Oh, Sky, is there no way you can take him with you? They may understand that since he's a service dog he hould be with you at all times, and especially since he is so well trained would be no trouble at a clinic, and may even bring some joy to people while there. Or is it more that you worry about traveling with him, how that would affect him because of his age? I hope you can figure something out that's good for both of you.