Overview of Canine Angular Limb Deformities
An angular limb deformity is an abnormally shaped or crooked limb that results from abnormal growth of the bones. Angular limb deformities are most commonly seen in the forearm (radius/ulna), but can also be seen in the lower part of the hind leg (tibia/fibula).
Injury to young, growing bones can result in an angular limb deformity. These injuries can include being hit by a car, stepped on, dropped or getting a limb caught in the doorway. Abnormally shaped bones then put abnormal forces on the joints, which can lead to pain and arthritis.
Diagnosis of Angular Limb Deformities in Dogs
Your veterinarian will ask you many questions to develop a complete history of the progression of the problem. These questions will include:
Your veterinarian will also examine your pet completely, including checking for a fever, listening to his heart and lungs, palpating your pet’s legs, checking for pain, checking the mobility of the joints and checking symmetry between the legs.
X-rays are usually taken of the affected leg and the opposite leg to compare the affected side with the normal side. If it is a recent injury, there might not be obvious X-ray findings early on. These initial X-rays should be used as a baseline to compare to future X-rays.
Treatment of Angular Limb Deformities in Dogs
Early diagnosis and treatment is essential for the best chance for a successful outcome.
Surgery is often necessary to straighten bones affected by an angular limb deformity. The type of surgery performed depends on the individual injury, the bone(s) affected and the patient’s age and growth potential. Often, the abnormality in the limb is severe enough to warrant more than one surgery to repair it.
After corrective surgery, the dog should have rest and restriction from activity for about 4 to 8 weeks to allow the bones to heal. Frequent re-check examinations by your surgeon are necessary to identify potential problems and correct them as soon as possible.
Re-check X-rays are necessary to monitor the progress and assess the success of the corrective surgery. They are also important to see if the bone, which is often cut during the corrective surgery, has healed enough to allow unrestricted activity.
If your pet licks or chews at his incision, an Elizabethan collar may be necessary to keep him from opening or infecting the incision. If a bandage, splint or cast has been placed on the limb, it is important to keep the pet from chewing at it, and to keep the bandage clean and dry. A wet bandage or one that has been chewed up must be replaced as soon as possible. A chewed bandage loses most of its supportive qualities.
Follow your veterinarian’s instructions closely to get the best results. If you own a young, growing dog and he becomes injured, have your veterinarian examine him. Compare the length and straightness of the unaffected and affected leg, and contact your veterinarian as soon as possible if you notice a difference.
In-depth Information on Angular Limb Deformities in Dogs
An angular limb deformity is an abnormally shaped, curved, or crooked limb. Angular limb deformities occur in young, growing animals after a traumatic event, such as being hit by a car, getting stepped on or dropped.
Bones grow lengthwise by elongation and multiplication of the cells at the growth plates or physes. There is a growth plate on each end of the bone.
Angular limb deformities most often occur in the forearm (radius/ulna), but can also occur in the lower hind limb (tibia/fibula). An injury to the growth plate causes crushing of the growing cells and stops their growth (premature closure of the physis). This type of crushing injury to the cells is not apparent on X-rays.
The crushed cells stop growing, while unaffected cells continue to grow. Often the damaged portion is on one side of the bone, causing one side to stop growing while the other side continues to grow. This makes the bone grow in a curved shape, similar to a plant that curves toward sunlight.
The forearm consists of a two-bone system: the radius and the ulna. If the growth plate in one of these bones is damaged, then that bone will stop growing. The other bone will continue to grow and is tethered by the damaged bone, causing a curvature or bowstring effect. Most often, the ulna is damaged after an injury to the forelimb because the shape of the physis is cone-shaped and can be injured in many different directions.
Unequal lengthening of the bones can also cause abnormal joint contact, or joint incongruity. This can result in pain, arthritis or abnormal mobility.
It can take a few weeks after an injury for an angular limb deformity to become apparent, depending on the growth rate of the pet. Some breeds are predisposed to premature closure of the growth plates, causing abnormally short, crooked legs. This is normal in breeds such as the basset hound, shih tzu and dachshund, but sometimes this “normal” abnormality is more pronounced than expected and causes lameness.