− | Foals younger than 6 months in poor condition, on a poor worming schedule and with a heavy parasite burden.<ref name="Bliks">Blikslager, A.T (2010) ''Obstructive Disorders of the Gastrointestinal Tract'' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Chapter 15, ''Saunders''.</ref> Adult horses demonstrate age-related immunity which starts to develop from around 6 months and is substantial by about 15 months depending on worm exposure. | + | Foals younger than 6 months in poor condition, on a poor worming schedule and with a heavy parasite burden.<ref name="Bliks">Blikslager, A.T (2010) ''Obstructive Disorders of the Gastrointestinal Tract'' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Chapter 15, ''Saunders''.</ref> Adult horses demonstrate age-related immunity which starts to develop from around 6 months<ref>Clayton, H.M (1986) Ascarids. Recent Advances. ''Vet Clin North Am Equine Pract'', 2(2):313-328.</ref> and is substantial by about 15 months depending on worm exposure. |