CONTROLLED DOSE CONFIRMATION STUDY OF A 2-PERCENT MOXIDECTIN EQUINE GEL AGAINST EQUINE INTERNAL PARASITES IN THE NETHERLANDS

The efficacy of a 2% moxidectin equine gel at a dosage rate of 0.4 mg kg-l was evaluated in a controlled trial at Utrecht University. Twelve yearling castrated male Shetland ponies grazed a pasture of 2 ha from May 1994 until housing in November. Six ponies were treated with moxi dectin, whereas the others served as non-treated controls, Necropsy wa s carried out 35 days after treatment. Greater than 99% efficacy of mo xidectin was observed on faecal egg output. No effect of moxidectin wa s observed on mucosal inhibited early cyathostome L3 (EL3) or on the t otal numbers of mucosal developing stages. However, a 89.6% reduction was observed on large mucosal fourth stage larvae (L4). Moxidectin tre atment probably triggered resumption of development of EL3. Moxidectin appeared to be highly effective (95-100%) on lumenal LA cyathostomes, adult strongylids, Strongylus vulgaris larvae from the arteries, S. e dentatus larvae from the abdominal wall and Trichostrongylus axel. Mox idectin had relatively poor efficacy against Gasterophilus intestinali s and had no effect on Anoplocephala perfoliata. No side-effects of mo xidectin treatment were observed.