This is terrible. I'm so sorry. I am not very well informed on this stuff, but my understanding is that these systemic flea products are in general pretty safe as long as they're in the correct dosage, and that a dog product isn't given to cats. If you had the correct product and used it according to the directions, something is wrong with the product and you should have recourse. But even if you were wronged, getting a corporation to acknowledge that they were at fault is probably tilting at a windmill.