My cat’s vulva is swollen and now oozing pus after being out—what could it be?

Swelling and pus at a female cat’s vulva may be pyometra, usually with worse spirits and appetite, and needs prompt ultrasound and surgery at a clinic. If the cat is still lively and eating well and shows clear discharge, it may be estrus or pregnancy; normally a cat in heat shows almost no discharge, unlike dogs with menstrual bleeding, but a few cats in intense heat or stimulated by a male outside may show clear fluid at the vulva, so the owner should carefully judge the discharge color and the cat’s condition.