No. While your dog may not need a harness, many veterinarians recommend you use them. And they are generally a lot nicer. The last time I took Finn, my 1-year-old, into the vet, I left his harness at home and attached the leash to his collar. He was so excited to see other dogs he was repeatedly choking himself on the collar. The technicians recommended more than once that I use a harness to keep him more under control and create a safer environment for him. The downside of harnesses for dogs who pull, is if you attach the leash to the back of the harness, it allows them to use their full body strength to pull on you, much like a sled dog. But even that, if you’re prepared, is better for the dog than a collar. And if you have a dog who pulls, attach the leash to the chest loop.