DOSE TITRATION OF MOXIDECTIN ORAL GEL AGAINST GASTROINTESTINAL PARASITES OF PONIES

Moxidectin was tested as an oral gel formulation during a controlled t est performed to evaluate dosages against equine gastrointestinal para sites, Four groups of ten ponies were used, Ponies ranged from 1 to 20 years of age and were naturally infected in southern Louisiana or Mis sissippi, Fecal. exams and fecal cultures were performed on all ponies to determine the strongyle egg counts and the percent distributions o f large and small strongyles, Following these determinations, ponies w ere allocated to replicates of four ponies to provide an even distribu tion of strongyle infection, age, weight and gender, Members of each r eplicate were then randomly assigned to one of four treatment groups, The doses tested were 300, 400 and 500 mu g kg(-1) body weight. The or al gel vehicle alone served as control. Treatments were administered b ehind the tongue and the ponies were observed continuously for 4 h for any adverse reactions; thereafter, ponies were observed at least twic e daily, Necropsy examinations were performed 14 days post-treatment f or the recovery and identification of any parasites present. Moxidecti n, at all doses tested, was 100% efficacious against adults of Strongy lus vulgaris, Strongylus edentatus, Triodontophorus spp. and 22 specie s of small strongyles, Moxidectin was also 100% efficacious against la rvae of Strongylus edentatus and Oxyuris equi, greater than 94% effica cious against Strongylus vulgaris larvae and Oxyuris equi adults at 14 days post-treatment. Moxidectin proved highly efficacious against lum inal small. strongyle larvae ( > 99.9% against L(4) and > 92% against L(3)) and moxidectin demonstrated some efficacy against encysted small strongyle larvae as well. Although control ponies were not uniformly infected with Habronema muscae, Trichostrongylus M-ei and Parascaris e quorum, none of these parasites were recovered from moxidectin-treated ponies, suggesting high efficacy against these species as well. Effic acy against Gasterophilus spp, was 89%, 96% and 97% in a dose-dependen t fashion. Moxidectin had no demonstrable activity against Anoplocepha la perfoliata.