title: The prevalence and intensity of internal parasites of horses in the U.S.A.
abstract: Fifty-five adult horses were necropsied over a 15-month period, and their worm burdens counted and speciated. Twenty-one species of Cyathostominae were recovered. Ten species: Cyathostomum catinatum, Cylicocyclus nassatus, Cylicostephanus longibursatus, Cyathostomum coronatum, Cylicostephanus goldi, C. calicatus, C. minutus, Cylicocyclus leptostomus, C. insigne and Cyathostomum pateratum, comprised 98.9% of the total cyathostome burdens. These same 10 species also demonstrated high prevalences in 4 previous surveys. Eight of these 10 species have been shown to be resistant to benzimidazole anthelmintics. Anthelmintic resistance apparently had little effect on the prevalence of a species, but appeared to increase its relative abundance within a mixed population. The prevalence of other internal parasites was similar to previous reports, but Strongylus vulgaris adults and arterial lesions were less common.
mesh_terms: D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology; D004351:Drug Resistance; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology / Q000469:parasitology*; D006736:Horses; D008297:Male; D017205:Spirurida Infections / Q000453:epidemiology; D013319:Strongyle Infections, Equine / Q000188:drug therapy / Q000453:epidemiology; D014481:United States
chemical_list: D000969:Antinematodal Agents