A dog with angular limb deformity (ALD) has a leg — or legs — that grow in bowed or twisted.
For some breeds, such as bulldogs, dachshunds, and shih tzus, bendy legs are considered normal, even if, anatomically, their bones are distorted compared to other breeds, such as Labradors. These dogs have been selectively bred to produce angled limbs, and their condition is a result of genetics.
ALD can also be the result of injury to the growing bone, which has caused the delicate growth plate to stop working.
Regardless of the cause, ALD interferes with a dog’s ability to walk and run as nature intended. Bowed, twisted or rotated bones place abnormal forces on muscles and joints, resulting in mechanical lameness (the leg cannot physically move as it should) and extra strain on joints, leading to sprains and early arthritis.
As a puppy with an injured growth plate grows up, his legs no longer look symmetrical. The damaged leg appears bowed or bent compared to the opposite side.
It can be difficult to spot the difference between the two early on, so if in doubt, take photos of your puppy’s legs on monthly and compare the shots. If the problem needs surgical correction, the earlier it is spotted, the better the outcome for the dog.
If your dog was bred to have ALD and his deformity is causing a problem, the signs are lameness and difficulty walking.
ALD happens because of a difference in the rate of growth of two bones lying side by side.
In the foreleg, this is the radius and ulna, and in the hind leg, the tibia and fibula. These bones are meant to lengthen at the same rate and be equally matched.
With ALD, one bone grows slowly, thus restricting the growth of its neighbor. This is called the bowstring effect, because it is like tightening the string of a bow, causing it to arch and bend.
The majority of bone growth takes place when the pup is 4–8 months of age. Growth plates at either end of the long bones create new bone. An injury to the growth plate, such as treading on the leg or a traffic accident, can cause the growth plate to scar over and stop growing.
All dogs from certain breeds have ALD, but for dogs that acquire ALD through injury, the trick is to identify exactly why the bone is no longer growing normally.
Radiographs are of some help, but the gold standard is a CT scan. In the hands of an orthopedic specialist, this provides invaluable information about where the seat of damage is and allows the surgeon to plan the best corrective surgery.
The best chance of returning a limb to normal is early corrective surgery. With this aim in mind, seek expert advice as soon as you suspect a problem.
Specialist orthopedic surgeons assess how to best correct the problem.
The options include:
- Cutting the too-short bone so it stops holding back the longer bone, allowing it to spring back into a proper shape
- Correct abnormal rotation of a bone, but cutting and realigning it without the twist; the bone is then held in the position with bone plates
- In very young dogs, a portion of the too-short bone may be completely removed so it no longer holds back the growth of the partner bone
- If both growth plates closed too early, an external fixator device may be fitted with adjustable sliders to allow the bones to be “stretched” a little every day
Large-breed puppies are vulnerable to growth plate damage during rough play or if exercised excessively while their soft growth plates are developing. To this end, it is wise not to over-tire the puppy.
Also, chose an appropriate diet for the nutritional requirements of large-breed bone growth — plenty are available and are marketed as “large-breed growth.”
- “T-Plate fixation of distal radial closing wedge osteotomies for treatment of angular limb deformities in 18 dogs.” Balfour, Boudrieau & Gores. Veterinary Surgery, 29(3): 207–217.
- “Initial clinical experience with the IMEX circular external skeletal fixation system: Use in bone lengthening and correction of angular and rotational deformities.” Lewis, Radasch et al. Vet & Comparative Orthopeadics and Traumatology. Issue 3, 1999: 23–32.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 1, 2015.