You searched for: “zoanthropic
zoanthropic (adjective) (not comparable)
Descriptive of a mental disorder in which people believe themselves to be animals: Timothy had the vision that he was a beast, or other creature, and after his doctor examined him, he said that he was suffering from a zoanthropic deception.

A zoanthropic psychotic belief is a kind of monomania, or delusion, in which patients are convinced that they have been transformed into one of the lower animals.