Topical (pour-on) ivermectin in the treatment of chronic generalized demodicosis in dogs.

Twelve privately owned dogs with chronic generalized demodicosis were treated topically along the dorsal midline with 1.5 mg kg of 0.5% pour-on ivermectin for cattle three times per week for 3-6 months. All 12 dogs had a substantial reduction in clinical signs and in the number of Demodex canis mites found on skin scrapings. Only two dogs, however, became skin-scrapings negative after 3 and 5 months of treatment, respectively. In these two dogs treatment was prolonged for an additional 4 weeks past the negative scrapings. One dog relapsed 2 months after cessation of therapy; the other is still free of symptoms 1.5 years later. The cure rate, based on the lack of recurrence of clinical signs for 12 months after discontinuation of ivermectin administration, was 1 of 12 dogs (8%). Adverse reactions were not seen.