If you’ve adopted a puppy or young dog that’s still growing, you may be assuming you don’t need to worry about his bone health for years to come. But the fact is, growing pups are susceptible to specific bone problems, such as angular limb deformities. These are bone growth issues that cause limbs to develop in a curved or crooked direction rather than straight.
• Angular limb deformities occur in young, developing animals as a result of trauma to the growth plate in the leg. Often, the trauma is caused when a puppy is hit by a car, stepped on, dropped or injured in some other way.
• An angular limb deformity also sometimes results from the growth plates closing prematurely. Certain breeds, such as the basset hound, shih tzu and dachshund, are genetically predisposed to premature growth plate closure. Many of these dogs have short, slightly crooked legs. While this leg development is technically normal for some of these breeds, the problem is sometimes so pronounced it can cause lameness.
How can injury cause deformity?
Most of your dog’s growth occurs between four and eight months of age. During this time, his bones grow and lengthen – a process made possible by the growth plates at the ends of long limb bones. When a puppy reaches about one year of age, the growth plates close. After this point, an injury to the leg won’t result in the overwhelming damage or deformity seen in puppies.
If an immature growth plate – which is often softer than other parts of the bone – gets injured, the damaged cells stop growing. Meanwhile, the uninjured cells continue to grow. Since growth plate injuries typically occur on one side of the plate or the other, the damaged side of the bone quits growing, but the healthy side continues to grow. This is how the bone ends up anything but straight.
The most common angular limb deformity occurs in a puppy’s forearm, which has a two-bone system comprised of the ulna and the radius. If the growth plate of either of these bones is injured (usually it’s the ulna), the damaged bone will stop growing, but the other bone in the two-bone system will continue to grow. The damaged, no-longer-growing bone acts like a rubber band, putting tension on the growing bone. This causes the healthy bone to bow, curve or rotate as it continues to develop. In some worst case scenarios, the bone can develop all three deformities – it can bow, curve and rotate.
Younger dogs whose bones are still growing – especially large and giant breed puppies – are at much greater risk for developing a severe deformity after a traumatic injury than older animals are. If the problem isn’t diagnosed quickly and corrected with surgery, there can be much bigger problems in the future for the injured puppy. Limb deformities result in abnormal joint movement, which can be quite painful for the dog. Arthritis is another common outcome, along with the inability to move normally. If the deformity is severe and left untreated, a dog can actually lose all function in the affected limb.
Early diagnosis is crucial
If you have a young, growing puppy, and know she’s been injured, it’s important to get her seen by your veterinarian right away. Early diagnosis of traumatic bone injuries is essential if your pup is to have a good treatment outcome.
Crushing injuries that damage the cells of the growth plate aren’t picked up on x-rays. In addition, it can take a few weeks after your puppy is injured for an angular limb deformity to start to become obvious. It’s extremely important to know if your dog has sustained an injury, and you also need to continuously compare the length and straightness of a potentially damaged leg to the uninjured leg. If you detect any developing differences between the two legs, seek immediate veterinary care.
Treatment means surgery In some cases, surgery is necessary to make every effort to straighten the damaged bone. In severe cases, multiple surgeries will often be required. The type of surgery will depend on the injury, which bone is damaged, your dog’s age, and how much growing she still has left to do.
Two primary types of procedure are performed to correct angular limb deformities.
1. For young dogs with forelimb damage and plenty of growing left to do, the ulna (which is usually the injured bone) will often be cut and detached from the radius. This allows the radius to straighten and the limb to grow normally.
2. In older pups that are at, or very close to, their full adult size, a form of corrective surgery called an osteotomy is often performed. This involves cutting both the ulna and radius at the point of greatest curvature. The radius is then straightened, which allows for proper alignment of the elbow and wrist joints.
Corrective surgery requires about four to six weeks for healing. During this period, it’s really important your dog remains strictly confined in order to limit mobility. This will ensure efficient healing and the best outcome postsurgery. Some dogs will require a second surgery, called a limb-lengthening procedure, in addition to surgery for straightening the leg.
Ensuring your pup matures into a healthy dog with straight bones means keeping bone problems from developing in the first place. Angular limb deformities sound scary, but by taking a few simple preventive steps while your dog is still growing, you won’t have to worry about them.