Arthritis is a painful condition
Sure your dog is not howling in pain but dogs aren’t like that. They might be wagging their tails looking to you for attention but that doesn’t mean they are not in pain.
Make no mistake about it, If your dog limps or is stiff when they get up they are in pain!
Because dogs walk on 4 limbs not 2 it takes a lot more pain for them to limp than it does for us to limp. By the time they become lame they are at a much advanced level of degeneration than us weak 2-legged animals.