Generalised demodicosis and doramectin

Demodex canis mites are normally found inside the hair follicles of healthy dogs and demodicosis results from an abnormal and excessive proliferation of these organisms. Young dogs affected by this disease tend to show a genetic predisposition linked to poor immune response, while predisposing factors in older dogs include the administration of immunomodulatory drugs and other underlying diseases such as leishmaniosis, hypothyroidism, hyperadrenocorticism and neoplasia.

For the first time, a recent study compared the efficacy of two different treatment protocols using doramectin, a drug that is currently recommended for the treatment of generalized demodicosis.

Twenty nine dogs were distributed into two groups. Sixteen dogs received 600 µg/kg of subcutaneous doramectin once a week and the same dosage was administered orally to the other thirteen dogs. Both protocols had high success rates (81% and 92%, respectively) and presented a similar response time, obtaining negative skin scrapings between 12 and 13 weeks from the start of treatment.

Although other papers have mentioned ataxia and a localized reaction at the site of subcutaneous injection of doramectin, no side effects were observed in this study. Only cases achieving complete remission with no recurrence of clinical signs for a year after the last administration of doramectin were considered for this research.

In Cordero, A. M., Quek, S. and Mueller, R. S. (2018), Doramectin in the treatment of generalized demodicosis. Vet Dermatol, 29: 104-e41. doi:10.1111/vde.12515