A comparison of two programs (pyrantel tartrate administered daily and 3X pyrantel pamoate adminitered at 8-week intervals) for the reduction of tapeworm EPG in the horse

A 26-week study was conducted with 24 horses to compare the effectiveness of two different treatment regimens in reducing the number of tapeworm eggs per gram (EPG) of feces. Ten horses were treated daily with 2.6 mg/kg of pyrantel tartrate (approved normal dosage for nematodes). Eleven horses received pyrantel pamoate at 8-week intervals at 19.8 mg/kg (3X the normal use for nematodes). Three horses served as controls and received ivermectin at 8-week intervals. Levels of tapeworm EPG were monitored at 2-week intervals for the duration of the 26-week period of study. Prior to administration of the first treatment, all 24 horses had positive EPG counts. Following the second week of treatment, no tapeworm eggs were detected in fecal samples of the 10 horses treated with pyrantel tartrate. Of the 11 horses treated with 3X pyrantel pamoate at 8-week intervals, one to two at each sample collection date had positive tapeworm EPG counts through the tenth week following the initial treatment, that is, through two weeks following the second 3X pyrantel pamoate treatment. Of the three control horses treated only with invermectin, at least one, and sometimes all three, had positive EPG counts at each collection date, indicating continuous tapeworm infection.