Actual rat poison is not suitable as pet food and presumably would have no concern as chametz, even to warrant sale by those who sell products that have a slight risk of chametz content (see here; see also here and here). RatX pellets, however, are marketed as an all-natural, non-toxic rodent killer. There mechanism appears to be less as an actual "poison" and more as a deliberate mechanism to dehydrate rodents based on their specific behaviors and biology - specifically by causing them to dehydrate when they are not provided with alternate sources of food and water. Accordingly, the product seems to be fairly safe for humans and pets, and does not seem to be that distinct from, say, a salty corn and wheat snack food. The "active ingredients" are listed as: corn gluten meal and salt (sodium chloride), and the "inert ingredients" are: matodextrin, sorbitol, wheat flour, and wheat germ oil. As such, could they be considered chametz?