This study was undertaken to determine
selamectin residue in dog's blood and in gloves worn while petting dogs after Revolution application. Revolution contains the active ingredient
selamectin (a semisynthetic
avermectin), which controls endoparasites and ectoparasites, including adult fleas, flea eggs, ticks, heartworms, ear mites, and
sarcoptic mange in dogs, for 30 days. Revolution was applied topically on a group of six adult house hold dogs (240 mg
selamectin/dog). The gloves worn for 5 min while petting the dogs were collected in glass jars and the blood samples (5 mL/dog) were collected in
EDTA tubes at 0 h, 24 h, and 72 h, and at 1, 2, 3, 4, and 5 weeks post-Revolution application for
selamectin residue determination. At no time during the study did the dogs show any signs of toxicity,
weight loss, or change in body temperature. Extracts of the blood and the gloves were analyzed for
selamectin residue using RP-HPLC coupled with a UV detector (246 nm).
Selamectin standard used for peak identification and quantitation was purified from Revolution.
Selamectin residue was detected in the blood (10.26 +/- 1.06 ng/mL) only at 72 h post-Revolution application, probably due to its poor dermal absorption and rapid elimination from the circulation. In the glove extracts, the highest concentration of
selamectin (518.90 +/- 66.80 ppm) was detected 24 h after Revolution application. Transferable residue of
selamectin in gloves from dog's coat was detected at a lesser magnitude after 1 week of Revolution application, and that was followed by a further descending trend during the second, third, and fourth weeks. No
selamectin residue was detected in the glove extracts after the fifth week. In spite of
selamectin's binding to the sebaceous glands of the skin, gloves contained significant transferable residue. Thus, these findings suggest that repeated exposure to
selamectin can pose potential health risks, especially to veterinarians, veterinary technologists, dog trainers/handlers, and pet owners.