Pyometra is an infection in the uterus that is the result of structural and hormonal changes in the uterus lining, primarily in unaltered female dogs. It is possible however for humans to have the disease as well as female cats, rabbits, hamsters, ferrets, rats and guinea pigs. As a pet owner it is important to know the sudden nature of this disease and the deadly consequences if it is left untreated. It can happen at any age whether the female has been bred or not, but it is most common in dogs as they get older. The main risk period is the eight weeks following her peak estrous “heat” cycle, whether it is her first or her tenth cycle. Spaying is the best way to prevent pyometra. Treatment will require aggressive intravenous fluids and antibiotics because the dog is generally septic and in shock. Once she is stabilized an emergency spay must be performed..