You may have noticed the thumb-like toe on the inside of your dog's or cat's paw and wondered why it is there. Do dewclaws have a purpose or are they simply leftovers from evolution?
What Are Dewclaws?
A dewclaw is a non-weight-bearing toe on an animal's paw located on the inside of the leg near the carpus ("wrist" area). Dewclaws slightly resemble human thumbs but they do not have the same functionality. Dogs and cats are typically born with two front dewclaws, but some may have one or more dewclaws on the rear limbs as well.
Dewclaws contain nerves, blood vessels, and a nail that grows just like the other toenails. The dewclaw usually contains bones, is firmly attached to the leg, and can be slightly moved by the animal. However, some dewclaws—especially rear dewclaws in dogs—contain no bones and appear to hang from the side of the leg. The nail grows as normal, but there is no bony attachment and no motor function in the digit.
What Is the Purpose of Dewclaws?
Some people may think that front dewclaws serve no purpose for today's dogs and cats. After all, dogs and cats without dewclaws do not seem to experience limitations. While the dewclaws are not essential, they can be quite useful for many reasons. Dewclaws can help dogs and cats dig, climb, and hold objects or prey. When dogs run, their dewclaws make some contact with the ground and can serve to stabilize the carpus. Watch a dog or cat handling a toy or treat, and you may notice the use of the dewclaws to stabilize the object.
Rear dewclaws are another matter. These are considered vestigial structures that serve no function for dogs and cats. Rear dewclaws are present at birth and occur due to a genetic trait. Dog breeds like the Great Pyrenees and Beauceron are born with one or more rear dewclaws; this is actually part of the breed standard. Mixed breed dogs may be born with rear dewclaws as well. Polydactyl cats have a genetic mutation that causes them to be born with several extra toes, often including extra dewclaws.
Should Dewclaws Be Removed?
Some dog breeders remove puppies' dewclaws and dock their tails around 5-7 days old. This may be done because of the belief that the dewclaws serve no purpose and may become injured. It is also sometimes done to create a cleaner look for the show ring and to conform to breed standards.
Although dewclaw injuries may occur, they are not typically serious and may be avoided by keeping the nails trimmed short. Many vets are moving away from the practice of dewclaw removal in young puppies and prefer to let dogs keep these potentially useful digits. However, don't worry if your dog has already had his dewclaws removed; this will not limit them in any significant way.
Detached dewclaws in dogs may be removed during spay or neuter surgery to avoid future injuries. These floppy dewclaws are more likely to get injured than attached dewclaws.
Cat dewclaw removal is not typically done unless it is part of a complete declaw surgery. Feline declawing is the amputation of the last bones of the toes that contain the nails. This is a major surgery for cats and many experts now advise against it in favor of more humane alternatives.
Dewclaw Problems in Dogs and Cats
Dewclaws often cause no problems for dogs and cats. However, there are situations when nail problems occur. Most commonly, dewclaws may grow too long, curve, and grow into the skin of the paw pad. This can lead to pain, inflammation, and infection.
Dewclaws may get caught on objects like rocks, plants, and bedding, especially if the nails are too long. This is more common in dogs and may occur while they are running and playing. If a toenail gets caught on something, it may tear the nail or even fracture the toe. Detached dewclaws are more likely to snag on something and cause injury because the digit has no motor function and hangs freely.
Most dewclaw problems can be avoided by checking the nails regularly and trimming the nails as needed. Learn how to trim dog nails and how to trim cat nails so you can keep your pet's nails healthy. Contact your veterinarian if you have any concerns about your pet's dewclaws.