How Common Is Pyometra in Dogs?

Pyometra, a pus-filled infection of the womb, is one of the most common serious illnesses in female dogs that haven’t been spayed.1Elsevier / Theriogenology. A breed-matched case-control study of potential risk-factors for canine pyometra For the owner of an intact female, it is a realistic risk over her lifetime rather than a rare emergency. How likely it is depends heavily on breed and age, and the risk climbs as a dog goes through more heat cycles. Almost every case can be prevented by spaying, which is why vets bring it up when owners are deciding whether to spay.

The Odds for an Unspayed Female Dog

In a large group of insured unspayed female dogs under 10, about 2 in every 100 developed pyometra in a single year.2Journal of Veterinary Internal Medicine. Breed Risk of Pyometra in Insured Dogs in Sweden Because that risk repeats through eight or nine years of heat cycles and rises with age, about 23–24% of these dogs had pyometra by age 10.3Journal of Veterinary Internal Medicine. Breed Risk of Pyometra in Insured Dogs in Sweden Other researchers describe the disease as affecting almost 25% of unspayed females before age 10.4Elsevier / Theriogenology. A breed-matched case-control study of potential risk-factors for canine pyometra

Roughly 1 in 4 intact females will face it before old age. The numbers stop at age 10, but the danger doesn’t: intact dogs older than that keep accumulating risk.

These figures come from insured dogs in Sweden, where far fewer dogs are spayed than in places like the US.5Journal of Veterinary Internal Medicine. Breed Risk of Pyometra in Insured Dogs in Sweden The share seen varies between countries and studies.6PubMed Central. Canine Pyometra: A Short Review of Current Advances So treat 1 in 4 as a solid ballpark for an intact dog rather than an exact forecast for yours. Spayed dogs are left out of these numbers because removing the womb removes almost all the risk.

The 1-in-4 figure is also an average across many breeds. A dog’s breed can push her risk well above or below it, so read it alongside the breed information below.

Which Breeds Get Pyometra Most

The gap between breeds is wide. The share with pyometra by age 10 ran from about 10% to 54%,10PubMed. Breed risk of pyometra in insured dogs in Sweden so in the highest-risk breeds, more than half of intact females may be affected by 10. In one group of Rottweilers followed through life, 6.6% were diagnosed, at a median age of about 5.4 years.11PubMed. Life course analysis of the impact of mammary cancer and pyometra on age-anchored life expectancy in female Rottweilers: Implications for envisioning ovary conservation as a strategy to promote healthy longevity in pet dogs

Differences between breeds suggest genes play a part.12PubMed. Breed variations in the incidence of pyometra and mammary tumours in Swedish dogs A possible gene link has been found only in Golden Retrievers, though, and experts say breed risk is not yet proven.13PubMed Central. Canine Pyometra: A Short Review of Current Advances

Most of these rankings come from Swedish data and may shift in other countries. A breed that is popular in one country may be rare in another, which changes what studies see. If you have a high-risk breed, bring it up with your vet when deciding whether and when to spay.

When in Life and in the Heat Cycle It Strikes

After each heat, the hormone progesterone thickens the womb lining and makes its glands produce more fluid.14vin.com. How Common Is Pyometra in Dogs? Meanwhile, bacteria from the vagina can travel up into the womb during heat, when the cervix is open.15PubMed. Cystic endometrial hyperplasia/pyometra in dogs: a review of the causes and pathogenesis In the weeks after heat, those bacteria can infect the primed womb.16PubMed. Cystic endometrial hyperplasia/pyometra in dogs: a review of the causes and pathogenesis Most often the germ is E. coli, the same kind of gut bacteria found in dog feces; it was found in 57–100% of cases.17PubMed Central. Characterization of Escherichia coli in Dogs with Pyometra and the Influence of Diet on the Intestinal Colonization of Extraintestinal Pathogenic E. coli (ExPEC)

Afterward the cervix closes again, sealing in anything that got through, inside a womb that progesterone has made welcoming. That explains why trouble shows up after the heat has ended. Age matters because each heat repeats the hormone effect on the womb, and the lining changes build up over years.18PubMed. Breed risk of pyometra in insured dogs in Sweden

Heat itself is not usually when signs appear. Trouble typically shows up roughly one to two months after heat ends. Mark heat dates on a calendar so you and your vet can connect symptoms to timing.

