Pyometra: Signs, Causes, and Care (Vet Answer)
A funny-sounding word with a very serious meaning
Your female dog is drinking more, panting, lethargic, and you know something just isn’t right. Never ignore that feeling. You know your dog better than anyone else, and if you think something is wrong, it probably is. And if your dog hasn’t been spayed, you could be seeing signs of pyometra: infection of the womb or uterus that can turn deadly if left untreated.
Any dog with a uterus can develop a uterine infection, and, although rare, even dogs that have had a laparoscopic or ‘keyhole’ spay, where only the ovaries are removed, can be at risk of pyometra. So, what is pyometra? Read on to find out.
What Is Pyometra?
An infected uterus or womb, sometimes referred to in practice as a “pyo”, is a relatively common condition affecting entire female dogs. It occurs most commonly in middle-aged to older dogs, but cases have been reported in dogs as young as 9 months.
In dogs, the uterus splits into two branches or ‘horns’ that allow multiple fetuses to be carried on each side. Female dogs come into season or estrus around every six months once they reach sexual maturity. This is when she becomes fertile and receptive to mating. If she becomes pregnant, all being well, she will deliver a litter of puppies approximately 63 days later. Sometimes there can be a ‘phantom’ or ‘false’ pregnancy, also known as pseudopregnancy, where the fluctuating hormones surrounding estrus and mating prepare the dog for pregnancy, even when fertilization hasn’t occurred.
Every time a dog goes through estrus, her cervix relaxes and opens, and the lining of the uterus thickens in preparation for mating and pregnancy. Ordinarily, the cervix helps prevent dirt, debris, and harmful bacteria from entering the uterus, so when the cervix is open, the risk of contamination and infection increases. If fluid and bacteria accumulate, infection can set in over the following 2-3 weeks, resulting in pyometra.
There are two types of pyometra: open and closed.
Open Pyometra
The more common and less dangerous of the two, an open pyometra occurs when there is infection in the uterus, but the cervix remains open. Dogs with an open pyometra are often diagnosed more easily because owners notice a foul-smelling discharge coming from the vulva, or that their dog becomes obsessed with licking her nether regions.
Because the pus can drain out of the uterus, an open pyometra tends to be less of a threat than one that is closed. However, an open pyometra can become closed, and vice versa.
Closed Pyometra
A closed pyometra occurs when the cervix has shut, locking infection inside the body. It is a far more dangerous situation because the problem is not always immediately obvious, and, as the infection continues, pus fills and stretches the uterus. This can bring a risk of septicemia (infection of the bloodstream) and uterine rupture, both of which carry a high risk of mortality.
What Are the Signs of Pyometra?
The signs of pyometra usually appear around 2-3 weeks after estrus. As mentioned above, dogs with an open pyometra may have a yellow, greenish, or brown discharge from the vulva which, if you get close enough to discover, smells pretty awful. However, dogs that are quite clean may lick up any discharge before you notice, so it’s important to be aware of the other signs of pyometra, which include:
What Are the Causes of Pyometra?
With each season a dog experiences, her risk of uterine infection increases. At each estrus, the cervix opens, and the repeated thickening of the uterine wall reduces its ability to contract and expel fluid and contaminants. Dogs over 7 years old are typically at higher risk, but pyometra can affect even young dogs.
The most common bacteria involved in pyometra is Escherichia coli (E. coli), responsible for around 90% of cases, usually from fecal contamination.1 Obesity, recessed vulvas, chronic diarrhea, and thick coats that regularly become soiled increase the incidence of fecal contamination of the vagina and uterus, putting dogs at a much greater risk for pyometra.
Studies have also shown that diet can affect the growth of pathogenic E. coli and therefore influence pyometra risk.2
The use of synthetic hormones to prevent embryo implantation or induce abortion in the case of accidental mating, or to suppress or delay estrus, has also been found to increase the risk of pyometra.3
How Is Pyometra Diagnosed?
Your vet will diagnose pyometra based on a combination of the history, clinical signs, and examination. They will usually perform a brief abdominal ultrasound. Pyometra appears as fluid inside the uterine horns, visible on ultrasound as discrete black circles or tubes.
