The Life Cycle of Strongylus vulgaris in the Horse

Abstract

Summary In an attempt to elucidate the migratory route of Strongylus vulgaris larvae 9 worm-free pony foals were each infected with a pure culture of 750 infective larvae and killed at intervals over a period of 9 months. The results obtained show that infective larvae exsheath and penetrate the intestine within a few days of infection. These larvae then moult in the sub-mucosa, penetrate small arteries and have migrated within the lumina of intestinal arteries to the anterior mesenteric site by 14 days. In the predilection site larvae develop from early to late fourth stage and after a period of 3 to 4 months the fourth moult is completed and young adults return to the intestine again via the lumina of the arteries. Nodules are formed with the subsequent release of young adults into the intestinal lumen. The migration is complete by 6 to 7 months after infection.