Acute larval cyathostominosis in thoroughbred horses highlighting innovative diagnostic techniques

Abstract This study describes the clinicopathological findings, treatment outcomes and parasite community in nine horses presenting with acute larval cyathostominosis. Clinical signs, clinicopathological and parasitological parameters were recorded at presentation and recurrence of disease. Sanger sequencing was performed on PCR products obtained from larvae recovered from faeces. The most common clinical signs included weight loss, diarrhoea and pyrexia, with accompanying parameters consistent with marked systemic inflammation. Larvae were retrieved from six horses, and 116 were identified to species similarity level. Five common cyathostomin species were detected: Cylicocyclus nassatus , Cylicocyclus ashworthi , Coronocyclus coronatus , Cylicostephanus calicatus and Cylicostephanus longibursatus . One horse in the herd was euthanased, with postmortem results also reported here. Cyathostomin‐related disease can occur in any cohort of horses and can be successfully treated if recognised early; faecal larval detection could offer a valuable antemortem diagnostic, and Internal Transcribed Spacer 2 (ITS‐2) sequencing proved useful for identifying the species of larvae recovered.