To determine the efficacy of a 12.5 per cent spot-on formulation of pyriprole (Prac-Tic; Novartis Animal Health) and that of a combination of 10 per cent imidacloprid and 2.5 per cent moxidectin (Advocate; Bayer Animal Health) against Sarcoptes scabiei on dogs, 20 naturally infested adult dogs were ranked according to their pretreatment mite counts, allocated to one of two groups and housed individually in pens. Two spot-on treatments with each product, 30 days apart, were administered. Mite counts and clinical assessments were performed on each dog two days before treatment, and 28, 60 and 90 days after treatment. Efficacy was measured on the basis of the presence or absence of live mites. Except for day 60 following treatment, on which a single dog in the group treated with pyriprole was positive, no live mites were found on the treated dogs during the assessments on days 28, 60 and 90. Thus, efficacy measured on the basis of this finding (day 90 assessment) was 100 per cent. On final assessment, all dogs treated with pyriprole had 100 per cent resolution of papules, but crusts resembling healing lesions were still present on two dogs. Those treated with imidacloprid and moxidectin had 100 per cent resolution of papules and crusts. Hair regrowth, to greater than 90 per cent of pretreatment hair cover, was observed on all 20 dogs.