I am unsure as to what kind of service/therapy dog we're referring to.
Cooper is both, although he's called an "assistance" dog since he's not fully "certified" as a service pooch. To enroll him in service dog classes, he had to take prerequisites including basic obedience, Canine Good Citizen (obedience II), and agility before he could enroll. He took the first set of classes which are learning to retrieve things inside the home, dialing 911 and opening the door for EMS. After that training, I noticed that he started to act funny when I would have MS attacks, whether they were little tiny attacks or really bad ones. Somehow, he picked up on them all by himself and now, when he senses it, he will stand by my side, waiting for me to say "phone" - telling him to dial 911. Cindie saw that behavior this weekend, in fact. LOL
He's also a therapy dog, working with senior citizens at retirement homes and hospitals. He had to go through a battery of temperment tests before he was accepted. Your dog can't be a licker - they can give kisses but they can't be a licking machine if they go into places where sick people will be in contact with them. I actually had to train Cooper to NOT lick people unless told - that was harder than it sounds LOL
There are tons of sites on the internet about service & therapy dogs. Depending on where you live, you should be able to find a facility that trains dogs for hearing and visually impaired people to be able to get more information.
Good luck!