Pyometra in Dogs

What Is Pyometra in Dogs?

Pyometra is a serious uterine infection in unspayed female dogs. It often develops after a heat cycle, when hormonal changes allow bacteria to multiply in the uterus. The infection causes the uterus to fill with pus and can rapidly become life-threatening if left untreated.

There are two types of pyometra:

Open pyometra: Pus drains through the vulva, making it easier to detect.
Closed pyometra: The cervix remains sealed, trapping infection inside. This form is more dangerous and harder to catch early.

Causes and Risk Factors of Pyometra in Dogs

Pyometra is caused by a mix of hormones and bacteria. During oestrus, progesterone levels rise, thickening the uterine lining. If the dog doesn’t become pregnant, repeated cycles can create a perfect environment for bacterial growth.

Common risk factors include:

Age (usually over 5 years old)
Repeated heat cycles without pregnancy
Hormone-based treatments (e.g. misused oestrus suppressants)
Breeding history and uterine scarring

Signs of Pyometra in Dogs

Early signs may be subtle. Breeders and pet owners should watch for the following:

Vaginal discharge (pus or blood-streaked fluid)
Swollen or tender abdomen
Lethargy or unwillingness to eat
Fever
Vomiting or diarrhoea
Frequent urination
Drinking more water than usual

With closed pyometra, no discharge may be visible. Any unusual signs after a heat cycle should be treated as urgent.

Why Pyometra Is a Breeder Concern

For breeders, pyometra doesn’t just threaten the health of one dog, it can cause long-term fertility damage.

If a dam develops pyometra:

Future litters may not be possible
Emergency surgery may result in spaying
There’s a risk of sepsis, shock, or even death
Veterinary costs can be significant

Being proactive protects both your animals and your reputation.

Diagnosis and Treatment of Pyometra in Dogs

Vets typically diagnose pyometra through a combination of:

Physical examination
Bloodwork to check for elevated white cell counts
Ultrasound or X-rays to confirm an enlarged, pus-filled uterus

Treatment options:

Emergency surgery (ovariohysterectomy): Most common and often life-saving
Medical management: Only used in select cases for breeding dogs with open pyometra and no complications

Even with successful treatment, future fertility is not guaranteed. Most vets recommend retiring a dog from breeding after pyometra.

How to Prevent Pyometra in Dogs

Responsible breeders take early action to prevent this condition, especially in dogs not yet retired from breeding.

Here’s how:

Track heat cycles carefully
Avoid unnecessary hormone treatments
Don’t delay mating season after season—repeated cycles without pregnancy increase risk
Retire dogs from breeding at an appropriate age
Consider elective spaying for non-breeding females

RPBA Supports Breeder Health Education

At Responsible Pet Breeders Australia, we equip members with resources to recognise early warning signs, work with trusted vets, and reduce health risks across generations.

Included with membership:

Breeding health checklists
Whelping and postpartum care guides
Heat cycle and weight tracking templates

Protect Your Dogs, Protect Your Breeding Program

Pyometra in dogs is preventable when you know the signs and act early. As an RPBA member, you’ll never be left guessing when it comes to your dogs’ health. Not yet a member? Join RPBA to access breeder tools, health guides, and a community that puts animal welfare first.