EPRINOMECTIN - A NOVEL AVERMECTIN FOR CONTROL OF LICE IN ALL CLASSES OF CATTLE

Eight trials were conducted in the United States to determine the effi cacy of eprinomectin applied topically against four common species of lice in cattle. In two dose titration trials, eprinomectin dosages of 125 to 750 mcg/kg body weight applied topically were compared to untre ated controls. In dose confirmation studies, animals treated topically with eprinomectin applied at the rate of 500 mcg/kg were compared to vehicle-treated controls. Four species of lice were present in these t rials: Linognathus vituli, Haematopinus eurysternus, Solenopotes capil latus, all sucking Lice, and Damalinia (Bovicola) bovis, the cattle bi ting louse. Louse counts were made on six to nine predilection sites ( the same number of sites in all animals in the same trial) prior to tr eatment. The same sites were counted again seven days after treatment and weekly thereafter until trial termination eight weeks after treatm ent. When no lice were found in the predilection sites, a modified who le body search wa!; conducted. Each species of lice was present on at least six animals in each treatment group on at least one counting dat e in two or more trials. No lice were found on any animal treated topi cally with eprinomectin at a dosage of greater than or equal to 500 mc g/kg after 14 days posttreatment until termination of the trials eight weeks after treatment. (C) 1997 Elsevier Science B.V.