Zoetis QUEST PLUS Gel Moxidectin/Praziquantel Adult Horse Dewormer, a broad-spectrum dewormer is effective against tapeworms, encysted small strongyle larvae and bots, large strongyles, roundworms, pinworms, hairworms and stomach worms. The unique gel formula dissolves on your horse’s tongue to make deworming easier for you both. This dewormer is approved for use in breeding mares and stallions. Each syringe treats a horse up to 1,500 pounds and contains the active ingredients moxidectin and praziquntel.