"If you are disabled as defined by the ADA, that is, if you have a condition that substantually limits a life function, and your dog does one thing for you, like picking up dropped items, or helping you walk by supporting you, or responding to a medical condition in a manner that you trained, then your dog IS a service dog. Certification is not required. If you are unsure if your dog is a service dog, please call me, and I'll give you my expert opinion on the matter."
http://sdog.danawheels.net/ot-adog.shtml