If a dog has extra toes on its rear feet that are right alongside the regular toes, are they dewclaws?
Probably not. Extra toes, or polydactyly, occur occasionally in dogs though it’s more common in cats. The most frequently seen cases in dogs involve rear and/or extra dewclaws which do not touch the ground when the dog is standing normally. Dogs will sometimes have polydactyly involving other toes.
There is an example of polydactyly in Aussies. In the 1980s an X-chromosome linked genetic disease that caused multiple skeletal anomalies was identified. Females with a copy of the mutation had extra or fused toes. Most of the references to polydactyly in Aussies you will find in scientific literature relate to these dogs, all members of a single family.
What are dewclaws?
Dewclaws are fifth toes on either front or rear legs. They emerge along the side of the lower leg and do not touch the ground when the dog is in a normal stance.
Why are front dewclaws important?
They are equivalent to our thumbs. Even though these toes don’t reach the ground when a dog is standing or trotting, they are functional, stabilizing the carpal (wrist) joint, especially when moving at speed or making sharp turns. They are used for self-grooming and to help steady objects a dog may hold between its forepaws when lying down. All but one wild dog species (the African Wild Dog or Painted Wolf) have front dewclaws, including all those most closely related to domestic dogs.
Removing front dewclaws can impact health: Physically active dogs which have had the front dewclaws removed are prone to developing arthritis at the carpal joint, sometimes sufficiently severe and early to end a performance event or working career
Can a dog have multiple dewclaws on one leg?
Yes. Double rear dewclaws are required in some breeds. Sometimes a dog may have triple rear dewclaws. Multiple front dewclaws are abnormal. Rear dewclaws are abnormal for members of the dog family in general (wolves, foxes, etc.), but do occur in domestic dogs. Whether they are “normal’ or not depends on the breed. They are not normal in Aussies and should be removed.
Why should rear dewclaws be removed?
Front dewclaws are allowed to be removed per the breed standards, but shouldn’t be for functional reasons. There is some evidence that active working or performance dogs without front dewclaws are more prone to certain types of injury. Rear dewclaws, however, are remnants of the first toe which most members of the dog family lack on their hind legs. They are non-functional and should be removed in breeds where they aren’t required (including Aussies.) Rear dewclaws almost never have skeletal attachment to the other bones in the rear legs. They are encased in flaps of skin that protrude from the leg and lack continuity with the remainder of the skeleton. In field conditions they may snag on things and tear.
How common are rear dewclaws in Aussies?
There are no statistics on rear dewclaws, but they don’t appear common. However, they obviously occur often enough – or at least did historically – for them to merit mention in the breed standards.
How are rear dewclaws inherited?
Unknown, but since they are characteristic of some breeds, they are inherited.
How should I handle rear dewclaws in my breeding program?
They should be considered faulty and bred away from.