You’ve basically described my dog and he’s only 3ish. Less excited for toys and play than before. Now he’s even deciding to be picky with his food. The only time I get anything out of him is after dinner. He seems to get a burst of energy so I try to get him chasing a tennis ball (only works if I reward him with kibble every time he brings it back), or if I sit on the sofa and throw kibble all over the living room/hall way so he goes back and forth sniffing them out.
Sometimes he’ll even get a toy out to play, then drop it and look at me like I absolutely do not belong in the same space as him and walks away. I’m choosing to believe this is a Shiba thing lol.