A dew claw is that vestigial ‘finger’ that grows above a dog’s paw. They may not contain bone, but aren’t simply loose skin, however. Beneath the fur, five tendons attach to muscle.
What are Dew Claws for?
In most biological species, tendons are meant to attach muscle to bone; when the muscle contracts, it pulls on the bone and creates movement. This very simple biological truth means, where as a dog’s dew claws may not seem to have a use now, they once almost certainly contained bone and did serve a purpose, which dogs/wolves likely evolved out.
At least that is my educated guess, having studied the same animal biology & physiology as any licensed technician, as well as the human anatomy and physiology. Still, the fact remains; I can’t say for sure what a dew claw’s purpose is.
So, let’s conduct a little survey! By contacting (attempting to) several veterinarians, hopefully we can determine the exact purpose of the Canine Dew Claw.
I didn’t even get past the tech with this one. Her answer amounted to the original purpose of Canine dew claws being to hold prey. My thoughts here– this must have been a very, very long time ago, because any dew claw would easily tear if a dog or wolf tried to hold another squirming animal with it. With no bony tissue or tendentious connections for support…
In the end, this may have once been a purpose, but certainly no longer. What do you think? Please, let me know in the comment section below!
Veterinarian two is actually Veterinarian four; the last two were ‘in a meeting, and unavailable’ (which means they couldn’t answer the question, and didn’t want to discredit themselves). The fact that a highly educated doctor can’t answer a medical question related to the animals they deal with on a daily basis is very interesting.
In any case, this veterinarian gave a slightly different answer; the biological purpose of dew claws, in the wild, is to grip bones of a kill. This makes more sense, seeing as a dead animal won’t be moving, and there is no chance of the claw tearing.
Still, to establish a good ‘grip’, it would make more sense biologically if bone were to accompany the dewclaw- which it doesn’t.
This one was a bit different; the tech answered: to assist the dog in climbing. I find that doubtful, because dog’s don’t climb like cats do. At least she gave an attempt; the far more educated doctor simply said: “That is how they are made”!
I actually consulted a scientific article written by a DVM for this one. This article gave a very different explanation: the muscles of a dew claw are meant to prevent unnecessary torque on the leg. Without breaking down the physiology, this does make sense; feel free to read the short article if you’re up to it.
In all, I contacted eight sources, including the veterinary school at Cornell University; only two gave me credible answers (not including the paper). Do you have any other thoughts?