Water Exposure

Water exposure studies have been conducted with Advocate^® to ascertain the effect that water immersion would have on the moxidectin component of the formulation. The residual properties and effectiveness of imidacloprid, due to its localizing in the water-resistant lipid layer of the skin, are well documented.¹

A pre-requisite of topically-applied products for heartworm prevention is the evaluation of the effect of water exposure, as well as shampooing, on efficacy. Studies were carried out to determine the efficacy of Advocate following bathing/shampooing, as well as simulated swimming/rain exposure.

In one of these studies², dogs were infected with 50 L3 D. immitis larvae on day 0 and treated with Advocate 34 days post-infection. The 40 dogs in this study were divided into 5 groups of 8 dogs each. Dogs in one group were exposed to water 1 hour post- treatment and those in another group on days 1, 7, 14, 21 and 28 post-treatment. To determine the effect of shampooing, dogs were either washed 4 hours post-treatment or 1 day post-treatment. One group of dogs was left untreated, but still exposed to water on a weekly basis.

All dogs were examined for the presence of adult heartworms at day 153 post-infection (day 119 post-treatment). No adult heartworms were recovered from any of the Advocate-treated dogs following water exposure or shampooing. In contrast, a mean of 21.7 D. immitis worms were recovered from the untreated control dogs.