A modified critical test for the efficacy of pyrantel pamoate for Anoplocephala perfoliata in equids.
Aims of this study with 13 equids naturally infected with Anoplocephala perfoliata were to document (i) a critical test with a period of 48 h from treatment to necropsy to assess the efficacy of an anthelmintic against the tapeworm, (ii) the efficacy of pyrantel pamoate oral paste at 13.2 mg pyrantel base/kg body weight, and (iii) the time after treatment when fecal egg counts would best estimate the tapeworm's prevalence in a herd. Feces passed in successive 12-h periods after treatment were examined for tapeworms. At necropsy, tapeworms in equids were identified as attached to the mucosa or unattached and, with a stereoscope, as normal or abnormal. At the time of treatment and at 6-h intervals thereafter, fecal samples were taken for egg counts. The efficacy of pyrantel pamoate was 96.6%; in 1 equid the efficacy was 75.3%, and in 8 it was 100%. "Major fragments" (worms without a scolex) accounted for 10% of the tapeworms recovered; they were not included in the efficacy analysis but should be. In 3 untreated equids necropsied, tapeworms were in the cecum, and 21.3% were detached. This protocol, when compared with a 24-h one without examination of feces, was more efficient in the treatment of trial animals and reduced underestimation and overestimation of an anthelmintic's efficacy. However, a protocol similar to this 48-h critical test but with a 24- or 36-h post-treatment period should be investigated. The mean egg count peaked 18 to 24 h after treatment and the samples taken at that time would provide the best estimate of prevelance of tapeworms in a herd. The Cornell-Wisconsin centrifugal flotation technique had a sensitivity and specificity of 100% at 18 h and 92% and 100%, respectively, at 24 h.
Slocombe
J Owen D
JO
Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario. oslocombe@uoguelph.ca
D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002589:Cestoda / Q000187:drug effects* / Q000254:growth & development; D002590:Cestode Infections / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D005243:Feces / Q000469:parasitology; D005260:Female; D006734:Horse Diseases / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology; D006736:Horses; D008297:Male; D010270:Parasite Egg Count / Q000662:veterinary; D015995:Prevalence; D011716:Pyrantel Pamoate / Q000494:pharmacology* / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013997:Time Factors; D016896:Treatment Outcome
D000969:Antinematodal Agents; D011716:Pyrantel Pamoate