What is canine pyometra? Understand causes, symptoms, treatment

Canine pyometra, pronounced “pai-oh-meh-truh,” is a uterine infection. It can occur in several mammalian species.

A spayed dog rarely develops pyometra, which affects around one in four unspayed female dogs. 

Most American pet owners choose to spay their dogs, so you may never have to worry about pyometra.

Nonetheless, it’s always a good idea to be informed and be able to spot concerning symptoms early.

What causes pyometra?

In Latin, “pyo” means pus, and “metra” relates to the uterus — ergo, pyometra is a condition by which a female dog’s uterus develops a thick, bacterial fluid.

Pyometra is a secondary infection, meaning that it results from an initial medical concern. It’s related to changes in a female dog’s hormonal levels.

A female dog is in heat for an average of two weeks. Following this period, she will continue to have elevated progesterone levels (pregnancy hormones), and the uterine wall will thicken.

As a female’s body prepares for pregnancy, it restricts white blood cells (which help fight infection) from the uterus since white blood cells, while fighting off potential infection, can also attack healthy cells and limit sperm mobility.

However, should pregnancy not occur after several cycles, the uterine lining gets thicker and thicker, which eventually can lead to cysts forming.

The cysts are filled with fluid. Furthermore, heightened pregnancy hormones increase stress and limit the dog’s ability to contract her uterus, a movement that could help expel the fluid buildup.

This environment and the lack of white blood cells create a perfect scenario in which bacteria, usually E. coli, that enter through the dog’s relaxed cervix can flourish.

Are certain dogs at higher risk of contracting the disease?

As mentioned before, pyometra is a condition specific to female dogs. Because the infection results from a dog’s natural fertility cycle, it typically only affects dogs that have not been spayed.

Additionally, while not exclusive to older dogs, pyometra is more common in females at least six years old. Dogs typically go into heat twice each year. After several years without getting pregnant, the uterine lining has a higher chance of developing cysts that can lead to infection.

Besides age, other factors contribute to an increased risk of pyometra in dogs.

Some dog owners might use progesterone injections to treat certain medical conditions or to limit their dog’s fertility; significant hormonal fluctuation can increase the dog’s chance of developing pyometra.

Some studies also demonstrate that certain breeds are more susceptible to the infection, specifically golden retrievers, rottweilers, Bernese mountain dogs, Cavalier King Charles spaniels, rough-coated collies, and miniature schnauzers.

Is it easy for vets to diagnose pyometra?

Development of pyometra can present in different ways, but there are some key signs. As discussed above, elevated progesterone levels can inhibit a female dog’s ability to contract her uterus and expel excess fluid.

In some cases, you can see pus or bloody discharge draining from the dog’s cervix. In this scenario, the infection is called “open pyometra,” and your dog may otherwise appear relatively healthy.

However, while less common, some dogs suffer from “closed pyometra,” a condition in which the cervix is closed and unable to release the built-up fluid.

Closed pyometra is very dangerous and can have several symptoms. Your dog’s abdomen may swell, and the dog may experience fatigue, vomiting, and diarrhea. Urinary tract infections can be another warning.

In both forms of pyometra, you will likely witness your dog increase her water intake and urinate more frequently; this is the body’s attempt to flush out the toxins from the system.

Your vet will assess the dog’s age and disposition and then check the symptoms. Bloating and vaginal discharge are signs of pyometra.

The next step might include a blood test to determine your dog’s white blood cell count. A sharp increase in white blood cell count is indicative of infection.

Your vet may also test your dog’s urine, which can help reveal kidney stress from the bacterial infection.

Finally, you may consider an ultrasound to determine whether your dog has an enlarged uterus or fluid buildup.

How to treat canine pyometra

The best preventative treatment is to spay your female. However, not everyone chooses to do so.

Pyometra occurs in more than 20% of intact female dogs, but luckily, there is some treatment of pyometra options.

Remember, treatment is more successful if your veterinarian can diagnose pyometra early, so be sure to err on the side of caution should you notice any warning signs.

One option is surgery. Your vet will remove your dog’s reproductive organs (the ovaries and the uterus).

While this procedure is relatively safe for healthy dogs, such an invasive procedure can be riskier for dogs experiencing uterine enlargement or suffering from infection; their immune systems will already be weakened, so they may have a more difficult time recovering from surgery.

Your vet will employ antibiotics to assist with these risks.

The second option is medication. This method involves a hormone treatment that allows the dog’s cervix to relax and lets the body expel the built-up fluid.

Dog owners who don’t want to remove their dog’s reproductive organs (should they hope potentially breed the dog) often opt for this treatment.

However, the hormone therapy approach is much more effective for open pyometra. Furthermore, your dog will be at risk of the infection returning, and her chance of successfully breeding again may drop by 50%.

Can your dog die from pyometra?

Canine pyometra is a severe infection that can lead to death if left untreated; the bacterial infection will spread.

The uterus may also burst and leak toxins into the body. Should you notice discolored discharge or swelling in the weeks following your dog’s bleeding cycle, call your vet right away.

Treating pyometra can be costly (likely thousands of dollars), whereas spaying a healthy dog costs a few hundred dollars.

If you aren’t planning to breed your beloved pooch, it’s highly recommended that you get her spayed while still young. It’s just not worth the risk.

Most importantly, talk to your vet about recommendations based on your dog’s age and breed.