Large Redworm (Strongylus vulgaris and Strongulus edentatus)

The large redworm differs from small redworms in size and life cycle.

Horses become infected by ingesting larvae as they are grazing.

The larvae of large redworms are an important cause of disease.  They migrate through the blood vessels to the arteries of the intestinal tract where they can cause severe damage.


After about six months they return to the intestine as egg-laying adult worms. Adult worms vary in size between 1.5 and 5 cm and, in large numbers, can cause a number of different disease problems.