Pin worms (Oxyuris equi)
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Pinworms are the worms responsible for the statement often heard (my horse must have worms because it is rubbing it’s tail). The glue the adult female worm attaches her eggs to the exterior rectal tissue with is very irritating to the tissue. This irritation in the past has been a major cause of tail rubbing. However, due to the improvement in deworming medications and the cleanliness in most stables today the problems due to pinworms has been greatly reduced.