Lice are seen on the head, neck, mane and tail during winter and early spring. Lice produce several generations per year and can complete a life cycle in three weeks. The horse biting louse, Bovicola equi , also infests horses. They feed on the epidermal skin tissues and secretions. Poultry lice have occasionally infested horses.
Infested horses rub, bite themselves, stomp and exhibit extreme annoyance and discomfort.
In the United States, horses serve as a primary host for two species of ticks and a secondary host for 14 other species. Heavy tick burdens can result in general unthriftiness, anemia and susceptibility to disease. Ticks carry diseases such as Lyme disease found in many Eastern states. This very small parasite is fairly uncommon to horses. Both feed on skin and tissue fluids.