Demodex mange (Demodex canis) in cats
Two species of mites cause disease in cats. Demodex cati is thought to be a normal inhabitant of feline skin. It is a follicular mite, similar to but narrower than the canine mite. The other species of Demodex (Demodex gatoi) is shorter, with a broad abdomen, and is found only in the stratum corneum. Feline demodicosis is uncommon.
In localized demodicosis, there are one or several areas of focal alopecia on the head and neck. In generalized disease, alopecia, crusting, and secondary pyoderma of the whole body are seen. The generalized form has also been associated with other systemic diseases, especially diabetes mellitus. In some cases, ceruminous otitis externa is the only clinical sign. Pruritus is variable; both species can cause similar disease, but cats infested with D. gatoi are more frequently pruritic.
Diagnosis is made by deep skin scrapings, although mite numbers are often small. Medical evaluation is indicated in cats with generalized disease. Dermatophyte cultures are essential, because dermatophytosis and demodicosis can be concomitant conditions. Prognosis of generalized demodicosis is unpredictable because of its potential relationship with systemic disease. Some cases spontaneously resolve. Weekly lime-sulphur dips (2%) are safe and usually effective; Amitraz (0.025-0.05%) has been used, but is not approved for use in cats and can cause anorexia, depression, and diarrhoea. The use of antiparasitic macrocyclic lactones (e.g. selamectin / ivermectin) has been reported but their efficacy is unclear.
   |
|
|
Demodex canis isolated from cat skin |