RESUMO
The prevalence of infection with cyathosthomes of horses is high worldwide. Identification of species on infective larvae based on available morphological keys is not fully accurate and the aim of the present study was to provide a reliable identification key of cyathostomes infective larvae. At the abattoir, horse large intestines were examined and the cyathostomes females extracted and identified. The eggs from uteruses of identified cyathostomes females were used for breeding the infective larvae. Morphological parameters of Cyathostominae infective larvae, i.e. the length of the larvae with sheath, length of oesophagus, intestine, end of the intestine to the end of the larvae body, and finally the body breadth measured and the cells arrangement of the intestine cells (A-D) noted. These morphological parameters of the third infective larvae were determined of the following cyathostomes species: Cylicocyclus nassatus, Cylicostephanus goldi, Cyathostomum catinatum, Cylicostephanus longibursatus, Cyathostomum pateratum, Cylicocyclus ashworti, Cylicocyclus insigne, Cylicostephanus calicatus and Coronocyclus coronatus. The qualitative assignment into A, C and D intestinal type and then the combination of morphological measures allows specific identification for most species.