We have an elderly Devon Rex (16) who has lost a lot of weight over the last year or two - fully investigated by the vet, and probably has severe malabsorption problem, but otherwise OK and we've decided to just let him eat whatever he wants and carry on. He is lively as a cricket, still doing all his usual stuff. He lives upstairs (always been an indoor cat) with plenty of human company and our rescue dog, who is terrified of stairs (handy) lives downstairs.
Until recently, this arrangement worked well for all concerned, but a few months ago, cat decided to start coming downstairs again, and had an unfortunate encounter with dog, during which I was convinced that he had been severely mauled. When I eventually found him, it turned out he was unharmed, but had been slobbered on pretty comprehensively!
We put up a barrier at the top of the stairs to prevent a repeat and again, all settled down. Two days ago, I was standing in the hall and there was a tremendous crash - cat had launched himself from the upstairs landing and jumped down about 8 feet on to the middle of the stairs. Quite unconcerned, just started yelling at me for food and then disappeared back upstairs. We improved and extended the barrier, and then today, he managed to bypass it entirely and we had a repeat performance from an added height (he'd got up on to the table on the landing and gone over the top of the bannisters.)
As my daughter put it, this is not a cat who is feeling his age. Anyone else had a cat suddenly morph into a feline Eval Keneval? He seems quite unharmed by his adventures and there are no other signs of confusion or dementia or whatever. I'm just baffled by the sudden stunt activity!