Three recently recognized species of cyathostomes (Nematoda: Strongylidae) in equids in Kentucky

Abstract

Three species of cyathostomes--Cylicocyclus ashworthi, Cylicostephanus bidentatus, and Cylicostephanus hybridus were identified recently in horses in Kentucky. General characteristics and distinguishing description of these species are presented. Distribution of these species and their role in the horse strongylid community are discussed. The importance of examining the entire contents of the large intestine or alternatively a high number of specimens in order to recover and identify species residing in low numbers is stressed.

Meta-analysis of cyathostomin species-specific prevalence and relative abundance in domestic horses from 1975–2020: emphasis on geographical region and specimen collection method

“…Incorporation of fecal examination within critical tests for estimating anthelmintic efficacy results in a conservative underestimation of initial efficacy [20]. However, using critical test data as estimates of species-specific prevalence and relative abundance within sampled component communities potentially lead to an inappropriate bias toward more abundant species, and uncommon species were more likely to be missed during recovery from feces [7,20,25]. Species infrapopulation totals were diluted further when only identifying a small percentage or predetermined number of the total specimens recovered [7] and again when adding these to the total number of specimens recovered at necropsy within critical tests to infrapopulation totals per horse.…”

“…hybridus were not recognized as cyathostomins infecting NAm horses [24]. This was amended in a later publication [25], which also acknowledged the misidentification of Cys. bidentatus as Cys.…”

“…Articles were required to cite cyathostomin adult morphologic identification keys with currently accepted species taxonomic designations and species assignment criteria (i.e. [ 1 , 23 – 25 ]). The Lichtenfels et al keys [ 1 , 23 ] were generated and accepted by consensus of the equine helminthology research community following several World Association for the Advancement of Veterinary Parasitology (WAAVP) workshops and validated by the International Commission on Zoological Nomenclature (ICZN) [ 1 ].…”

“…The Lichtenfels et al keys [1,23] were generated and accepted by consensus of the equine helminthology research community following several World Association for the Advancement of Veterinary Parasitology (WAAVP) workshops and validated by the International Commission on Zoological Nomenclature (ICZN) [1]. The Tolliver key [24], amended by Kuzmina et al [25], agrees with the Lichtenfels et al keys, using a practical approach to reach the same identifications. Other keys yield outdated and incorrect species assignments, and studies using these were excluded.…”

Fatal parasite-induced enteritis and typhlocolitis in horses in Southern Brazil

“…The presence of larvae on gross and histopathological examinations is essential to obtain a final diagnosis of cyathostomiasis, since fecal egg counts are often zero or very low during larval cyathostomiasis, with the passage of many L4 with the feces (LOVE et al, 1999;LYONS et al, 2000;REINEMEYER, 1986). However, identification at the species level was not possible in the present study, since foals less than 1 year old mostly present juvenile nematodes (KUZMINA et al, 2011), with no adult parasites present, as in the present study. This probably occurred due to the fact that cyathostomiasis is related to the emergence of immature parasites that do not reproduce yet (REINEMEYER, 1986), and species identification relies mainly on adult parasites rather than larval stages (CORNING, 2009), because the larval stages possess fewer morphological characters than do adult worms (KHARCHENKO et al, 2009).…”