What is the Purpose of a Dog's Dew Claw?

By Linda Cole

Dogs have a toenail located on the inside part of their front leg that's called a dew claw. Most dog owners know where it's located and remember to clip it at the same time the rest of the dog's toenails are trimmed. If this nail is left untrimmed, it can cause pain and damage to the dog's leg. Some dog breeds have dew claws on their back legs as well. What is the purpose of a dog's dew claw, and why do some breeds have them on their back feet?

Because a dog's dew claw is located up on his leg, when he walks through the grass in the morning before the dew has vanished, the claw skims along the top of the grass. And that's how the dew claw got its name.

Not all dogs are born with dew claws, some only have the toenail on the front leg and other breeds have them on all four legs. Some breeds can have two dew claws on one or more legs. When a dog has a double claw on a leg, it's called polydactyl. Some dog breeds are required to have back dew claws if they are being shown in the ring because it's part of the standard for that breed.

Although not all dogs use their dew claw, they do have a purpose. It's sort of like our thumb, and some dogs use it to hold onto bones, toys, balls or other things they play with or chew on. Two of my dogs can control the toenail well enough to dig food out from between their teeth. They will scratch their nose or corner of their eye with it and one uses her dew claw to scratch inside her ear like we would use a finger.

Some rare dog breeds like the Basenji (pictured above), the New Guinea Singing Dog and the Catahoula Leopard Dog are able to climb trees almost as well as a cat, and they use their dew claws to grasp the tree bark as they climb. Other dogs bred to hunt have also been known to climb trees after their quarry has been treed.

The dew claw is classified as another toe and does need to be trimmed just like the other toenails. Because of the position of the claw, left untrimmed, it can curve down so much it becomes ingrown and puts the dog at risk for infection. Most dew claws are not down far enough on the dog's leg to make contact with the ground which gives the nail no way to be worn down naturally. It's important to keep these claws trimmed regularly, especially back ones. Left untrimmed, the quick will also grow longer which will make it harder to keep the toenails properly trimmed. Dew claws that are too long can make it easier for the dog to catch one in the brush when he's running around outside while working or playing. This can result in a torn toe.

Back dew claws are more common in breeds like the Great Pyrenees, Saint Bernard and Briard. It's believed the toenail on the back legs of the Great Pyrenees and other dogs that were bred to work in snow or rough terrain aids them as they do their job by giving them better stability as they run over the rough ground or make sharp turns.

The dew claw is attached to the leg with muscle and bone, although not all dew claws have bone in them. Sometimes the toe is attached loosely to the leg and when the dog runs, the toenail can become caught and easily torn. The back dew claw may need to be removed if it's loose or has been torn to avoid more injury to the dog's back feet.

For most dogs, the dew claw serves no particular purpose, but it still needs to be attended to just like the other toenails. It's easy to forget them, especially on long haired dogs where the hair covers the toe. Even though most dogs don't use the toe, sometimes they do and it may be more useful to the dog than we realize.

Trimming your dog's toenails regularly can help keep them at the proper length. A good time to do that is when you groom your pet. Ruthie Bently’s article on basic grooming supplies and procedures has excellent information on how to groom your dog.

Read more articles by Linda Cole