They usually can't tolerate heat, cold or brisk exercise like they used to. I recommend to take it easier with an older dog, consider they are having issues with arthritis and mental decline just like some people do. Use steps for a small dog to get up and down from furniture like couch or bed. We had bought a ramp for our old dog, unfortunately his didn't live long enough to make use of it. Always bring water for the dog on any outdoor walks.
Know that their vision and hearing are likely impaired, when I was taking one of my older dogs to the dog park with my two younger ones years ago, although he always listened and responded to me when I called his name, he seemed to hear me, but not from the right direction. He was eagerly running the other way instead of toward me. Luckily he was friendly, and a nice lady was able to hold onto his collar until he saw me and was ready to come the right way.
Although he always reliably, on a daily basis, went to fetch the newspaper from the driveway, one day he started to look out of sorts, bypassed the paper, and started to stroll down the sidewalk, kind of in a daze. We knew then that dementia was setting in, and so we kept a watchful eye and made sure he wouldn't do something that would get him injured or in any trouble.
I'm a big fan of supplements, so giving an older dog something for joints and inflammation pain like Glucosamine, MSM, etc., is always a good idea.
My dog has developed intense separation anxiety since the loss of our other dog a couple of years ago. It's become a serious problem. At 11 pounds he's too small for most meds. We're trying a thunder-shirt but his anxiety pattern has become so ingrained that he still cries and paces while we're gone (we have internal and external security cameras). Any suggestions?
StarSong, have you tried to leave him with articles of clothing of yours when you're gone, something that hasn't been washed yet and still has your scent on it? Something that you don't care if it's on the floor and he lies on it. Also, leaving a radio on low volume on a talk show may help with the sound of people's voices for company. Good luck, I know I couldn't have a good time out, knowing one of my babies was stressed out and fearful at home.