Demodicosis is a skin disease caused by the Demodex mite. There are two species, Demodex cati and Demodex gatoi which infect cats.
- Demodex cati is long and slim, living within the hair follicles.
- Demodex gatoi is shorter, living within the surface layers of your cat's skin.
Demodicosis is quite common in dogs, but rare in cats and when it does occur, it is usually seen in cats who are immunocompromised or who are malnourished. Diseases such as diabetes, hyperadrenocorticism (Cushing's syndrome), feline leukemia virus, feline immunodeficiency virus and use of immunosuppressive drugs can all predispose your cat to developing demodicosis. Demodicosis may be localised (one or several small patches) or generalised (over a larger part of the cat's body).
The life cycle of these mites is 20-35 days and is spent entirely on the host. There are no age, sex or breed predilections. It can be transmitted from cat to cat through direct transmission but not cat to human. Most cats remain unsymptomatic, however those who are immunosuppressed can go on to develop clinical signs of demodicosis.
What are the symptoms of demodicosis in cats?
- Single or multiple areas of alopecia with crusting and scaly looking patches of skin on the balding areas. The head, ears and neck are most commonly affected areas, but it can occur elsewhere.
- Generalised demodicosis may also occur with large areas of symmetrical thinning of the hair or alopecia along with patchy areas on the head, neck and ears and crusting, fluid filled sores.
- A waxy secretion may be be produced by the ears in response to mite infection along with comedomes.
- Cats may overgroom, resulting in widespread hair loss.
How is it diagnosed?
Diagnosis of demodicosis is made by skin scrapings and swabs from the ears which are examined under a microscope. Mites can often be hard to find, and several scrapings from various parts of the body may be necessary. The mite may also be found in fecal material due to ingestion via grooming.
Non symptomatic cats from the same household should also be tested.
Additional tests may be necessary to check for underlying immunosuppressive disease. This may include FIV and FeLV tests, complete blood count, biochemical profile and urinalyais which can evaluate organ function.
How is it treated?
Spontaneous remission may occur in untreated cats. Especially those with localised demodicosis.
Lime sulfur dips or shampoos for four to six weeks. Dips should be continued until skin scraping tests return negative.
Amitraz may also be used, but this is toxic to cats and great caution should be used.
Other treatments may include daily or weekly oral Ivermectin for four weeks, however this is not approved for use in cats and there is a risk of side effects.
Treating or managing the underlying cause (if one is found).
All cats in the household should be treated and bedding washed in very hot water and hung out in the sun to dry.