The Collar–Cancer Connection: What I Have Seen for 20 Years, and What Science Just Confirmed

I want to talk to you about something that took me two decades of practice to fully understand — and that I believe is one of the most overlooked reasons dogs develop cancer. It starts with something as ordinary as a collar and a leash. I know that might sound surprising. But stay with me, because this is no longer just my clinical observation. In 2025, researchers confirmed what I have been seeing in my patients for twenty years: the nervous system plays a direct, active role in whether cancer starts, grows, and spreads in the body. And the neck, the very place a collar sits, is one of the most important parts of that system. A Pattern I Kept Seeing When you practice integrative veterinary medicine long enough, certain patterns become impossible to ignore. I started noticing years ago that dogs coming in with tumors in different parts of the body had something in common: a history of injury in the neck from collars or back pain in general. The breeds I was seeing this in most often? Labs, Golden Retrievers, German Shepherds, Rottweilers. These are also the breeds most likely to be strong pullers on a leash. Coincidence? I stopped believing that a long time ago. The connection betw...