Itchy ticks and tick lesions cause pastured horses to ferociously rub trees, fences and shelter walls, abrading throats, necks and hindquarters and destroying their manes and tails. Severe infestations produce anemia, loss of appetite and depression. Ticks can infect any horse—or horse owner—with Lyme disease, ehrlichiosis, Rocky Mountain spotted fever and tick-bite paralysis. Standard insect solutions rarely phase these rugged pests.