I hiked in 2002 with a Lab/Dane mix. She weighs about 90 pounds and was 18 months old at the start. I had my father bring her to me after the Smokies and she hiked to Harpers Ferry where I thought the heat was going to kill both of us...Dad came and picked her up again. I brought her back out for VT and NH. She covered about 1000 miles that summer and has been the best dog I've ever owned which I credit to the hike. I wouldn't say it's impossible...but be ready to change plans based on the dogs needs. If you do bring the dog make sure it has seen some miles before you get out there....Don't let anyone other than a Vet tell you not to do it either.