They can die of heat exhaustion in a very short time. There are many areas outside of Arches where pets can accompany hikers, bikers and other groups.
More information is available at all area visitor centers.
Pets Activities with pets are very limited at Arches. Pets are prohibited from the backcountry as well as on hiking trails. Pets may be walked on roads or in parking lots, but must be leashed at all times when outside a vehicle.