As nouns the difference between dog and pyometra

is that dog is a mammal, canis lupus familiaris , that has been domesticated for thousands of years, of highly variable appearance due to human breeding while pyometra is (disease) an infection of the uterus most commonly seen in dogs, but also occasionally in other small mammals, resulting from hormonal and structural changes in the lining of the uterus.

As a verb dog

is to pursue with the intent to catch.