Elbow Dyslasia in Dogs

You have a perfectly healthy young dog. All of sudden you notice that your dog has started to limp on one of its front legs. You probably think that it was running too hard yesterday or maybe banged its leg against something. But as the days turn into weeks, the limp doesn’t disappear; in fact it seems to have gotten worse. It’s beginning to interfere with your dog’s daily exercise. You decide to bring your dog to the veterinarian and they tell you that your dog has ‘elbow dysplasia’.

There are three conditions that are commonly diagnosed in dog elbows- osteochondritis dissecans, un-united anconeal process, and fragmented coronoid process. These terms may sound confusing, but this article will attempt to give you a basic concept about elbow problems (‘elbow dysplasia’) in young dogs.

Every joint in a dog’s body is a junction of the ends of bones, covered by cartilage and lubricated by fluid to allow smooth movement. The elbow joint is composed of three bones. The humerus is the bone that runs between the shoulder and elbow joints. The other two bones that meet the humerus to form the elbow joint are the radius and ulna. The radius is the bigger bone that bears most of the weight when the dog walks. The ulna runs behind the radius, and is an odd shape. At the level of the elbow joint, it has two ‘arms’ that hug partway around the top of the radius. The ulna also comes to a point, forming that bony point that you tend to rest on desks and tables.

It all starts with osteochondrosis. This is a problem that can affect many different joints, including the elbow. It happens when some of the bone near the joint does not mature properly. In this case, a big piece of cartilage is left where there should be bone. It is believed that the three most common elbow conditions are associated with osteochondrosis.

Osteochondritis dissecans (OCD) occurs in the same areas where osteochondrosis commonly affects the elbow joint. In OCD, the cartilage core completely or partially breaks off of the joint surface and hangs freely in the joint fluid. This flap eventually becomes mineralized and can be seen in the joint space on x-rays. This is called a ‘joint mouse’. The treatment for OCD is the surgical removal of the joint mouse. Most dogs improve after surgery but many continue to have mild joint problems requiring anti-inflammatory drug use throughout life.

Un-united anconeal process (UAP) occurs when the ulna fails to fuse properly. The bony point of the ulna is called the anconeal process, and can cause elbow pain and joint disease if it does not properly fuse to the rest of the ulna. Fusion normally occurs at five months of age, so this condition can not be diagnosed until a dog is over five months old. The treatments of choice are either surgical re-attachment or removal, depending on the severity of joint damage. Like OCD, dogs treated for UAP often have mild joint problems and arthritis throughout life.

Fragmented coronoid process (FCP) is damage to one of the ‘arms’ of the ulna that wrap around the top of the radius. Dogs with this condition often also suffer from OCD. Treatment is controversial; there is a surgical option for the removal of the bony pieces. However, no definitive treatment is available and the prognosis for dogs with FCP is similar to the other two conditions.

OCD, UAP, and FCP are the three conditions that are lumped together in the term ‘elbow dysplasia’. All three problems have similar stories; they all occur in young (6 months to a year of age), fast-growing, large-breed dogs. Males are more commonly affected than females. It is not unusual for any of these conditions to be found in both elbows.

Elbow dysplasia is sometimes difficult to diagnose. Signs of elbow pain can be vague and misinterpreted as shoulder pain. Even though these diseases are diagnosed by taking x-rays, changes seen early in the course of disease can often be very mild and difficult to identify on x-rays.

Joint disease in young, growing animals is frustrating because we don’t expect our animals to develop arthritis so young. However, with proper veterinary care, elbow dysplasia can be perfectly manageable. Your dog may not be able to become involved in high levels of athletic competition, but will certainly be able to live a comfortable life. If you have any questions about elbow dysplasia, contact your local veterinarian.

By Ashley O’Driscoll – Pets.ca writer