Some dogs just look the part, thick neck, wide chest, powerful back legs as if they’ve spent the day sprinting through fields. You watch them trotting down the street, pulling their on the leash owner the way they might drag a sled and you have to do a double take. And it’s not just the big ones. Sure, pit bulls and boxers are common culprits, but even a little dog like a Staffordshire bull terrier can read as though it were made from a block of muscle. When they walk their shoulders pop. Their thighs are mobile when they sit.

It’s not even training, necessarily. Some dogs are simply made that way. They chase stuff, climb stuff, jump in the car on their own. The muscles seem to arrive on their own, even if they live in tiny apartments and nothing special ever happens. Genetics can be weird like that some bodies pile muscle on just by moving around, while others don’t seem to move the needle no matter how active they are.

But then there are the canine soldiers who do train, in another sense. Dogs that pull carts or trot a mile every morning alongside their owners. Working dogs like the sheepherd that patrols fields.

Their bodies tell the story of their work. Sometimes, they scarcely resemble pets at all. They have the appearance of small athletes grave and in training, even when lying in the grass gnawing on a stick.