All horses get internal parasites, especially when they are kept where other horses have been. If you board, breed, travel or just hang out with other horsemen and their horses, you need to deworm your horse regularly. Damage caused by parasites can lead to serious gut problems including impactions, diarrhea and colic. Ivermectin is the most popular compound for equine deworming today. It has a broad range of activity against equine parasites. Horse Health (ivermectin paste) 1.87% provides effective treatment and control of the following parasites in horses: large and small strongyles, pinworms, ascarids, hairworms, large-mouth stomach worms, bots, lungworms, intestinal threadworms and summer sores caused by Habronema and Draschia spp. cutaneous third-stage larvae. It removes worms and bots with a single dose. One syringe deworms horses up to 1,250 lbs (600 kg) body weight. The apple-flavored past is safe and effective on all horses including broodmares, stallions and foals. Horse Health (ivermectin paste) 1.87%.