Before buying any pet flea and tick product over the Internet or in stores, you should always make sure that the product is registered by EPA and that the label shows the EPA registration number. For information on counterfeit pet products, see
You should also make sure that you are purchasing a product that is registered for use on cats if you have a cat and that is registered for use on dogs if you have a dog. The products are not interchangeable, and using dog products on cats, especially, can be fatal. Also, do not purchase pet spot-on products that come in a large size (i.e., are registered for use on a large animal) from which you have to fill a smaller syringe to dose your pet. This is illegal.