Although pinworm are not thought to be harmful to your horse, they can be irritating because the adult female lays her eggs around the anus of the horse causing itching of the tail and surrounding area, which in turn can lead to fly strike.

Size/Appearance: Pinworms can be up to 10cm and are white in colour.

Location in Horse: The pinworm lives in the colon, but migrates to the rectum to lay its eggs.

Symptoms: Symptoms include an itchy anus and fly strike. Often mistaken for sweet itch.