It’s less safe to hike with just a leash and collar, says Callery. “Flat collars offer only a very small area of contact, which sits directly on one of the most sensitive and delicate areas of a dog’s body (the neck and trachea area),” Callery says. “In case of emergency or unforeseen falls or stumbles, a harness would offer more safety, with the pressure being spread across multiple points of contact.”