Efficacy of a pour-on formulation of doramectin against lice, mites, and grubs of cattle

Objective-To determine effectiveness of a pour-on formulation of doramectin against Damalinia bovis, Haematopinus eurysternus, Linognathus vituli, Sol enopotes capillatus, Chorioptes bovis, Sarcoptes scabiei, Hypoderma bovis, and Hypoderma lineatum. Animals-Cattle of various ages with naturally acquired or artificial infest ations with 1 or more species of lice, mites, or grubs. Procedure-In 10 louse and 6 mite studies, cattle were treated with doramect in (500 mu g/kg, topically) on day 0, and parasite counts were performed ap proximately weekly from days 0 to 35. In 6 grub studies, cattle expected to harbor Hypoderma spp were treated before emergence of warbles. After warbl es began to emerge, they were counted every 2 weeks, and grubs were collect ed and identified by species. Results-Burdens of D bovis, H eurysternus, L vituli, and S capillatus on do ramectin-treated cattle were 0 by 28 days after treatment. Burdens of C bov is and S scabiei decreased to 0 in naturally infested cattle and approximat ely 0 in artificially infested cattle by day 14 to 15. In grub studies, 107 of 136 control cattle had warbles, whereas 2 of 136 doramectin-treated cat tle had 1 warble each, which represented a cure rate of 98.5%. Conclusion and Clinical Relevance-One topical application of doramectin was highly efficacious against common species of lice, miles, and grubs known to affect performance, health, and appearance of cattle.