Boanthropy is a psychological illness that the person in pain behaves like a cow or ox.
It should be fairly easy to spot a patient suffering from boanthropy. He or she may well be down on all fours chewing grass. Boanthropy is a psychological disorder in which the sufferer believes he or she is a cow or ox.
The most famous sufferer of this condition was King Nebuchadnezzar, who in the Book of Daniel "was driven from men and did eat grass as oxen". Nebuchadnezzar was the king of the Neo-Babylonian Empire from 605BC to 562BC.
Nebuchadnezzar was humbled by God for boasting about his achievements, lost his sanity and lived like an animal for seven years, according to Daniel, chapter 4. When his sanity was later restored he praised and honoured God.
Aside from boanthropy, other explanations for his behaviour include porphyria (a group of enzyme disorders that manifest with neurological symptoms including hallucinations, depression, anxiety and paranoia) or general paresis or paralytic dementia caused by syphilis.