What is pyometra?

Pyometra is a severe, life-threatening infection of the uterus that develops in unspayed female dogs and cats. The condition occurs when bacteria invade the uterine lining, usually within weeks following a heat cycle. The infected uterus fills with pus, and without treatment, the infection spreads into the bloodstream, causing sepsis and organ failure.

The disease has two forms. Open-cervix pyometra allows pus to drain through the cervix, producing vaginal discharge that owners may notice. Closed-cervix pyometra is more dangerous because pus accumulates inside the uterus with no outlet, building pressure and toxicity rapidly. Affected animals show lethargy, loss of appetite, fever, excessive thirst and urination, and abdominal pain. Some females appear acutely ill within days, while others decline gradually over weeks.

Diagnosis requires physical examination, bloodwork showing infection markers, and abdominal ultrasound or X-rays to confirm uterine enlargement and fluid accumulation. Treatment is emergency surgery to remove the infected uterus and ovaries, along with IV fluids, antibiotics, and supportive care. Survival rates are high with prompt surgery, but delay risks rupture, peritonitis, and death. Spaying prevents pyometra entirely, making it a key reason veterinarians recommend early spaying for female pets. Any unspayed female showing these signs needs immediate evaluation at an emergency veterinary clinic.