Evaluation of the efficacy of an imidacloprid 10% / moxidectin 2.5% spot-on against Sarcoptes scabiei var canis on dogs

The aim of this study was to determine whether two treatments with a novel formulation of Imidacloprid 10% plus Moxidectin 2.5%, administered four weeks apart, would be effective against Sarcoptes scabiei var canis on dogs. Thirty dogs naturally infested with S. scabiei were used in the study and allocated to two groups of 15 each. One group was treated with the Imidacloprid / Moxidectin Spot-on at 0.1ml / kg body weight and the second group with Selamectin at 0.05ml / kg (6mg / kg) body weight. Treatments were blinded and were administered as topical applications on Days 0 and +28. Efficacy was assessed by taking skin scrapings from five body regions suspected of being infested on each dog, and mite counts were done on these. Clinical symptoms and the extent of sarcoptic lesions were assessed on each dog and recorded. Assessments were made 8 days after the first treatment and subsequently at fortnightly intervals until Day +50 or +64. On Day +8 S. scabiei was found in skin scrapings of two dogs treated with the Imidacloprid / Moxidectin solution and of three dogs treated with Selamectin. From Day +22 and onwards no S. scabiei mites were detected in the skin scrapings of any of the dogs. Based on the absence of mites, as well as a complete resolution of papules and crusts and a marked reduction (>80%) in the surface area of skin exhibiting alopecia, 7.1%, 92.9% and 100% of the dogs treated with the Imidacloprid / Moxidectin solution were categorized as an overall success in terms of treatment on Days +22, +50 and +64 respectively.