Demodicosis is an inflammatory skin disease in cats 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 a common infection in dogs, but rare in cats and when it does occur, it usually in cats who are immunocompromised or 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 develop demodicosis.
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.
Transmission occurs through direct cat to cat contact. Most cats remain asymptomatic, however, those who have a weak immune system can go on to develop clinical signs of demodicosis.
- Crusting: 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.
- Feline acne: Comedones (blackheads) develop on the chin. Inflammation and redness can occur.
- Hair loss: 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. Over-grooming can exacerbate this problem.
- Ear wax: A waxy secretion produced by the ears in response to mite infection along with comedones.
The veterinarian will be able to diagnose demodicosis from skin scrapings and ear swabs.
Mites can often be hard to find, and several scrapings from various parts of the body may be necessary. The mite can often be in fecal material when ingested during grooming.
Test all cats from the household, even if they are non-symptomatic.
Additional tests may be necessary to check for underlying immunosuppressive disease, this may include FIV and FeLV tests, biochemical profile, complete blood count, and urinalysis which can evaluate organ function.
Find and treat the underlying cause where possible as well as medications to kill the mite. Spontaneous remission may occur in untreated cats, especially those with localised demodicosis.
- Lime sulfur dips or shampoos for four to six weeks. Continue dips until skin scraping tests return negative.
- Amitraz is an insecticide which can kill the mites. This is toxic to cats, therefore use great care and closely monitor your cat.
Other treatments may include the following:
- Daily or weekly oral ivermectin for four weeks. It is important to monitor the cat during treatment.
- Wash bedding and blankets in very hot water, hang in the sun to dry.
- Treat all cats in the household.