The present report describes the clinical and pathological findings related to diffuse heterotopic hairs associated with pseudo-placentational endometrial hyperplasia in a canine uterus. Macroscopically, the uterus was intensely enlarged and thicker, and the endometrial surface was irregular and covered with black hairs similar to the hairs of the bitch. Histologically, heterotopic hairs associated with pseudo-placentational endometrial hyperplasia were observed.