After this time, infection rates begin to decline and is extremely uncommon in horses over twelve months of age.

[5] Eggs have a thick, multilayered shell for protection and the ability to adhere to any surface they touch once expelled.

In a three-month life cycle, the swallowed eggs become larva and migrate from the small intestines into blood vessels and from there travel to the liver, where they molt into another larval stage.

[5] At this point, they are coughed up and re-swallowed, where the larvae mature into adult roundworms that produce eggs.

Feed absorption is often reduced, and other clinical signs may include unthriftiness, potbelly, rough hair coat, and slow growth.

[3] However, when an infection is found in an adult horse, both the worm and egg counts are substantially low.

[6] Effective treatments include the macrocyclic lactones, notably ivermectin or moxidectin, which can kill the early larval stages before they migrate into the liver and lungs.

[3] Keeping pastures and stables free of manure has been shown to be effective in reducing parasite infestations in horses.