THE EFFICACY OF INJECTABLE AND POUR-ON FORMULATIONS OF MOXIDECTIN AGAINST LICE ON CATTLE

The efficacy of one administration of moxidectin against natural infes tations of the 3 common species of cattle lice in Australia: Linognath us vituli, Damalinia bovis and Haematopinus eurysternus, was determine d. A high degree of control of L vituli (the long-nosed suckling louse ) was achieved with both the cattle injection (96.7% and 1 00%) at 0.2 mg/kg and the cattle pour-on formulation (94.6% and 100%) at 0.5 mg/k g 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 rang ed from nil to 85.2%. In contrast the pour-on formulation at 0.5 mg/kg provided consistently high efficacy (83.6 to 1 00%) against D bovis o n 3 farms. Infestations of H eurysternus (the short-nosed sucking lous e) were low and no significant difference was recorded treatment group s in a single trial, however, lice persisted on 3 to 7 cattle in the u ntreated group at each inspection, whereas none were found on any anim als in the 2 groups treated with moxidectin after treatment.