Pyometra is not caused by mating or by a male dog. The bacteria usually come from near the dog’s own genitals and gut, and the disease can affect dogs that have never been near a male.

Other Things That Raise or Lower Risk

Females that have never had a litter are at higher risk than those that have.19PubMed. Associations between age, parity, hormonal therapy and breed, and pyometra in Finnish dogs In one clinic group, about 7 in 10 dogs with pyometra had never had puppies.20World’s Veterinary Journal. Contributing Factors and Management of Pyometra in Dogs of Algeria But a previous pregnancy seemed protective in Rottweilers, Collies and Labradors, and not in Golden Retrievers.21PubMed. A breed-matched case-control study of potential risk-factors for canine pyometra So it isn’t a rule that holds for every dog. Breeding a dog brings its own risks, so it is not a health measure to choose.

Hormone drugs matter too. Progesterone-like drugs used to delay or stop heat made closed pyometra almost 5 times more likely.22PubMed Central. Microbiological and hematological aspects of canine pyometra and associated risk factors These drugs mimic progesterone, close the cervix and weaken the womb’s defenses.23PubMed Central. Microbiological and hematological aspects of canine pyometra and associated risk factors Estrogen shots given to prevent pregnancy after an accidental mating can also set the stage for pyometra.24dvm360. Canine pyometra: Early recognition and diagnosis Ask your vet about pyometra risk before any heat-control or mismating drug.

Diet may play a role as well. The E. coli strains found in an infected womb often match those in the dog’s own gut, and diet may influence which strains settle there. This is an early finding, not a proven way to prevent pyometra.

Signs to Watch For and How Dangerous It Gets

In open pyometra, the cervix stays open and pus drains as a foul vaginal discharge. In closed pyometra the cervix is shut, so pus builds up inside with no visible discharge. In one group, more than half of closed-cervix dogs were moderately or severely depressed, compared with 30% of open-cervix dogs.25PubMed Central. Closed cervix is associated with more severe illness in dogs with pyometra Another study found open cases more often showed vomiting, dehydration and dullness.26Journal of Veterinary and Animal Sciences. Comparative analysis of closed and open cervix canine pyometra Either type can make a dog very ill.

At home, look for tiredness, poor appetite, vomiting, heavy drinking and frequent urination. A sticky, smelly discharge from the vulva points to the open form. A swollen belly with no discharge can mean the closed form. Extra licking of the rear end can hide a discharge.

Dogs hide illness, so early pyometra can look like a dog who is simply quieter than usual. The signs overlap with many other illnesses, so timing after a heat is an important clue, though only a vet exam and tests can confirm pyometra.

The infection doesn’t stay in the womb. Many dogs develop sepsis, a body-wide reaction to the infection: nearly 6 in 10 in one study.27PubMed. Cytokines as immunological markers for systemic inflammation in dogs with pyometra Pyometra can also strain the kidneys, causing protein loss in urine,28PubMed. Evaluation of kidney injury in dogs with pyometra based on proteinuria, renal histomorphology, and urinary biomarkers though this is often temporary after treatment.29Journal of Veterinary Internal Medicine. Escherichia coli Pyometra Induces Transient Glomerular and Tubular Dysfunction in Dogs In about 3% of surgical cases the womb had already burst.30PubMed. Findings and prognostic indicators of outcomes for bitches with pyometra treated surgically in a nonspecialized setting

Any of these signs in an intact female weeks after a heat is an emergency. Don’t wait to see if it passes, since closed cases can worsen within days. Tell the vet when her last heat was and about any hormone drugs she has had.

Treatment and Survival

The usual treatment is an emergency spay, which removes the infected womb and ovaries. The dog is usually stabilized first with fluids and antibiotics, since a very sick dog needs support before anesthesia. The surgeon takes care removing the womb because it can be fragile, and a burst womb would spill infection into the abdomen. Afterward she stays in the hospital, then rests at home with medication while the incision heals.

