The efficacy of injectable and pour-on formulations of moxidectin against lice on cattle.

The efficacy of one administration of moxidectin against natural infestations of the 3 common species of cattle lice in Australia: Linognathus vituli, Damalinia bovis and Haematopinus eurysternus, was determined. A high degree of control of L vituli (the long-nosed sucking louse) was achieved with both the cattle injection (96.7% and 100%) at 0.2 mg/kg and the cattle pour-on formulation (94.6% and 100%) at 0.5 mg/kg on the 2 farms where this louse occurred. An injection of moxidectin at 0.2 mg/kg did not eliminate D bovis. In these trials efficacy ranged from nil to 85.2%. In contrast the pour-on formulation at 0.5 mg/kg provided consistently high efficacy (83.6 to 100%) against D bovis on 3 farms. Infestations of H eurysternus (the short-nosed sucking louse) were low and no significant difference was recorded between treatment groups in a single trial, however, lice persisted on 3 to 7 cattle in the untreated group at each inspection, whereas none were found on any animals in the 2 groups treated with moxidectin on inspection after treatment.