Pinworm (Oxyuris equi) Infection in a Horse: Diagnosis and Treatment Outcomes

Background: Equine pinworm infection may cause marked perianal irritation and tail rubbing, making clinical recognition and parasitological confirmation important. Aims: To describe the clinical presentation, parasitological diagnosis and therapeutic management of equine oxyurosis caused by Oxyuris equi in a Marwari cross mare. Presentation of Case: A three-year-old Marwari cross mare weighing 255 kg was presented to the Veterinary Clinical Complex, Veterinary College and Research Institute, Salem, with a history of perianal itching, tail rubbing, dullness and localised hair loss with scab formation. The mare had no previous history of deworming. Clinical examination revealed perianal irritation, alopecia and scab formation. Parasitological examination using the perianal adhesive tape impression technique and faecal examination revealed eggs morphologically consistent with O. equi. The mare was treated with doramectin (0.2 mg/kg body weight; 5.1 ml) intramuscularly and piperazine hydrate (226 mg/kg body weight; 94 ml) through a nasogastric tube. Cetrimide cream was applied topically to the affected perianal region twice daily, along with appropriate hygienic measures. Marked reduction in tail rubbing and perianal irritation was observed following treatment. At the three-week follow-up, the mare showed clinical recovery, and two consecutive perianal adhesive tape impressions and faecal examinations yielded negative results. Discussion: Equine oxyurosis is characterised by perianal pruritus, tail rubbing and localised alopecia resulting from egg deposition by gravid female worms around the perianal region. This case highlights the diagnostic value of the perianal adhesive tape impression technique, particularly when supported by faecal examination, in identifying O. equi infection. Conclusion: Early recognition of characteristic clinical signs, appropriate parasitological diagnosis, anthelmintic treatment and hygienic management are important for successful clinical recovery and minimising the risk of reinfection in horses.