EFFICACY OF MOXIDECTIN 2-PERCENT EQUINE GEL AND EQVALAN 1-PERCENT PASTE AGAINST NATURALLY ACQUIRED INTERNAL PARASITE INFECTIONS IN HORSES

A field test was completed on 32 horses naturally infected with the ne matodes Parascaris equorum, Strongyloides westeri and small strongyles . The efficacy of a new moxidectin gel formulation (Moxidectin 2% Equi ne Gel, Cyanamid) was compared with the ivermectin horse paste (Eqvala n 1%, MSD AGVET). Drug activity in the treated group was monitored by egg counts on days 1, 7, 14, 28, 56, 70 and 84 days post treatment. Fa ecal cultures indicated that only small strongyles (Cyathostominae) we re present. Horses treated with a single 0.4 mg.kg(-1) b.w. dose of mo xidectin had negative strongy-le egg counts at intervals between 14-70 th day post treatment. In the group of horses treated with a single 0. 2 mg.kg(-1) b.w. dose of ivermectin, negative strongyle egg counts wer e observed at intervals 14 and 28 days post treatment, while on the 56 th day the reappearance of small strongyles eggs in faeces was confirm ed. Moxidectin showed a significantly longer persistent effect than iv ermectin. The efficacy of moxidectin against P. equorum and S. westeri was 100% from Day 14 until the end of the trial. Both drugs were well tolerated.