Pyometra is a serious, potentially life-threatening uterine infection that can make your intact female pet extremely ill. Our Peak Pet Urgent Care team wants you to understand this concerning condition so you can recognize if your pet is affected and take steps to reduce their disease risk.

What is pyometra in pets?

The term pyometra means “pus-filled uterus.” When a female pet experiences a heat cycle, progesterone causes the uterine lining to thicken in preparation for pregnancy. With repeated heat cycles, excessive or persistent tissue thickening occurs, a condition called cystic endometrial hyperplasia, which increases infection risk. In addition, while in heat, the pet’s cervix opens to allow in sperm, but this also can allow bacteria from the vagina to ascend into the uterus. Other contributing factors include the uterine muscle’s reduced ability to contract because of effects from progesterone and a decreased number of white blood cells (WBCs) in the uterus. WBCs help remove pathogens from the body, but during a pet’s heat cycle, WBCs are inhibited from entering the uterus so sperm can enter safely. 

Pyometra can be classified based on whether the pet’s cervix is open or closed:

  • Open — In an open pyometra, the cervix remains open, allowing pus to drain from the uterus via the vagina. This is the most common form of pyometra, and pet owners can observe a vaginal discharge from their pet.
  • Closed — In a closed pyometra, the cervix is closed, trapping pus in the uterus. This condition is much more serious because toxins can quickly enter the affected pet’s bloodstream.

In rare cases, a female pet can develop a stump pyometra, a condition that occurs if residual ovarian and uterine tissue remains after she has been spayed. 

What are pyometra signs in pets?

If your pet has an open pyometra, you may notice discharge on their hind end or bedding, but some pets, especially cats, groom away the evidence. In a closed pyometra, no vaginal discharge is present, but your pet’s abdomen may become distended as their uterus fills with pus. Other pyometra signs include:

  • Lethargy
  • Inappetence
  • Increased thirst and urination
  • Vomiting
  • Fever
  • Pale gums
  • Weakness or collapse

Pyometra should be suspected in any unspayed female pet who is ill.

What pets are at higher risk for pyometra?

Pyometra can occur in female pets of any age but is most common in middle-aged and older pets. Any breed can also be affected, but dog breeds at increased include rough-coated collies, rottweilers, miniature schnauzers, Cavalier King Charles spaniels, golden retrievers, Bernese mountain dogs, and English springer spaniels. Cat breeds at increased risk include Sphinx, Siamese, Abyssinian, ragdoll, Maine Coon, and Bengal.

How is pyometra in pets diagnosed?

Based on your pet’s history and clinical signs, our veterinary team may suspect pyometra. Tests that we may use to confirm the diagnosis and guide treatment include:

  • Blood work — We will perform a complete blood count (CBC) and biochemistry profile to assess your pet’s overall health and determine if the infection has affected their kidneys.
  • X-rays — Abdominal X-rays may reveal a distended uterus.
  • Ultrasound — An abdominal ultrasound is the best way to image and assess the uterus. This method can identify fluid inside the uterus as well as measure the uterine wall thickness.

How is pyometra treated in pets?

Pyometra is a medical emergency that requires prompt veterinary attention to prevent infection spread and death. Most pets need to be stabilized with fluid therapy and medications upon presentation. Additional treatment options include:

  • Surgery — Surgery to remove the pet’s ovaries and uterus is the treatment of choice for pyometra. While a typical spay is an uncomplicated procedure, this surgery is much more difficult when the uterus is infected. The tissue is engorged and extremely vascular, making excessive bleeding a concern, and care must be taken to avoid spilling the contents from the distended uterus into the pet’s abdominal cavity. As long as the surgery goes smoothly, 80% to 100% of pets recover. Aftercare usually involves administering pain medications and antibiotics, and your pet’s activity should be restricted for at least two weeks after surgery.
  • Prostaglandin therapy — For highly valuable breeding animals who have an open pyometra, prostaglandin therapy may be an option. This treatment causes the uterus to contract to help expel the pus from the body. Pets typically experience discomfort during the treatment, and about 77% of pets have pyometra recurrence. In addition, there is a risk of uterine rupture using this treatment. If the treatment is successful, the pet must be bred on the next cycle to help prevent recurrence. 

How is pyometra prevented in pets?

The good news is that pyometra is easily preventable. Having your pet spayed when they are young and healthy protects them from this dangerous disease and also decreases their risk for other health issues such as mammary cancer. Your primary veterinarian can help determine the best time to spay your four-legged friend. 

Contact our Peak Pet Urgent Care team if your unspayed pet has a vaginal discharge or exhibits illness signs.