Cyathostome fecal egg count trends in horses treated with moxidectin, ivermectin or fenbendazole

Commercial preparations of fenbendazole (Safe-Guard (R), Intervet), ivermec tin (Eqvalan (R), Merial) or moxidectin (Quest (R), Fort Dodge) were admini stered once to horses scheduled for routine parasiticide treatment. In tota l, 93 horses from six cooperating farms were used in the study. Computer ge nerated. random allocation of horses to treatment group was conducted at ea ch farm. Fecal egg counts were determined for all horses on trial days 0, 5 6, 84 and 112, with corresponding calendar dates that were unique to each f arm, Only strongyle egg counts from animals which were positive at day 0 we re used for analysis of variance and comparisons. Counts for the three trea tment groups were similar at day 0, moxidectin < ivermectin < fenbendazole for days 56 and 84, and moxidectin < ivermectin = fenbendazole on day 112 ( P < 0.05). Reductions of geometric mean egg counts from day 0 levels were 9 9.1, 97.6 and 94.9% for moxidectin, 16.4, -27.0 and -32.0% for fenbendazole and 85.9, 124.2 and -8.1% for ivermectin on trial days 56, 84 and 112, res pectively. Adverse reactions to treatment were not observed for any of the parasiticides. (C) 2001 Elsevier Science B.V. All rights reserved.