Dog and I have returned from our hike on the West Rim Trail. We did not complete the entire 30 mile hike. Dog got a cut on his shoulder near where the pack rides and is missing a patch of skin around it. At first I wasn't sure if the pack caused the cut/rub or if he was cut by the sharp ends of blueberry bush twigs along part of the trail. I discovered the injury our second night out and decided to try and make contact with the shuttle the next morning.
I wanted Dog to enjoy his adventure, and I was concerned that the minor injury would worsen. If that happened, I'd have a limping unhappy 70 lb dog with no way to get him out. What really decided me was that the next morning he didn't want to eat his breakfast, and I know the first sign of a dog working too hard is that they don't want to eat. So I was luckily able to make cellphone contact with the shuttle at the Bradley Wales picnic area, and they came and retrieved us.
Dog slept for the next 2 days. I will give a more detailed trip report later--perhaps even starting it later today.