometra from developing.
• The increased thickness of the uterine walls prevents the uterus muscles from contracting to push fluids and bacteria out of the pet’s body through the vagina.

Left untreated, pyometra causes extensive suffering and eventual death. The infection can cause immediate shock due to the presence of bacteria in the bloodstream. Anyone who suspects their female pet may have this life-threatening condition must seek emergency treatment from a veterinarian.

Symptoms of Pyometra in Dogs and Cats

The severity of pyometra disease depends on whether the canine or feline has an open or closed cervix. An open cervix is best in terms of this infection because it allows the animal to discharge blood, mucus, and pus built up in her body. Pet owners only notice symptoms of pyometra when the animal has an open cervix. In this case, there is a foul-smelling discharge. Here are the most common places to see the discharge:

• Anywhere on the skin

• The hair underneath the tail
• On blankets, pet beds, furniture, or anyplace else in the home where the pet has sat or laid down.

Pet owners should understand that their dog or cat can still have pyometra with an open cervix even if they don’t see or smell any discharge. If the discharge only appeared on the animal’s body, she may have removed it with self-grooming. Because of the open cervix and ability to discharge bacterial fluids, canines and felines with this type of pyometra don’t become as sick as those with symptoms while having a closed cervix.

A pet with a closed cervix is more likely to have severe symptoms or die from the infection. The blood, mucus, and pus that lead to bacterial infection remain within the dog or cat’s body because there is no way for her to discharge it with a closed cervix. This can quickly cause the animal to go into shock or experience sudden death. Symptoms for pet owners to look for include:

• Abdominal swelling that causes pain when touched
• Appetite loss
• Depression and lethargic behavior
• Excessive grooming near the vaginal area
• Excess thirst and urination
• Vomiting

Canines and felines with closed cervix pyometra appear much more ill and need urgent care no matter what the hour.

What to Expect at the Emergency Veterinarian

Veterinarians typically perform one or more of the tests listed below to determine if a dog or cat has pyometra.

• Blood test to check for high white blood cell count.
• Cultural analysis to study vaginal discharge contents with a microscope.
• Radiograph and/or ultrasound with a closed cervix to determine the thickness of the uterine wall and confirm or rule out pregnancy.
• Urinalysis to check the concentration of urine.

Due to the life-threatening nature of pyometra, canines and felines usually undergo an emergency ovariohysterectomy that removes the animal’s ovaries and uterus. The surgery can be risky because infected fluids in the uterus can spill to other parts of the body. After a hysterectomy, canines and felines need to remain under veterinary supervision at the clinic for at least a few days. They also require IV antibiotics while hospitalized and for the owner to administer antibiotics for several days after surgery at home.

Although not recommended by veterinarians, sometimes owners insist that their female dog or cat retain her fertility. In this case, hormone injections to expel the uterine contents are one treatment method, but the contractions it causes can lead to the uterus spilling its contents and ripping. This treatment method has a lower success rate, meaning the non-spayed canine or feline could develop pyometra again. Another drawback is that hormone injections take approximately 48 hours to take effect, which is time that severely ill pets don’t have to wait.

An intact female will continue to require hormone injections that can cause a range of side effects. These include:

• Abdominal pain
• Defecation
• Excessive panting
• Restlessness
• Salivation
• Vomiting

These symptoms lessen with each injection but still cause what many veterinarians consider unnecessary stress on the pet’s body. Most canines and felines recover from pyometra treatment that includes emergency surgery within several days. The condition is most common in older females that have gone through several heat cycles. That means any female pet who contracts pyometra will eventually die from it if the owner fails to seek prompt treatment.

Pet Owners Can Prevent Pyometra by Spaying Their Dog or Cat

Not only does spaying protect a female pet’s health, but it also prevents her from giving birth to several litters of puppies or kittens over her short lifespan. The American Animal Hospital Association recommends spaying kittens by 4 months, dogs up to 45 pounds at 6 months, and dogs over 45 pounds at 9 to 15 months. The reason for the slight delay with larger dogs is that they need to finish developing first.

While it’s best to spay before the first heat cycle, pet owners can bring their dog or cat to the veterinarian for this procedure at any age.

Medically Reviewed by Sara Ochoa, DVM