I would treat him much like you would an older human and take him out well wrapped in a heavy-duty fleece doggy coat. The walk, even just a very short one, will probably do him more good than harm and lift his spirits. 15 years is a great age, so why not let him have exactly what he wants while you can give it to him - and all dogs love going for walks, so if it were me, I'd let him have the walk. Tony
Let him do what he needs to do. A dog who doesn't want to go out will certainly let you know, by either hanging back, or giving you that sad-eyed "you cannot be serious about going out there" look. Many dogs are quite happy at below freezing temperatures, so long as they are not standing around chilled, and if they have long haired coats they like the colder weather. Like Tony said, if your dog does feel the cold or if he's short haired, get him a good fleece lined dog coat and he'll be fine.
I find dogs will tell you when they want to go, and will tell you when they've had enough and want to go home.
My dog is approximately 14 and there is no keeping her in. The outside is her world. The only thing that stops her is torrential rain. That's their life, if they are built for it. Some don't ever want to "retire"!
I agree with tonyb286, at that age let him do what he wants and what makes him happy, only don't over do it. You might find his feet get overly cold and he starts limping, our dog used to, so we had to carry her back. I think she used to enjoy that part the most.
Let your dog be the judge. Pay close attention to how he is acting after his outdoor excursions. If he seems uncomfortable, stiff, or sore...then he over did it. Even old dogs with bad joints, need some type of exercise and he may really enjoy the cool crisp air and all the scents that are carried on it. Giving him a chance to get outside will not only stimulate his senses, but will also help keep him limber. Again, just pay close attention..if he seems cold, get him a coat and possibly some boots ....keep an eye on how long he stays outside, how cold it is, how far you walk him...etc....and adjust his time outside accordingly. If you are mindful, you will soon know how much he can comfortably tolerate.
I live in Northern Minnesota...I know how cold it can get, but I also know how much my dogs love to go outside, Many times, all they do is stand out there and sniff the air for 1 or 2 minutes..they seem to LOVE IT...They always come back in the house more alert than when they left, and with renewed sense of vigor..!
Quite honestly....so do I...!
I know that's true Connie.
Last year we had very low temperatures where I live, well below freezing, maybe minus 10-15 sometimes with some serious wind chill. Yet my dog seemed quite content in it! Moreso than she would be in rain. But I knew that if she stopped moving around she would feel it, so had a thin snug-fitting coat I put on her with a thin fleece lining, for her to run in.
I watched her. If she started to pant I took off the coat, while she was running or exercising. I watched the hair on her back.Because she is short haired, whenever she is a little cold, hair stands up a little in a certain pattern down her back. If I saw this happen I would put the coat back on.
Then when we got back from running, and I was doing any outside work like chopping logs etc, then she was standing about under the bird table. I then put an extra fleece-lined coat on top of the other one, for when she was not exercising. The two together really did trap some warm air, and when I put my hand against her back to see if she was ok, she was lovely and cozy!
The one important thing to watch with any dog -young or old- in freezing weather, particularly if there is snow -is snow collecting on their feet and freezing there, as the ice crystals can cut the sensitive skin between their pads.