The Dewclaw Is Not a Leftover. But the Case for Keeping It Is Thinner Than You’ve Been Told.

For decades, breeders have snipped front dewclaws off three-day-old puppies as routine housekeeping. For the last decade, a counter-argument has swept through dog sport circles: dewclaws are functional, and removing them causes arthritis. The first position was never examined. The second has been repeated so often that almost nobody checks where it came from.

Start with the anatomy, because that part is settled

A front dewclaw is not a skin tag. It is digit one — a real toe, in the same sense that your thumb is a real finger.

It contains two bones, the proximal and distal phalanx. It has a joint. It has a blood supply and a nerve supply. And critically, it is anchored by tendons that run back to muscle bellies in the forearm.

This is where front and rear dewclaws part company. Rear dewclaws, where they exist at all, are frequently attached by little more than skin — they wobble loosely, have no meaningful muscular connection, and in most breeds are genuinely vestigial. Front dewclaws are built into the limb.

So the blunt version of the myth — dewclaws are useless evolutionary leftovers — is wrong for the front limb. That much is not in dispute.

How many tendons attach there is slightly less tidy than the internet suggests. The widely quoted figure of five tendons comes from veterinary sports medicine specialist Dr M. Christine Zink, citing Miller’s Guide to the Anatomy of Dogs. Other veterinary writers describing the same structure count four tendons and two muscles. The precise number varies with how you choose to count. The principle does not: this digit has muscular attachments, and structures with muscular attachments generally do something.

What the dewclaw appears to do

Three functions are regularly described. They rest on different quality of evidence, and it is worth being honest about which is which.

Traction and carpal stability. Zink examined slow-motion video of dogs at a canter and gallop and reported that the carpal pad and dewclaw make ground contact during the stride. When the dog turns at speed, she observed, the dewclaw digs in and braces the lower leg against twisting force.

This is the most important claimed function, and the most frequently repeated. It is also worth noting what it is: a specialist’s observation from video, not a force-plate or kinematic study. Nobody has yet measured how much load a dewclaw actually takes during a turn.

Object manipulation. Entirely uncontroversial. Watch any dog hold a bone or a chew toy and you will see the front dewclaws clamp down from the sides. This needs no study.

Climbing and self-rescue. Dogs have been observed using front dewclaws to haul themselves up slippery banks and, in widely circulated footage, out of broken ice. Compelling to watch, and plausible given the anatomy — but it is observational, not research.

Now the claim that needs correcting

Here is the line that appears in almost every dewclaw post on the internet:

Removing front dewclaws causes carpal arthritis later in life.

No peer-reviewed study has demonstrated this.

The origin of the claim is traceable. Zink reported that of more than thirty dogs she had treated for chronic carpal arthritis, only one had intact dewclaws. The rest had all had them removed.

That observation is interesting. It is not evidence of cause. It is an uncontrolled case series drawn from the patients of a sports medicine specialist — a population already selected for being injured. It carries no comparison group, no control for breed, workload, surface, age or conformation. Zink herself framed the arthritis link as reasoning from the anatomy, not as a demonstrated finding.

There is also an obvious counter-case that gets raised by veterinarians who work with hard-running dogs: sled dogs commonly have their dewclaws removed, work at extreme intensity over long distances, and do not show the elevated rates of carpal arthritis the theory would predict.

What the actual studies found — and where they disagree

Two survey studies have examined this. They reached different conclusions, and that disagreement is the real state of the science.

Sellon et al., 2018 — published in the Journal of the American Veterinary Medical Association — surveyed digit injuries in agility dogs, comparing 207 dogs with digit injuries against 874 without.

The findings:

Two things stand out. The dewclaw was the digit least likely to be hurt — which undercuts the main argument for removing it preventively. And its absence was associated with more injuries to the other toes.

Note carefully what this study measured: digit injuries. Not carpal arthritis.

The 2022 follow-up, published in Frontiers in Veterinary Science, surveyed 4,197 agility dogs — roughly four times the sample. The authors explicitly set out to test Sellon’s result, stating that they expected dewclaw removal to be associated with higher injury risk.

They found no association. Presence or absence of dewclaws was not linked to overall injury risk in their population.

The authors were careful about why the two might differ: their study looked at overall injury risk, while Sellon’s looked specifically at digits. It remains possible that dewclaw removal raises risk for one body region without moving the overall number.

Both studies are owner-reported internet surveys. Neither is strong evidence. That is the honest summary.

A note on breed claims

Dewclaw discussions online frequently single out Labradors, retrievers and other working breeds. There is no Labrador-specific research on this question. The available data comes almost entirely from agility competitors, a population skewed toward Border Collies and similar breeds, doing a very specific kind of high-torque work.

Applying it to a gundog, a street dog or a family pet is an assumption, not a finding.

So what should an owner or breeder actually do?

Strip away the overstatement and a clear, defensible position remains.

Routine cosmetic removal has no demonstrated benefit. It is performed to prevent an injury that the best available data says is the least likely digit injury a dog will suffer. A procedure with no proven upside, performed on a functional digit, should not be the default.

That is a different statement from “removal causes arthritis.” The first is well supported. The second is not, and PNN will not print it as fact.

Medical removal remains entirely legitimate. A badly torn dewclaw, a recurring injury, a tumour — these are real indications, and a veterinarian recommending removal in such a case is on solid ground.

Nail length is the finding nobody talks about. Sellon’s study found long nails carried a higher injury risk than missing dewclaws. Dewclaw nails do not wear down naturally, because the digit rarely contacts the ground at a walk. They curl, they catch, they tear. Trimming them is the single most useful thing in this entire article, and it costs nothing.

The honest conclusion

The front dewclaw is a real digit with real attachments and almost certainly a real function. The campaign to stop amputating it by default was a correction worth making.

But the correction has acquired a confidence the evidence does not support. Two studies have looked. They disagree. Both relied on owners filling in forms.

The case for leaving dewclaws alone does not need the arthritis claim. It stands perfectly well on its own: do not remove a functional body part from a healthy animal without a reason. That argument requires no overstatement, and no veterinarian can dispute it.

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