An unsound dog tires easily because it wastes energy bouncing up and down instead of covering a lot of ground with just a few, efficient steps. Gameness, a lot of heart, and sharp instincts will carry an unsound dog for only so long. In time, the unsound dog will become uncomfortable, perhaps live in pain. This applies to any dog, not just working dogs, and not just purebred dogs. The dog who loves to play fetch is also impacted by how it is built.
Much of what we know about what makes a dog “sound” comes from the horse world. Horsemen from “back in the day” knew that a horse with a steep shoulders (what dog people call “angulation”) made for an uncomfortable, bouncy ride.
We want to begin explaining what makes a sound dog, well, sound. We’ll take baby steps, and we encourage you to grope your dog as you learn about his innards. It’ll be fun!