COMPARISON OF COST AND EFFICACY BETWEEN 2 PARASITE CONTROL PROGRAMS USED IN YOUNG HORSES

Seventeen young horses were used in a crossover study to compare two d eworming programs: a daily program using pyrantel tartrate and a tradi tional eight-week rotation program, using ivermectin and fenbendazole. In both weanling and yearling horses, the daily program maintained lo wer mean strongyle egg per gram (EPG) counts than the rotation program (p = 0.0001, both treatment periods). However, there were significant (p = 0.0001, both treatment periods) interactions between treatment p rogram and post-treatment time interval. Both programs were very effec tive in the early weeks of both treatment periods, but the rotation pr ogram was less effective in the later weeks. In the weanling horses, t he daily program was significantly (p = 0.0470) more effective than th e rotation program at minimizing the egg output of Parascaris equorum. Few ascarid eggs were recovered from the yearling horses in both grou ps. There were no differences in cumulative bodyweight gain between tr eatment programs in both weanling and yearling horses. The average mon thly cost of the daily program ($17.78) was significantly (p < 0.0001) higher than the average monthly cost of the rotation program ($3.33). Fenbendazole is the probable cause of the reduced efficacy in the rot ation program. The presence of small strongyles resistant to fenbendaz ole has been reported in North Central Florida. Using alternative prod ucts that remain effective against small strongyles, a carefully desig ned rotation program may be as effective and less expensive than a dai ly pyrantel tartrate program. The situation in which treatment with da ily pyrantel tartrate may be most advantageous is in a multi-owner of boarding facility where animals graze pastures shared by horses on var ious parasite control programs.