modified critical test for the efficacy of pyrantel pamoate for Anoplocephala perfoliata in equids

• Published in: Canadian journal of veterinary research 2004-04, Vol.68 (2), p.112-117
• Main Author: Slocombe, J.O.D
• Format: Article
• Language: English
• Subjects: accuracy; Animals; Antinematodal Agents - pharmacology; Antinematodal Agents - therapeutic use; Cestoda - drug effects; Cestoda - growth & development; cestode infections; Cestode Infections - drug therapy; Cestode Infections - epidemiology; Cestode Infections - parasitology; Cestode Infections - veterinary; diagnostic techniques; fecal egg count; Feces - parasitology; Female; Horse Diseases - drug therapy; Horse Diseases - epidemiology; Horse Diseases - parasitology; Horses; Male; Parasite Egg Count - veterinary; Prevalence; Pyrantel Pamoate - pharmacology; Pyrantel Pamoate - therapeutic use; Sensitivity and Specificity; Time Factors; Treatment Outcome
• ISSN: 0830-9000

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.