Until he was around 10 years old he was more or less the same dog, and suddenly round 11 years old I could see a small change. Slowing down a bit, but still following me on long hikes in the morning, and really just the best dog.
After he turned 12 years old, he was injured, nothing bad but still changed a lot, and after a couple of months he was okay again, but really never the same as before the injury. His body was older, but his mind was still the same, and I saw how his body could not follow his mind, and that was, and still can be hard to watch. He is still a happy dog, and still playful and so funny. But he is very old.