zoanthropy \ zoh-AN-thruh-pee \ , noun;
1.Psychiatry . a mental disorder in which one believes oneself to be an animal.
Quotes:
In his book Wolf Child and Human Child , Arnold Gesell gives a striking account, based on the original source material, of the misfortunes of Amala and Kamala, the two best known cases of zoanthropy .
-- Lucien Malson and Jean Marc Gaspard Itard, "Wolf Children and the Problem of Human Nature ," 1972
A zoanthropian, Orion, who was possessed by zoanthropy , had been an enemy. He believed himself to be a roc, marrying one.
-- Willis Bryant, "Cold Blood ," 2012
Origin:
Zoanthropy came to English in the mid-1800s from the New Latin zōanthrōpia based on the Greek ánthrōpos meaning "human being, man."
Dictionary.com