First Companion Ivermax Paste (Ivermectin) 1.87% is an equine wormer designed to control bots, large strongyles, small bloodworms, roundworms, threadworms, pinworms, lungworms, and large mouth stomach worms. One syringe will treat a horse that weighs up to 1,250 lb. Ivermectin 1.87% is safe for pregnant mares, breeding stallions, and any age of foal.