While the position of a dog’s dewclaw—separated from the rest of their digits—makes it look like the canine version of a thumb, they don’t exactly use it to hold a beer, indicate approval, or do anything else our thumbs do. You may have even assumed dewclaws did nothing at all.

They do, however, serve a purpose. Read on to find out what that is (and what the verdict is on dewclaw removal).

What Is a Dewclaw?

The word dewclaw describes a digit that doesn’t touch the ground, which is found on the feet of dogs, cats, and other mammals.

Most dogs only have them on their front feet, but a few breeds—including Great Pyrenees and Briards—also have them on their hind feet. As PetMD explains, front dewclaws have less mobility, because they’re attached by tendons and bone; whereas back dewclaws sometimes hang on by skin alone.

What’s the Purpose of a Dewclaw?

Though not as versatile as our opposable thumbs, dogs’ front dewclaws are essentially their thumbs (and back dewclaws are their big toes). Some mammals have evolved out of using their dewclaws, but dogs’ front dewclaws aren’t completely vestigial.

“When dogs run, their front feet often bend to the point where their dewclaws come in contact with the ground. At high speeds (especially when turning) or on slippery surfaces, these dewclaws provide extra traction and help stabilize the carpal (wrist) joint,” veterinarian Jennifer Coates writes for PetMD.

The grip and traction provided by dewclaws can also come in handy when a dog needs to hold something in place (like food or a toy), climb a tree, or hoist themselves from water. Back dewclaws connected by skin, on the other hand, are too wobbly to serve any clear purpose that we know of.

Should You Remove a Dog’s Dewclaw?

Because front dewclaws have an important function, experts generally advise against removing them except in special situations, such as if there’s a tumor growing on one. Some people want to remove their dog's flimsy back dewclaws so they don’t have to worry about the pup getting snagged on something and causing injury. But since this isn’t exactly a rampant issue to begin with, some argue that the surgery is unnecessary or even unethical. Your best bet to prevent dewclaws from causing any issues is to keep the nails short and well-maintained, rather than doing away with the claws altogether. That said, it's always good to get your vet's opinion, too.