Survival is good. In ordinary vet clinics, 97% of dogs treated this way survived to go home.31PubMed. Findings and prognostic indicators of outcomes for bitches with pyometra treated surgically in a nonspecialized setting Another study saw only 1% die after surgery, lower than the 5–27% in older reports.32PubMed Central. Outcome of pyometra in female dogs and predictors of peritonitis and prolonged postoperative hospitalization in surgically treated cases Recovery can still be long: almost half stayed in the hospital two nights or more.33PubMed. Findings and prognostic indicators of outcomes for bitches with pyometra treated surgically in a nonspecialized setting Dogs with high kidney blood values or a heart murmur were more likely to die.34PubMed. Findings and prognostic indicators of outcomes for bitches with pyometra treated surgically in a nonspecialized setting

Stable dogs meant for breeding can sometimes be treated with drugs that block progesterone instead of surgery. This healed about 93% of dogs within three weeks in one group,35PubMed. Follow-up examinations of bitches after conservative treatment of pyometra with the antigestagen aglepristone but about 19% relapsed within a year.36PubMed. Follow-up examinations of bitches after conservative treatment of pyometra with the antigestagen aglepristone In another group, nearly half relapsed over up to six years.37PubMed. A retrospective study of bitches with pyometra, medically treated with aglepristone Many treated dogs went on to have puppies,38PubMed Central. Fertility outcome after medically treated pyometra in dogs so drug treatment keeps breeding possible but leaves risk behind.

Dogs treated with drugs are usually advised to be bred soon and spayed afterward. Cysts on the ovaries or womb make relapse more likely, so ask about scans.

What Pyometra Treatment Costs

Private vet practices typically charge about $600 to $2,500 for pyometra surgery.39Elsevier / PubMed Central. Pyometra Management Practices in the High Quality, High Volume Spay-Neuter Environment Emergency hospitals typically charge about $1,500 to $3,579.40Elsevier / PubMed Central. Pyometra Management Practices in the High Quality, High Volume Spay-Neuter Environment Some high-volume, low-cost spay clinics charge a median of about $200,41Elsevier / PubMed Central. Pyometra Management Practices in the High Quality, High Volume Spay-Neuter Environment and a routine planned spay usually costs far less than emergency pyometra care.

Price depends on the type of hospital, the dog’s size and how sick she is on arrival. A dog already in sepsis needs more intensive care, fluids and monitoring, which raises the total. Costs also vary by region, so these ranges are a guide for comparison rather than a quote for your dog.

If cost is a worry, ask your local low-cost clinic whether it treats pyometra cases. Pet insurance must usually be in place before illness begins. When deciding about spaying, compare a routine spay price with the emergency ranges.

Spayed Dogs and Cats Can Rarely Get It Too

A spayed dog can rarely develop an infection in a small piece of womb tissue left after surgery. A spay is meant to remove the whole womb, but a small piece can remain, and that remnant can respond to hormones. In one reported case, a spayed Chihuahua developed it after a year of contact with an owner’s estrogen spray.42PubMed. Stump Pyometra Secondary to Human Topical Estrogen Hormone Exposure in a Spayed Female Chihuahua Tamoxifen, a cancer drug, acts like estrogen in the womb and caused pyometra in intact dogs after about 90 days.43PubMed Central. Stump pyometra in a spayed female dog secondary to tamoxifen So keep human hormone creams and sprays away from your dog’s fur and skin.

Signs of estrogen exposure include a spayed female suddenly showing heat signs such as a swollen vulva, discharge or attention from male dogs. Tell your vet about any hormone gel, cream or spray used at home, and wash your hands after applying hormone products before petting your dog.

Cats can get pyometra too, but it’s less common.44Clinical Theriogenology. A review of pyometra in small animal medicine: incidence, pathophysiology, clinical diagnosis, and medical management Cats only ovulate after mating, so their wombs get less progesterone exposure.45Clinical Theriogenology. A review of pyometra in small animal medicine: incidence, pathophysiology, clinical diagnosis, and medical management One vet reported about one cat case for every three dog cases.46Clinical Theriogenology. A review of pyometra in small animal medicine: incidence, pathophysiology, clinical diagnosis, and medical management