Cheyletiellosis, Walking Dandruff, Cheyletiella Mange

Cheyletiella mites affect dogs, cats, rabbits and, people. In people, the condition manifests as very itchy lesions on arms, trunk and buttocks. These lesions develop a central area of necrosis that is considered highly diagnostic. These mites are not associated with hair follicles (like demodex mites) and do not burrow (like sarcoptic and notoedric mites). They move rapidly on the surface of the skin in pseudotunnels of epidermal debris. They spend their entire life cycle on the host. Mites usually die within 48 hours off the host but, adult females have been maintained off the host for up to 10 days. Eggs are small and loosely attached to hairs. (Louse nits are much larger and are firmly cemented to hairs).

Causes of Cheyeletiellosis

Cheyeletiellosis is caused by Cheyletiella yasguri in dogs, Cheyletiella blakei in cats, and Cheyletiella parasitivorax in rabbits. Mites are not absolute host specific. The most common signs of Cheyletiella mange is pruritus (itching) which can vary from mild to moderate (not as intense as sarcoptic and notoedric manges) and dandruff along the back. Pruritus is primarily localized to the back but it can be anywhere on the trunk. Dry white scales (seborrhea), especially over the dorsum, and papules/crusts can also be present. In cats it can manifest as miliary dermatitis or symmetrical alopecia from excessive grooming. Cats can have pruritus without lesions and can be carriers of the parasites without developing clinical signs of the infestation.

Diagnosis of Cheyeletiellosis

Although definitive diagnosis is usually made by examining the mites with a microscope, a tentative diagnosis is often made based on the presence of mites and examination of the animal's skin. The mites and eggs are hard to find, especially on animals that are bathed often.

Treatment of Cheyeletiellosis

In many cases veterinarians will prescribe weekly dipping in an insecticide to eliminate the mites. Treatment should be repeated 6 to 8 times at weekly intervals. Amitraz dip weekly for 6 treatments is effective for dogs. Fipronil (Frontline flea spray): spray twice at two week intervals (dogs and cats). Treat all animals on the premises. The environment should be cleaned, sanitation improved, and the area thoroughly sprayed with a good residual insecticide every 2 weeks during the treatment period.

References:
1. Scott, Miller, Griffin: Parasitic Skin Diseases. In: Small Animal Dermatology, 5th ed., W.B. Saunders, Philadelphia, PA, 1995
2. Paradis, M., Vileneuve, A.: Efficacy of ivermectin against Cheyletiella yasguri infestation in dogs. Can. Vet. J. 29: 633, 1988
3. Paradis, M., et al.: Efficacy of ivermectin against Cheyletiella blakei in cats. J.Am. Anim. Hosp. Assoc. 26:125, 1990
4. McKee, J.W.: Recurrent infestation of a cat by Cheyletiella. eruditus (shrank 1781). Vet Rec.. 125:18, 1989.