ClinQuiz: Equine parasites, answer 5B
5) B — Correct.
These are eggs of Oxyuris equi, the pinworm of horses. Adult female O. equi migrate to the anus and deposit eggs within an adhesive fluid onto the perianal folds. The eggs stick to a horse's perianal region and create pruritus, causing the horse to rub against stationary objects in the environment to try to relieve the discomfort. The eggs are then transferred to fomites such as posts or stall doors and are available to infect other horses that ingest the eggs.18 Although more readily recovered by direct examination methods such as a clear acetate tape preparation, O. equi eggs can also be found on fecal flotation.