Horses can be hosts to various types of parasites, including strongyles, roundworms, tapeworms, and pinworms. These parasites can lead to colic, weight loss, anemia, and in severe cases, death. Regular deworming is vital not just for individual horses but also for the herd's overall health since some parasites can spread quickly among horses that share a pasture or barn. Additionally, untreated infestations can lead to the development of resistant worm strains, making it increasingly difficult to treat future infections.