Heidi has HD and arthritis and her vet said walking and swimming are the best exercise for her. Hiking is fine. We walk the four miles around the lake near our house pretty frequently and Heidi does fine with that, but I was wondering how much farther she would be ok with walking. So Sunday we took to the trails and went about six miles. By the time we returned to our car, Heidi was walking slower and slower and seemed to be limping a tiny bit. When we got home, she seemed happy, but went straight to her crate for a long nap. I think if we do that hike again, we will bring our lunch and take a LONG break in the middle. Any comments about how much walking is too much for a dog with arthritis?