Pyometra in Dogs: A Life-Threatening Uterine Infection

By Tailwisp Editorial TeamUpdated October 17, 20263 min read

Pyometra is one of the reasons many vets recommend spaying: it can kill a healthy-looking dog within days.

What it is

After each heat, hormonal changes thicken the lining of the uterus. Over repeated cycles, this can lead to cystic changes and bacteria entering, causing a pus-filled infection. Toxins enter the bloodstream and can cause kidney failure, sepsis and death.

Who is at risk

Unspayed females, especially those over four years old, but any intact female can develop it. It usually appears one to three months after a heat. Dogs given hormone drugs are also at higher risk.

Open versus closed

• Open pyometra: the cervix is open, and pus drains from the vulva, often smelly and bloody. Owners notice it sooner.
• Closed pyometra: the cervix is closed, pus accumulates inside, the belly swells and the dog can become critically ill with little visible discharge.

Signs

• Increased thirst and urination. See excessive thirst and urination in dogs
• Lethargy and weakness
• Loss of appetite
• Vomiting and diarrhea
• Vaginal discharge with pus or blood and a foul smell
• Swollen abdomen
• Fever or low temperature
• Excessive licking of the vulva
• Collapse and shock in severe cases

Emergency

Go to the vet immediately if an unspayed female has these signs after a heat. Pyometra can progress rapidly. See dog emergency warning signs.

Diagnosis

Vets use an exam, bloodwork, urinalysis, X-rays or ultrasound to detect an enlarged, fluid-filled uterus. Bloodwork shows high white blood cell counts and often kidney changes.

Treatment

• Emergency spay (ovariohysterectomy) to remove the infected uterus is the standard treatment
• Intravenous fluids and antibiotics before and after surgery
• Pain relief and monitoring
• Medical management with drugs like prostaglandins and antibiotics in rare, selected cases of valuable breeding dogs, with risks and a high chance of recurrence

Surgery on a sick dog carries higher risk than a routine spay, but delay is more dangerous.

Recovery

Dogs usually improve quickly after surgery but need hospital monitoring and recovery care. See dog spay recovery.

Prevention

Spaying before the first or second heat essentially eliminates the risk. For breeding dogs, spay after the breeding career ends. See spay and neuter pros and cons.

Stump pyometra

Rarely, a spayed dog can develop infection in a remnant of uterine tissue left behind, called stump pyometra. See your vet if a spayed female has discharge or illness signs.

Questions to ask your vet

Ask about your dog's risk, when to spay if she is intact, what signs to watch after every heat and which clinic handles emergencies.

Common mistakes

• Waiting to see if she improves
• Assuming no discharge means no infection
• Delaying spay in older intact females
• Using home remedies

Troubleshooting

• My dog is drinking a lot after heat: call your vet today.
• She has discharge and seems fine: still call.
• Her belly looks swollen: go to the vet immediately.

A simple plan

1. Know the signs.
2. Act fast.
3. Choose emergency surgery.
4. Prevent with spaying.

Real-life examples

A spaniel with a foul discharge has an emergency spay and recovers. A retriever with a closed pyometra becomes critically ill and survives after surgery. A terrier spayed young never faces the risk. Prevention works.

Know the risk

Any intact female should be watched closely after each heat.

Costs and decisions

Emergency surgery costs more than a planned spay, and the decision is time-critical. Ask for an estimate, discuss payment options and consider pet insurance in advance. Because delay raises risk sharply, most vets recommend surgery as soon as the dog is stabilized, unless a specialist advises otherwise for a breeding animal.

After surgery

Expect a night or two in hospital with fluids and antibiotics, followed by a recovery plan at home with a cone, restricted activity and rechecks. Report any vomiting, lethargy, discharge or swelling immediately, since complications such as peritonitis and kidney problems can still develop in the days after surgery.

The takeaway

Pyometra is life-threatening, and spaying is the best prevention. Seek care immediately for signs after a heat.

This article is general educational information, not veterinary advice. Every dog is different. If your dog is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.