As of 2010 (a while ago, but the last time this came up on tripadvisor) there were no dog daycare facilities in West Yellowstone. You might inquire at campgrounds if they have a dog-walking service; otherwise if the dog will be ok in the camper while you are away for the day driving a car/truck around the park, that would be your best option. As others have pointed out, dogs, even on a leash, are usually not allowed on the boardwalks. There have been a few instances of dogs getting away from their people in the park, and that's a scenario you do NOT want. Lots of dangers to them in YNP (to people too, but most of us can reason enough to realize that and avoid the danger). Good luck!
