Strongid Paste Pyrantel Pamoate Horse Dewormer is a broad-spectrum horse dewormer that’s effective against a variety of internal parasites. The active ingredient, pyrantel pamoate, helps to control and remove large strongyles, small strongyles, roundworms and pinworms. Each syringe treats up to 1,200 pounds of body weight, and the oral paste is convenient to administer. This dewormer is safe for use in breeding, pregnant and lactating mares, as well as in young foals.