I’ve seen a veritable epidemic of womb infections in older dogs during the month of September. I treated five cases, which for a new clinic is a really high number. Pyometra infection in dogs is caused by the hormone progesterone acting on the unspayed uterus. The uterus is a hollow organ which can fill up with infected pus. This is a life threatening emergency. It can cause serious sequelae such as kidney failure, shock and sepsis. If you’re not breeding your dog, our advice is to get her neutered when she’s young, fit and healthy.