A 10-year-old female Fox Terrier was admitted to the Stange Memorial Clinic on June 23, 1944. The history presented was that of a growth on the mammary gland which had been slowly enlarging. The dog's general condition appeared good; however, there was an enlargement in the left inguinal and posterior region. The enlargement extended from the immediate inguinal region to within 2 cm. posterior to the umbilicus. There was some deep fluctuation indicating the presence of an abscess. A diagnosis of neoplasm of the mammary gland with abscessation was made.