Objective: To determine the efficacy of increased dosages of milbemycin oxime in the treatment of generalized demodicosis.
Design: Prospective clinical trial.
Animals: 26 adult dogs with chronic generalized demodicosis.
Procedure: In phase 1, milbemycin was administered daily to 13 dogs at an approximate mean dosage of 1 mg/kg of body weight (PO) until 30 days after skin scrapings failed to detect mites. If the mite count had not decreased by 25% from the prior month's examination, the drug dosage was increased to approximately 2 mg/kg. Treatment was considered a failure if the mite count had not changed on 2 successive examinations. In phase 2 involving 13 other dogs, an approximate mean dosage of 2 mg/kg was used. If mite counts had not been reduced to 0 by 180 days, treatment was considered to have failed.
Results: In phase 1, when milbemycin was administered at the initial low dosage, 6 dogs were considered to have been cleared of mites. One of these relapsed 2 months after discontinuation of treatment. For the 7 dogs not cleared of mites, the dosage was doubled. Two of these were never cleared of mites. In phase 2, 12 of 13 dogs were cleared of mites after 60 to 180 days of treatment.
Clinical implications: High-dose milbemycin was effective in the treatment of generalized demodicosis.