Asian bull elephant (Elephas maximus) in musth. Bull elephants periodically enter a condition known as musth. It is characterised by extremely aggressive behaviour, increased testosterone levels, swelling of the temporal glands in the head causing considerable pain, and discharge of a secretion called temporin from the temporal ducts on the sides of the head. The condition seems to be linked to sexual arousal or establishing dominance, and can last from several weeks to some months. The Asian or Asiatic elephant is found in Southeast Asia from India in the west to Borneo in the east. It is an endangered species.