Clearance of Pentatrichomonas hominis following ronidazole treatment in a dog with chronic diarrhoea persisting despite metronidazole administration

Abstract

Pentatrichomonas hominis is generally regarded as a commensal organism in dogs; however, its clinical significance in diarrhoea and optimal treatment strategies remain unclear. A 6‐month‐old female Shiba dog presented with persistent diarrhoea. Despite prolonged treatment with metronidazole, febantel and fenbendazole for giardiasis, as well as prednisolone for suspected chronic inflammatory enteropathy, the clinical signs did not resolve. Faecal PCR testing, including testing for trichomonads, detected P. hominis . Treatment with ronidazole resulted in marked improvement in faecal consistency and clearance of P. hominis on follow‐up PCR testing, without any adverse reactions. The dog was later diagnosed with food‐responsive enteropathy. This case suggests that P. hominis may have been associated with diarrhoea in dogs with underlying disease or immunosuppression. In addition, ronidazole may be a therapeutic option when the organism persists despite metronidazole treatment. P. hominis infection should be considered in dogs with persistent diarrhoea, particularly when conventional treatments fail.