Almost every dog in the world learned to walk on a collar, and most of them are fine. So why does every trainer, vet and behaviourist now say to use a harness? Because "most of them are fine" is doing a lot of work in that sentence.
What a collar does under load
When a dog pulls against a collar, all the force concentrates on a band about two centimetres wide, wrapped around the throat. Underneath that band sit the trachea, the thyroid, the jugular veins and the nerves running to the front legs.
A single hard lunge is unlikely to do lasting damage to a healthy adult dog. The problem is repetition: a dog that pulls for twenty minutes a day, every day, for years. Vets link chronic collar pressure to tracheal irritation and, in small breeds, to collapsed trachea — which is why toy breeds should essentially never be walked on a collar.
What a harness does differently
A harness moves the load onto the chest and shoulders: a much larger surface, backed by muscle and bone rather than cartilage and blood vessels. The same pull that concentrates on a dog's throat is spread across an area ten to twenty times bigger.
That's the safety argument, and it's the strong one. The training argument is separate.
Does a harness stop pulling?
Honestly: not on its own, and anyone who tells you otherwise is selling something. A harness makes pulling safe. It doesn't make it stop.
What actually reduces pulling is the opposition reflex — dogs instinctively push against pressure. Front-clip harnesses work with this by turning the dog gently sideways when it pulls, which interrupts the forward momentum rather than fighting it. Combine that with stopping every time the lead goes tight, and you get change in a couple of weeks. The harness is the tool; the stopping is the training.
What about the "harnesses encourage pulling" argument?
You'll hear that harnesses are what sled dogs wear, so they teach dogs to pull. Sled harnesses are back-clip, designed to let a dog lean into a load with its full body weight. That is a different object from a padded walking harness with chest adjustment. The shape does the work, not the category.
Where the collar still belongs
On the dog, all the time, carrying an ID tag and a tracker. That's what a collar is genuinely good at. The lead goes on the harness.
The Comfort Pro Padded Harness spreads the load across the chest with padding where the straps meet the body, and adjusts at both neck and chest so it stays put on a dog that leans.