|How embarrassing - my posterior bulb is showing!|
Named because the female pinworm has a distinctive long, pin-like tail, this parasite resides primarily in the colon of horses. The female adult worms the migrate to the rectum of the horse to lay their eggs. This creates a stick white-yellow paste around the perianal region of the infected horse. Understandably, this is itchy and pinworm-infected horses characteristically rub their tails on stall doors and fence posts, subsequently breaking tail hairs.
Rarely a pinworm-infected horse suffers from clinically significant health problems other than broken tail hair.