Mange is caused by a small oval mite that burrows beneath the skin of the animal and makes slender winding tunnels from 1/10 to nearly one inch long. Infested animals rub and scratch their bodies vigorously. Areas on the head, neck, or back, or at the base of the tail become inflamed, pimply, and scurfy, with the hairs bristling and only scattered hairs remaining. Later, the infestation may spread over the entire body, forming large, dry, cracked scabs on the thickened skin.
Excretions and the tunneling cause extreme pain, and animals often rub the area until it is raw. Within each tunnel, the female lays about 24 eggs, which hatch within 2 to 10 days. Mating occurs from 10 days to a month later. The males then die, and the females begin new tunnels. The problem is most evident in the winter, but some of the mites live on the animals year-round unless treated.
Mange mites, like lice, are permanent external parasites that do not survive away from the host for very long. The best way to minimize the risk of introducing the mites is to be cautious when buying or boarding new animals. Avoid any animals that show visible skin lesions or that appear to be abnormally itchy or agitated. Mites also can be transferred to horses from blankets and combs that were used on infected animals. Mange is contagious, and the most important control is the isolation and quarantine of infested animals. A veterinarian should be called if any of the animals show signs of unusual itchiness.
Several pesticides used for controlling cattle lice also are effective against chorioptic mange mites. Because of the severity of sarcoptic mange, it is regarded from a regulatory standpoint as a reportable disease. Therefore, the threshold for placing animals under quarantine is the discovery of a single mite.