ATYPICAL EXTERNAL CHARACTERISTICS OF ANOPLOCEPHALA-PERFOLIATA IN EQUIDS IN CENTRAL KENTUCKY

As part of a study evaluating efficacy of pyrantel tartrate fed at the low dose rate (2.64 mg/kg) once daily for 30 consecutive days against Anoplocephala perfoliata in Thoroughbreds on Farm A in central Kentuc ky, about two-thirds of the feces passed by yearlings (n = 58) for 2 d ays postinitial treatment day was examined for specimens of this paras ite. Efficacy data are given elsewhere (Lyons, et al., 1997), and obse rvations on external characteristics of A. perfoliata specimens recove red from feces are presented here. Of a total of 401 A. perfoliata spe cimens with scolices found in feces of 43 of the yearlings, external f eatures were typical (normal strobila and scolex with 4 suckers/4 lapp ets) for 97.5% (n = 391 specimens). However, 2.5% (n = 10) were atypic al: (a) 1 had a normal strobila but a scolex with 6 suckers/4 lappets, (b) 7 had a triradiate strobila and a scolex with either 5 suckers/6 lappets (n = 1) or 6 suckers/6 lappets (n = 6), and (c) 2 had a tetrar adiate strobila and a scolex with either 7 suckers/7 lappets or 8 suck ers/8 lappets. Reexamination of 22,557 specimens of A. perfoliata from equids in previous investigations at the University of Kentucky, for comparison of external characteristics in specimens from Farm A horses , revealed 99.95% (n = 22,545) were typical and 0.05% (n = 12) were at ypical (all had a triradiate strobila and a scolex with 6 suckers/6 la ppets).