Canine demodicosis: a retrospective study of a veterinary hospital population in California, USA (2000-2016).

Background: Demodex spp. are cutaneous mites that cause clinical disease when present in increased numbers. There is an association in some dogs with underlying systemic disease or immunosuppressive medications.

Hypothesis/objectives: Retrospective study to document breed predisposition, identify any concurrent diseases or underlying immunosuppressive conditions, and to determine the frequency of demodicosis recurrence after treatment completion.

Animals: There were 431 dogs with demodicosis presented to a veterinary teaching hospital in California, USA, from 2000 to 2016.

Methods: Inclusion in this study required a diagnosis of demodicosis based on direct demonstration of the mite. Records were reviewed for signalment, disease history, potential underlying aetiologies, diagnosed concurrent diseases, medications and demodicosis treatment. Analyses were performed to evaluate for potential breed predispositions and because of the large number of dogs with allergic dermatoses, analyses for this diagnosis as a disease associated with demodicosis was also performed. E-mailed surveys and follow-up telephone calls were used to assess for information about disease recurrence.

Results: The pit bull terrier group and West Highland white terrier, based on calculated odds ratio, were breeds predisposed to developing demodicosis. For dogs with demodicosis, allergic dermatoses was an associated disease. Relapse or recurrence of disease after treatment was uncommon, affecting 11% of the dogs with long-term follow-up.

Conclusions/clinical Importance: This study identified, in dogs attending the institution based in California, USA, breed predilections for canine demodicosis and associated concomitant diseases. It also revealed a low occurrence of disease relapse, recurrence or persistence.