Comparison of ivermectin, oxibendazole, and pyrantel pamoate in suppressing fecal egg output in horses.

The research study compares the efficacy of three deworming medicines, ivermectin, oxibendazole, and pyrantel pamoate, in reducing fecal egg output in horses. Results indicate that ivermectin is the most effective of the three, leading to a significantly longer period before the return of eggs in feces.

Research Setting & Methodology

• The study was conducted in a boarding stable in Alberta, involving 30 resident horses.
• The goal of the research was to evaluate which of the three dewormers (ivermectin, oxibendazole, or pyrantel pamoate) was most effective in suppressing fecal egg output in horses.
• The horses were blocked based on pre-treatment egg counts and evenly divided into three groups, each of which was treated with one of the three de-wormers. The dewormers were administered orally as a paste.
• Fecal samples were collected preceding the treatment and then every 4-11 days over 72 days for examination.

Results

• For the first 35 days after administration of the dewormers, the researchers observed few if any strongyle eggs in the feces of all horses.
• On days 42, 50 and 57, the ivermectin group showed significantly lower egg counts than the groups treated with oxibendazole or pyrantel pamoate.
• Survival curve analysis revealed that the recurrence of eggs in feces took significantly longer in the ivermectin group than in the other two groups.

Conclusions

• The study concluded that, under the conditions encountered in this study, ivermectin appears to be more effective than oxibendazole or pyrantel pamoate in suppressing eventual fecal egg out-put in horses.
• The interval to recurrence of fecal egg output in horses treated with ivermectin was eight to nine weeks, compared with five to six weeks for horses treated with either oxibendazole or pyrantel pamoate.