Hot Literature: Managing canine demodicosis: Practical guidelines for all practitioners


Hot Literature: Managing canine demodicosis: Practical guidelines for all practitioners

Jul 01, 2012

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Guidelines for the diagnosis and treatment of canine demodicosis—assembled by an international group of veterinary specialists—are now available to all veterinarians. The purpose was to provide veterinary practitioners with a straightforward description of diagnostics and treatment options in dogs with either localized or generalized demodicosis and to address the differences between juvenile- and adult-onset demodicosis. The recommendations do not take into account availability or label indications of the therapeutics for specific countries or products.


Characterizing the condition as local or generalized is important because localized forms carry a good prognosis—with most cases spontaneously resolving—while generalized cases pose more treatment challenges and garner the recommendation for neutering to prevent the breeding of these animals. The committee defines localized disease as consisting of no more than four lesions with a maximum diameter of 2.5 cm.


In cases of juvenile demodicosis, Demodex species mites are transmitted to pups from the bitch, but it is thought that a problem with the immune system is necessary to allow these mites to proliferate and cause disease. Anything resulting in debilitation such as malnutrition or endoparasitism could be at the root. In adults, any disease condition that can compromise the immune system may permit the development of demodicosis. However, a cause-and-effect relationship has not been found since many immunocompromised individuals never develop demodicosis.


The forelimbs and face are often affected first, but the lesions can progress to other sites. Mild disease is marked by comedones and scaling, with partial or complete alopecia. Multiple coalescing areas of alopecia and follicular papules indicate moderate disease. More advanced or severe disease is characterized by pustules, furunculosis with scales, crusts, exudation, and ulceration. Draining tracts and nodules can also occur in advanced demodicosis. Secondary pyoderma is a common consequence, and bilateral otitis externa may also occur. In generalized cases, affected dogs may even become lethargic and febrile.


Identifying Demodex species mites on examination of multiple deep skin scraping samples is the preferred method of diagnosis. Occasionally, mites may be found via trichograms from areas of the body that may be difficult to scrape; skin biopsies are rarely necessary. The guidelines detail the procedures for obtaining diagnostic-quality skin scrape and trichogram samples and examining them for mites.

Whenever possible, perform cytology along with bacterial culture and sensitivity. To optimize therapeutic response, diagnose and treat underlying or predisposing factors.