That “extra” toe sitting higher up on your dog’s leg is called a dewclaw, and it’s not really extra at all. It’s the remnant of what was once a fully functional fifth digit in dogs’ ancient ancestors. On the front legs, it still serves real purposes: stabilizing the wrist during fast turns, gripping toys and bones, and providing traction on slippery surfaces. On the back legs, the story is different.
What Dewclaws Actually Are
A dewclaw is essentially your dog’s thumb. On the front legs, it’s attached to the leg by tendons, ligaments, and bone, with its own blood supply and nerve endings. If you’ve ever watched your dog hold a chew toy between its front paws, you’ve seen the dewclaw in action, curling inward to grip just like a thumb would.
Most dogs have dewclaws on both front legs. Some also have them on the back legs, and a few breeds carry double dewclaws on each hind foot. The front ones are nearly universal across all dogs, wolves, and other canids. The rear ones are far more variable and tell a different evolutionary story.
How Dewclaws Help Dogs Move
When dogs run, their front feet bend enough that the dewclaw makes contact with the ground. At high speeds, especially during sharp turns, the dewclaw digs in and provides extra traction while stabilizing the wrist joint. Without it, the leg would be more prone to twisting under the force of a sudden direction change. Fast breeds like Whippets and Border Collies rely on their dewclaws to navigate corners at speed.
The benefits go beyond running. Dewclaws help dogs scramble over rocky or steep terrain, climb out of water, and maintain grip on icy surfaces. Dogs in agility competitions use them to steady themselves on obstacles like the teeter-totter, grasping the sides with that inner toe. Removing front dewclaws can actually increase the risk of wrist injuries, since the joint loses one of its natural stabilizers.
Why the Rear Dewclaw Is Different
Rear dewclaws are a completely different situation. The canine species, including wolves and jackals, evolved to have only four digits on the hind limbs. The first toe was lost during that evolutionary process. When a rear dewclaw appears on a modern dog, it’s a developmental trait that essentially restores that lost digit.
Unlike front dewclaws, rear dewclaws typically don’t connect to the skeleton at all. They sit inside a flap of skin that protrudes from the leg, with no bone or muscle linking them to the rest of the limb. They dangle loosely and serve no mechanical function. Rare exceptions exist where a rear dewclaw has skeletal and muscular attachment, but for most dogs, these are purely vestigial.
Breeds With Double Dewclaws
Some breeds were selectively bred to keep their rear dewclaws, and a handful carry two on each hind leg. The Great Pyrenees is the most well-known example. These mountain livestock guardian dogs have double rear dewclaws as part of their breed standard, meaning show dogs are expected to have them. The Beauceron, Briard, and Icelandic Sheepdog also carry rear dewclaws as a breed trait.
In these working breeds, the extra toes likely offered some advantage on the rough, mountainous terrain where they were originally used. Whether the rear dewclaws in these breeds have stronger skeletal attachment than in other dogs is debated, but the trait was valued enough by breeders to become a defining characteristic.
Keeping Dewclaws Healthy
Because dewclaws sit higher on the leg and don’t contact the ground during normal walking, they don’t wear down the way your dog’s other nails do. That makes them prone to overgrowing, curling, and eventually snagging on things during play or running. A caught dewclaw can crack, bend, or tear away entirely, which causes significant bleeding and pain.
Signs of a dewclaw injury include sudden bleeding from the paw, limping or holding the paw up, excessive licking around the area, or a visibly bent or loose nail. If bacteria get into a torn or broken dewclaw, infection can follow. Regular trimming is the simplest way to prevent these problems. Some dogs need their dewclaws clipped every few weeks, while others wear them down more naturally. Checking your dog’s paws regularly for overgrown or cracked dewclaws catches small issues before they become painful ones.
Loose rear dewclaws that have no bone attachment are more vulnerable to snagging and tearing than firmly connected front dewclaws. For breeds where rear dewclaws aren’t part of the standard, some veterinarians recommend removing them early in life to prevent repeated injuries. Front dewclaws, because they’re functional and structurally integrated, are increasingly left intact.