The Americans with Disabilities Act (ADA) defines a service animal as any guide dog, signal dog, or other animal individually trained to provide assistance to an individual with a disability. If they meet this definition, animals are considered service animals under the ADA regardless of whether they have been licensed or certified by a state or local government.
Access the attached web linkat:
http://www.ada.gov/qasrvc.htm, for further Department of Justice guidance concerning service animals.