Originally Posted by Fitter30
Just wondered if anyone took their dogs on a trip like this I've got two 50 lb collies
You can, but it's extremely restrictive and would be best to leave them with a trusted sitter:
Originally Posted by National Park System
Bringing a pet to Yellowstone may limit your activities in the park. Protect your pet and park wildlife by observing these regulations:
Pets may only accompany people in developed areas and must remain within 100 feet (30.5 meters) of roads, parking areas, and campgrounds.
Pets must be physically controlled at all times: they must be in a car, in a crate, or on a leash no more than six feet long.
Pets are not allowed on boardwalks, hiking trails, in the backcountry, or in thermal areas.
Pets may not be left unattended or tied to an object.
Pets may not be left in a situation where food, water, shade, ventilation, and other basic needs are inadequate. Pets may remain in vehicles for short periods of time, but we recommend that someone stay behind to personally ensure their well being.
Owners must bag and dispose of pet waste.
There are NO EXCEPTIONS to the regulations for carried pets (in arms, carriers, strollers, backpacks, and so forth) in restricted parts of the park.