There are several types of angular limb deformities seen in dogs, usually identified when they are puppies. A canine angular limb deformity means the bones, usually of the front legs, do not grow as straight as they are expected to. In the lower front leg, the radius and ulna are the two parallel bones. If they do not grow at the same rate due to damage to a growth plate, the leg will begin to bow either inward or outward. In dachshunds, the tibia, the lower bone in the rear leg, can be affected.
What Causes Angular Limb Deformity in Dogs
The causes of angular limb deformities in dogs include trauma and genetic or congenital factors. The bowing of the leg due to the deformity is likely to lead to joint damage if the disorder is not recognized and corrected promptly.
The most commonly affected dog breeds are chondrodystrophic breeds. In other words, breeds with short limbs such as Pembroke and Cardigan Welsh corgis, Shih-tzu, dachshunds and basset hounds. But these deformities can also affect Shetland sheepdogs, collies, Newfoundlands and Rottweilers.
Additional Causes of Canine Angular Limb Deformity
Badly healed fractures can also cause angular limb defects. Any time there is a fracture or trauma to a growth plate, or other evidence the foot is beginning to deviate inward or outward, prompt veterinary intervention is essential to minimize damage and arthritis.
In many cases, angular limb deformities in dogs are caused by trauma to the growth plate of the ulna, the longer bone in the lower front leg. This trauma causes the growth plate to close in the ulna before the growth plate in the radius, the parallel bone, closes. This means the ulna stops growing while the radius continues to grow. This causes the foot to begin to deviate outward, a valgus deformity. This can also be caused by a genetic or congenital defect, causing one or both growth plates to close prematurely.
This growth plate closure secondarily causes a malalignment of the elbow, called elbow incongruency. There is associated lameness; if this is not corrected with surgical intervention, will lead to significant elbow arthritis as the dog ages. In most cases, this specialized surgery should be performed by a surgical specialist, a board-certified surgeon.
Varus and Valgus Deformity in Dogs
A deformity where the foot rotates outward is called a valgus deformity. When the deformity rotates the foot inward, it is called a varus deformity. Symptoms include a change in the direction of the foot, a shortening of the leg, lameness, pain, swelling, and/or decreased range of motion of the affected joint(s).
This deformity can occur in one leg or in matching sets of legs, meaning both front legs or both back legs. Trauma is likely to affect one leg. Genetic or nutritional problems are likely to affect matching left and right legs. X-rays are critical in assessing for trauma, damage, and joint involvement. Quality X-rays including the elbows are essential.
How to Help a Puppy With Angular Limb Deformity?
Early intervention is critical for a good outcome, particularly if the puppy has a significant amount of growth yet to achieve. If there is lameness, intervention is more important. Some patients will respond to nutritional adjustments. Too much protein and fat in the diet or adding calcium and/or phosphorus can contribute to angular limb deformities in dogs. In general, if the puppies are put on a less calorie dense food with lower amounts of calcium and phosphorus such as an adult dog food, they will slow down and straighten out. Most veterinarians do not recommend vitamin C, also EsterC as it acidifies the system and does not help with these deformities.
All dogs who appear to be developing these canine angular limb deformities require close monitoring. Surgical intervention may be required if nutritional adjustments do not lead to a resolution.
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Written by: Marty Greer, DVM
Director of Veterinary Services
Marty Greer, Doctor of Veterinary Medicine, has 40+ years’ experience in veterinary medicine, with special interests in canine reproduction and pediatrics. She received her Doctor of Veterinary Medicine from Iowa State University in 1981. She’s served as Revival’s Director of Veterinary Services since 2019. In 2023, Dr. Greer was named the Westminster Kennel Club Veterinarian of the Year.