Dorsal scales: Cheyletiellosis in a German Sheppherd
Cheyletiellosis in a German Sheppherd
Cheyletiellosis in a rabbit

Cheyletiellosis is a dermatosis (skin disease) caused by a mite of the family Cheyletidae. It is often underestimated and sometimes causes serious problems. Cheyletids are large (450-500µm), scale-eating or dust mite predators.

Several species are observed in animals:

  • Cheyletiella blakei in cats
  • Cheyletiella yasguri in dogs
  • Cheyletiella parasitovorax in rabbits.

However, there is no species specificity which allows both dog (C. yasguri) and rabbit (C. parasitovorax) cheyletiella to affect a cat. These parasites live on the surface of the skin and feed on skin debris. The environment is an important source of infestation as these parasites can survive 1 month outside the host. Cheyletiellosis is enzootic in some farms.

The clinical signs of cheyletiellosis are abundant squamosis affecting mainly the head and trunk. Excoriations (small sores on the surface of the skin), areas of alopecia and miliary dermatitis (in cats only) are also observed.  Pruritus (itching) can be intense and discrete.

Human contagiousness is frequent (20 to 80% of humans in contact) especially if the contacts with the infested animal are close. The lesions are located in areas of the body that come into contact with the infected animal. The dermatitis is characterised by intense pruritus and pruritic papules, either single or in groups of 3. These lesions rapidly become vesicular, pustular, crusted and often develop a central necrotic area. Humans constitute a parasite dead end because cheyletids do not reproduce on their skin.

Diagnosis is based on microscopic evidence of the parasites collected by the scotch test, skin scraping or brushing technique.

The treatment of affected animals involves the regular use of external antiparasitics in the form of sprays or spot on.
Treatment of the environment is essential. This consists of cleaning the premises and burning contaminated material and the use of residual acaricides or disinfectants to control reinfestation by the environment. A sanitary vacuum of 2-3 weeks is also recommended in affected farms.

Copyright Dr Luc Beco

Dorsal scales on the back of a rabbit suffering of cheyletiellosis