Variable activity of Disophenol against hookworms and lice of northern fur seal pups on St. Paul Island, Alaska

Six critical tests with disophenol were conducted in July, 1978, in fur seal pups (Callorhinus ursinus) naturally-infected with adult hookworms, Uncinaria lucasi, and infested with various stages of two species of sucking lice, Proechinopthirus fluctus (Ferris) and Antarctophthirus callorhini (Osborn). Disophenol at a dose rate of 12.5 mg/kg was administered subcutaneously to each of six pups. Each pup was contained in an individual cage for 60 h post-treatment at which time pups were exmained at necropsy. Efficacy against hookworms ranged from 2% to 88% and of both species of lice ranged from 26% to 90% for the six pups. Disophenol removed approximately 90% of all adult lice but only slightly more than 60% of all nymphs. The only sign of toxicosis was a probable drug related fluid-like feces for four pups from 12 to 60 h posttreatment.