If your dog isn't under reliable voice control you would be doing him and the public a favor by leashing him. Your dog may be cute, friendly and well-behaved, but if hikers have to constantly detour around piles of poop on the trail they will resent him. Clean up after you dog. Carry a plastic bag and pack it out, or carry a trowel and bury it. Hiking in the desert in hot weather can be fun, but careful planning is essential.
Water is the biggest problem.
Both you and your dog should drink lots of water before and during the hike. Get a doggy back pack and let Fido carry his own water. The first sign of heat exhaustion is uncontrollable panting. If you suspect that your dog is suffering from heat exhaustion wet down his coat with all the water you can spare and get him to a vet as soon as possible. Rattlesnakes are plentiful in the foothills around Salt Lake City.