My parent's oldest will be 13 this year. He's on arthritis medication. However, he still does his best "wiggle, bend, wiggle, bend, slurp, drool, slurp" everytime he sees someone.
That's a pretty good age for a Boxer. It's funny how they never change. All other dogs actually grow up, but Boxers remain puppies their whole lives.
I bet he has gray all over his head and face. Old gray Boxers are noble and adorable (and easier to catch if they run out the front door).
Mine tested positive for heart worms and stayed at the vet for three days last week. He didn't care for that at all, and he was a little slower for a few days. He's back to his old self, now.