Pinworms (Oxyuris sp.) cause which clinical signs in horses?

• A. Pruritus, Excoriations, Broken Hair at Tail Base
• B. Coughing
• C. Diarrhea
• D. Lameness

Answer: (A)

Pinworms cause perianal itching in horses. The female worm migrates to the perianal region to lay eggs, which irritates the skin and triggers intense pruritus. To relieve the itch, the horse rubs its hindquarters on fences or stalls, leading to excoriations and broken hair at the base of the tail. This tail-base dermatitis with hair breakage is a classic sign of Oxyuris equi infection. Signs like coughing, diarrhea, or lameness aren’t typical for pinworms and point to other issues instead.