Preliminary trials using a macrocyclic lactone against psoroptic scabies of cattle

A macrocyclic lactone, LL-F28249 alpha, C36H52O8, was evaluated as a one- or two-injection treatment in different formulations and concentrations against cattle infested with Psoroptes ovis (Hering). One injection of 2 mg kg-1 or two injections of 1 mg kg-1 of 3% active material in either an aqueous or oil formulation failed to eliminate all of the mites. A single injection of 3 mg kg-1 as a 5% aqueous formulation eliminated all mites for 35 days post-injection. At lower dosages of the aqueous formulation (3%), the male mites appeared to be less susceptible to the acaricide than either the female or immature mites.