Host animals scratch their ears excessively which causes loss of hair and scabbing. Secondary bacterial infections sometimes cause fever, depression and sullen, ill-tempered behavior. The ears of infected animals have a noticeable foul odor. Heavily infected animals often shake their heads constantly or run in circles in the direction of the most heavily infected ear. The most spectacularly bizarre behavior occurs when heavily infected dogs or cats are brought out of the cold into a warm room.
Symptoms tend to be less severe on older host animals.
Ear mites are passed from one animal to another when mites are dislodged during violent shaking of the head onto nearby animals or contact between animals, especially while nursing. However, it has been shown that ear mites also crawl about on the body of infested animals and that they can survive off of the host as long as hair and other detritus from the host animal are present. Thus, this mite passes from host to host with ease in confined quarters. Adult mites live about four weeks. Eggs hatch in 3 to 4 days and each active developmental stage lasts about one week and is followed by a 24 to 36 hour resting stage.