Vestigial features are when certain parts of the anatomy are present without serving any real purpose. Many creatures (including humans) have them. After all, nobody really needs an appendix. Also consider the fact that many flightless birds (such as ostriches, emus, and kiwis) still have wings. When it comes to your dog's dewclaw (the inward-facing claw slightly above where the leg meets the paw), there's some debate about whether the feature is actually vestigial. However, given its unique location, the dewclaw can easily be damaged.
When a dog is running at speed or climbing onto something, the dewclaw can serve a purpose by providing extra traction. However, the dewclaw doesn't make regular contact with the ground during most activities. Its slight elevation can make it prone to being caught and subsequently becoming injured.
Bleeding and Discomfort
A dewclaw injury can be extremely distressing for your dog. In some cases, the nail can be torn off. Because the nail has its own blood vessel with nerve endings, such an injury can result in heavy bleeding, as well as considerable discomfort. This type of injury warrants an urgent trip to your vet.
Treating dewclaw trauma can require one of the more basic veterinary surgical services for dogs, which is the surgical removal of the affected dewclaw. Vestigial or not, your dog won't miss the claw if it doesn't regrow. The removal is quick and easy and is usually performed under a local anesthetic.
Managing the Injury
Depending on the severity of the injury and whether the tear was complete or partial, the dewclaw may grow back. Antibiotics are generally required, and these will be provided when the injury is treated. You must keep the affected part of your dog's claw as clean as possible while your dog recovers, and if your dog interferes with their bandage, an Elizabethan collar (also known as a pet cone) can be helpful.
Moving forward, should the dewclaw regrow, it's important to have it trimmed as part of your dog's regular grooming. Due to the lack of contact with the ground, it's common for dewclaws to become overgrown, which increases the odds of the claw snagging on something and becoming injured. If you and your dog ever have to deal with a dewclaw injury, you won't want to repeat the experience.
Dewclaw injuries can be painful and if left untreated, can become infected. It's the type of injury that should be attended to without delay. Reach out to a professional for veterinary surgical services if you think your dog needs it removed.