Angular Limb Deformities in Dogs: Types, Causes & Treatment

Angular limb deformities in dogs are deformities that affect the bones. Carpal valgus in dogs is an outward turning of the paw from the level of the wrist and is a frequently encountered example of an angular limb deformity. In all cases, angular limb deformities result from atypical bone growth due to rapid growth or damage or injury to a dog's bony growth plate. Let's take a closer look at what this might mean for your dog.

Causes of Angular Limb Deformities

All dogs' lower front legs have two long bones between their elbow and their wrist: the radius and ulna. Traumatic injuries, such as sustaining a car injury, falling or being stepped on are common causes of trauma that can result in angular limb deformities in dogs. Exactly how does this occur? Injury to a growth plate can alter and cease further growth of that bone. Due to its unique anatomy, the ulna's growth plates are at high risk for injury. Any such injury can cause the ulna to stop growing, but the radius will continue to grow. Because the two bones are connected by ligaments, the radius is under pressure and forced to alter its angle, as it's anchored down to the ulna. This gives the limb an abnormal twisted or bowed appearance.

Other causes of angular deformities include eating a food that is poorly balanced for calcium and phosphorus or excess calories and minerals fed to puppies. This is especially problematic in the fast growing, large and giant breeds of dogs. In these cases the rapid growth of the bone coupled with imbalanced or excess dietary minerals

Types of Angular Limb Deformities: Carpal Varus and Carpal Valgus in Dogs

According to veterinary specialist, Dr. Derek Fox, DVM, Ph.D., DACVS, there are numerous types and categories of angular limb deformities in dogs. In DVM360, Dr. Fox reports that classification is based on how many deformities a dog has, the direction of the bony deformities and how the bony deformities relate to one another.

Two commonly encountered types include:

• Carpal varus: In carpal varus of the foreleg, the elbows buckle or bow out more than the feet and other parts of the limb, and the feet may point inward.
• Carpal valgus: Carpal valgus in dogs occurs when the front feet point outward, or deviate away from the limb and the body's alignment.

Swelling at the elbow joint, along with pain, may be present with either type of deformity.

If this sounds like a rather complicated classification scheme, you aren't wrong. Even for veterinary professionals, this can be confusing to keep straight. The good news is you don't need to master it; simply be aware that most of these deformities affect a dog's lower front limb. You can leave the rest to your veterinarian.

Clinical Signs and Diagnosis

Angular limb deformities in dogs affect both large and small breeds, and they're most often observed when a dog is less than one year old. According to the chapter devoted to angular limb deformities in "Mechanisms of Disease in Small Animal Surgery" certain dog breeds, such as bulldogs or dachshunds, already have shortened legs, but these aren't considered angular limb deformities. Their short legs are part of their normal breed shape; they're symmetrical and they don't usually cause mobility problems. However, even these breeds can develop an angular limb deformity from the same causes as other breeds. Unusual twisting or angles of the limb are the telltale signs; lameness is another key indicator of this bony deformity.

Your vet will diagnose an angular limb deformity based on orthopedic exam findings and radiographs of the affected forelimb. They'll likely take an X-ray, sometimes with the dog under sedation, of the affected limb. This allows your vet to develop a precise surgical plan to correct the deformities.