Tough Mudder and Chewy Partner to Bring Ruff Mudder to Dogs Across the Country. Ruff Mudder is an all-dog version of the popular Tough Mudder event in which participants test their physical and mental limits by navigating a mud-soaked obstacle course. Guided on-leash by their trusty pet parent, four-legged participants will face seven obstacles to crawl and climb their way through. Chewy’s partnership with Ruff Mudder centers around a shared focus on active lifestyle and building camaraderie and connections, whether between people or people and animals. This event celebrates the special relationship between people and pets in a fun, exciting and interactive way.