Ultrasound of Pyometra
They will also perform some bloodwork to check for signs of septicemia and assess kidney function, hydration status, and rule out any other underlying issues.
How Is Pyometra Treated?
The fastest and most definitive treatment of pyometra is to perform an ovariohysterectomy – spay the dog.
The first step in treating pyometra is to start antibiotic therapy and intravenous fluids. Depending on the severity of the situation, your vet may recommend that your dog stay overnight on these treatments before proceeding with surgery, or they may want to go ahead right away.
Occasionally, mild cases of pyometra can be successfully managed using a combination of hormonal treatments and antibiotics. However, dogs that have had one episode of pyometra have a much higher chance of having another, which is why surgery is usually recommended. Once the ovaries and uterus have been removed, a dog can never get pyometra again.
Frequently Asked Questions (FAQs)
Can Pyometra Be Prevented?
Absolutely!
The surgical removal of the ovaries and uterus will completely eliminate the risk of pyometra. Dogs that are spayed earlier in life also have a significantly lower risk of mammary cancer.
In the last decade, advice regarding the timing of spaying has changed, and most vets recommend waiting until after the first season to ensure she has reached sexual maturity. For small breeds, the first season might occur at around 6 months, while for large or giant breeds, the first season may not happen until they are at least 12-18 months old.
What About Keyhole Spay?
In a keyhole or laparoscopic spay, only the ovaries are removed (ovariectomy); the uterus is left behind. This has become a popular option due to the perceived reduction in pain, discomfort, and recovery time. However, when performed on young, healthy dogs, the most challenging part of a routine spay is trying to convince the patient to stay quiet and calm after surgery!
Theoretically, by removing the hormonal factor, ovariectomy should prevent pyometra. However, in the case of ovarian remnant syndrome, where fragments of ovarian tissue are left behind, uterine infection can occur.
What If I Want To Breed My Dog?
Breeding from a dog that has (or has had) pyometra is not recommended. The circumstances that allow pyometra to form – open cervix, thickened uterine walls, contamination – can also make pregnancy riskier for the dog.
Additionally, pyometra can damage the uterine lining, reducing fertility and increasing pregnancy risks.
Shouldn’t I Let My Dog Have Puppies?
Before surgical spaying became common practice, allowing dogs to mate and have litters was likely seen as the best way to avoid pyometra. This is probably where the old wives’ tale that “you should let your dog have puppies” originated. These days, with millions of unwanted puppies in need of homes, and surgical sterilization being a relatively safe routine procedure, there is no longer any real justification behind the idea that dogs should have a litter.
What If I Can’t Afford Surgery?
If you think your dog might have a pyometra, do not delay treatment – the longer you wait, the worse things will get. If you are worried about costs, reach out to local charities or speak to your veterinarian – there may be payment plans or charitable funds available to help.
Is My Dog Too Old To Be Spayed?
A dog is never too old to get a pyometra, so even if your dog is considered elderly, unless they have health conditions that make surgery or anesthesia too much of a risk, it’s far better to have them spayed when they’re healthy rather than risk them getting a pyometra in old age.
Conclusion
Pyometra is a relatively common – and entirely preventable – disease in female dogs. Infection of the uterus can make your dog incredibly sick, and if left untreated, can even be fatal. Signs of pyometra usually appear 2-3 weeks after a season and include increased thirst & urination, lethargy, inappetence, fever, discomfort, and, in the case of an open pyometra, vaginal discharge.
If you suspect your dog may have pyometra, contact your vet immediately – do not delay.
If your dog hasn’t been spayed, talk to your vet. Remember, prevention is always better than cure.
Sources
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Dr. Karyn Kanowski, BVSc MRCVS (Vet)
Dr. Karyn is originally from Queensland, Australia, and has resided in the UK for the past 10 years. She graduated from The University of Queensland School of Veterinary Science in 2010, and also holds a Bachelor’s degree in Zoology. Karyn is passionate about using experience, evidence, and working with pet owners to provide the best solutions for pets. She also believes in making reliable information about animal health accessible to everyone. 5 cats and 4 dogs let her share their home with her and her husband, and when she is not practising as a veterinary surgeon, she spends her time writing, gardening, and cleaning up pet hair!
