Mange mite – Coyotes may be a host for the itch or mange mite. Female mites can burrow into the skin.
Coyotes with mange can lose their hair, which can make it difficult for them to control their body temperatures.
Mange must be extremely severe before it disables a coyote. Most coyotes can survive with the disease for a long time.
source: http://www.azgfd.gov/w_c/urban_coyote.shtml