On April 4, 1940, a Boston Terrier bitch, two years of age was presented at the Iowa State Clinic with a history of having had a vaginal discharge since her last estrus period in December. This discharge was quite copious and of a muco-purulent type. On the day of entrance her temperature was 102.2°, respiration 58, and pulse 140. After an examination with a vaginal speculum a diagnosis of pyometra was made. A hysterectomy was indicated.