This parasite has an intermediate host called the muscid fly.

Size/Appearance: The worms are small, long and slender and 1-2.5cm long.

Location in Horse: The stomach worm lives in the stomach causing irritation and damage to the stomach lining. Larvae can be deposited by the fly in skin wounds or around the eye. These larvae do not continue their development, but prevent wounds from healing, known as ‘summer sores’.

Symptoms: Symptoms include mild gastritis and also ‘summer sores’.