If you had a hunting dog, when would you retire it?

I friend of mine has a Son that has a German Shorthaired Pointer. Heidi is 12 years old and has been hunting most of her life. She gets very excited to go hunting, even in her old age, but the last time she went out with Scott, she ended up getting lost for almost a 1/2 hour. From my understanding, her eye sight and hearing is failing slightly, but somehow she found her way back to his vehicle. Would you say that this is the time for Heidi to stay home and nap in front of the fireplace, or would you still be taking her out because she gets all geared up when Scott puts his gear on? I guess I would retire her as I would be worried about her safety. They have a new GSP b*tch, that is about a year old now, that the wife insisting on getting from a breeder friend of hers. From what I've heard, they've had to hire a trainer as she is as dumb as a bag of rocks with no hunting instinct. I don't know if that can be *trained*, but it sure doesn't look like it. So, would you let the old lady home, for her safety, or continue to take her out because she still loves it?