Strongylosis in horses slaughtered in Italy for meat production: epidemiology, influence of the horse origin and evidence of parasite self-regulation

The influence of host and parasite-related factors on the strongyle infection in 50 horses coming from 6 European countries and slaughtered in Italy for meat production was investigated using a multivariable modelling approach. The study was carried out by examining adult helminths, faecal eggs (identified by culture to the third larval stage) and mucosal larval stages of Cyathostominae. A modified Transmural Illumination technique (TMI) has been performed and Cyathostominae empty mucosal cysts were also evaluated in order to obtain further indications about small strongyles dynamic. All species found in this study were previously reported in European horses. Major differences were detected comparing Hungarian (#24) and Italian (#13) horses. Sex was confirmed as uninfluential, while relations with host age were only partially consistent with the development of acquired resistance. The analysis of both mucosal Cyathostominae larvae (more in Italy) and of the percentage of empty cysts (higher in Hungary) along with lower large strongyle abundance in Hungary allowed to hypothesise a wider use of anthelmintic treatments in Hungarian horses compared to Italian ones. The results regarding adult Cyathostominae (no significant differences nor regarding age or origin) suggested the important role of ecological interactions between larval and adult stages in regulating small strongyle populations.