Pyometra is a common disease in intact bitches and queens and occurs, although less frequently,in most other female pets. The illness is generally diagnosed within 4 months after estrus, in middle-aged to older bitches and queens. Hormonal and bacterial factors are important for the disease development, and progesterone plays a key role. The diagnosis is based on case history, clinical signs, and findings on physical examination, laboratory analyses and diagnostic imaging. Pyometra is potentially life-threatening and considered a medical emergency. Surgical ovariohysterectomy is the safest and most efficient treatment, but purely pharmacologic options are possible in less severe cases.