A pilot trial evaluating the efficacy of a 10% imidacloprid/2.5% moxidectin spot-on formulation in the treatment of natural nasal capillariosis in dogs

The efficacy and safety of a spot-on formulation containing 10% imidacloprid and 2.5% moxidectin (Advocate®, Bayer Animal Health GmbH, Leverkusen, Germany) were evaluated in a pilot trial for the treatment of canine nasal capillariosis caused by Capillaria boehmi (syn. Eucoleus boehmi). Sixteen dogs copromicroscopically positive for C. boehmi eggs were confirmed, either by rhinoscopy or species-specific PCR-coupled sequencing assays, as being affected by nasal capillariosis. The animals were randomly allocated to two different study groups, i.e. one (Group T) treated with Advocate® and one (Group C) left untreated, in a ratio of 1:1. The animals underwent clinical examination and quantitative copromicroscopy for C. boehmi eggs on Days -6 and -2 (baseline) and Day 28 ± 2 (post-baseline). Animals in Group T received Advocate® on Day 0. On Day 28 ± 2 the efficacy of the treatment (Group T) or the persistence of the infection (Group C) was confirmed by rhinoscopy or, alternatively, by molecular procedures. Seven of the eight dogs in Group T were negative on Day 28 ± 2 (reduction of baseline faecal egg counts by 99.14%), while for one dog a second treatment on Day 28 ± 2 was necessary to clear the infection, as demonstrated on Day 56 ± 2 (reduction of baseline faecal egg counts by 100% in Group T). Seven animals in Group C received a rescue dose of Advocate® on Day 28 ± 2 and scored microscopically and molecularly negative for the parasite on Day 56 ± 2, thus increasing the reduction of post-baseline egg counts to 99.57% after a single administration. These promising results show that Advocate® spot-on is an effective formulation for the treatment of canine nasal capillariosis under field conditions.