A recent issue of the Dutch journal Tijdschrift voor Psychiatrie
(Journal of Psychiatry) reports on the case of a woman who believed she was a chicken. From the report (via Google translate):
Patient A, a 54-year-old woman, consulted the emergency department with her brother for acute attacks of deviant behavior, expressing the belief that she was a chicken and displaying behavior reminiscent of it.
Clinically, we saw a lady profusely sweating, trembling, blowing her cheeks and displaying stereotypical behavior in which she seemed to imitate a chicken, such as clucking, cackling and crowing like a rooster. After ten minutes, she seemed to tense the muscles for a few seconds, her face flushed and she did not respond for a short time. These symptoms repeated at intervals of several minutes, between which anamnesis was possible. The patient's consciousness was fluctuating, attention was hyper-reactive and the patient was disoriented in time and space. Her memory could not be tested objectively, but she could adequately tell her history.
She said she had barely slept since five days and wandered barefoot and dressed in a dressing gown on the street at around 4 a.m. the previous night. A general feeling of unwellness had been present for several days, as well as a strange feeling in the limbs, as if they no longer fit her body and flapped uncontrollably. The patient expressed the thought of being a chicken and that they had been forgotten to roost her.
Patient's brother added that he found her in the garden in the same condition as we saw her now. Between that moment and the registration with us, the bizarre behavior in attacks occurred.
The researchers note that clinical zoanthropy (the belief that one has turned into an animal) is an extremely rare delusion. Apparently there have been only 56 cases of this reported between 1850 and 2012. Some of the animals people believe they have become include "a dog, lion, tiger, hyena, shark, crocodile, frog, bovine, cat, goose, rhinoceros, rabbit, horse, snake, bird, wild boar, gerbil and a bee."
More info: The Guardian