[Demodicosis of dogs--a factorial disease?]

Abstract

Demodex canis is a normal resident of the intact canine skin, being present in small numbers in virtually every dog. Most animals are only carriers of the mites and do not develop clinical symptoms, therefore, demodectic mange has already to be considered as a factorial disease. The modus operandi of transition of clinically inapparent colonization of the mites into a disease may be explained according to investigations so far published multifactorially and thereby essentially as consequences of primary or secondary immunodepression. A primary immunodepression is initially based most probably on a hereditary defect of T-cells and is subsequently reinforced by substances, which are presumably synthesized and liberated not only by mites but also by secondary bacterial agents. A secondary immunodepression operates as trigger mechanism of a clinical manifestation after corticosteroid or cytostatic therapy or in course of underlying diseases of potentially immunodepressive nature, i.e., malignant neoplasia, hepatopathies, hyperadrenocorticism and lymphosarcoma.