Thousands of ranchers count on IVOMEC (ivermectin) Pour-On, season after season, to protect their cattle from worms, lice and horn flies. In the fall, IVOMEC Pour-On provides the longest lasting control of both biting and sucking lice, with a 100% Product Satisfaction Guarantee. Turn to IVOMEC Pour-On to protect your brood cows, raise thrifty heifers and wean heavier calves.