Yellowstone is not high enough to worry about.
WRONG. W. Yellowstone is at 7,000 feet. The park has an average elevation of 8,000 feet. Yellowstone Lake is at 7,700 feet. High Altitude Pulmonary Edema (HAPE) can occur at as low as 5,000 feet depending on the individual. Animals and humans that have spent their lives at low elevations may have a harder time adapting than those who have lived at higher elevations their entire lives.
Mama, just take it slow the first couple of days and make sure puppy gets well hydrated (and you too!). Tell puppy no alcohol, either! :B