In the normal growth process of bones, cartilage should calcify and help to form solid bones. If the cartilage fails to be replaced by bone cells, it becomes abnormally thickened and unable to receive nutrients into all its cells, which can lead to malnourishment and cell death. This dying tissue can then become detached from the bone due to normal weight bearing, and form a flap that can reattach or break completely free.

Once this occurs, the condition is usually referred to as osteochondritis dissecans. Flaps that break free are called joint mice, and can be reabsorbed by the body or can remain in the joint and mineralize, causing further pain.

Shoulder dysplasia refers to a condition that typically affects large and giant breed puppies. Due to a defect in the normal growth process, the cartilage of the shoulder pulls away from the bone, resulting in pain and inflammation. If left untreated, the condition can lead to lameness in the affected limb. Often, the condition will affect both shoulders.

Signs of a condition of shoulder dysplasia are usually evident between 4 to 10 months of age, and may be subtle. Even if your dog has shoulder dysplasia in both shoulders, usually only one is painful. Pain and shifts in weight can lead to a lameness that lessons with rest, but can become exacerbated with exercise. The lameness generally increases within a period of 3 to 4 weeks. Symptoms can include:

The cause of shoulder dysplasia has not yet been discovered, but there are many factors that are believed to contribute to this condition. Factors include:

Large and giant breeds seem to be predisposed to this condition by their very nature of increased weight bearing and rapid periods of growth, though shoulder dysplasia can affect smaller and medium dogs as well. Common breeds affected include:

Once you have noticed your dog limping, having pain, or going through periods of lameness, you should take your dog in to be checked. Your veterinarian will perform a physical exam, and a lameness exam, and will note areas of pain, inflammation, and atrophy. Your dog’s shoulder may be warm and swollen to the touch, and he may cry out when the joint is manipulated. A click may also be heard when the shoulder is hyperextended, an indication of a degenerative issue in the joint. At this point, your vet will most likely order imaging tests to better assess the problem.

X-rays, CT scans, and MRIs can reveal the state of the shoulder joint, and may be performed on both shoulders even if only one is painful. These techniques can reveal abnormal fluid or space in the joint, joint mice, and the presence of osteoarthritis. Shoulder arthrography may be helpful in discerning defects in the joint that are not seen in imaging techniques alone and involves a small incision in the shoulder joint to allow a camera to look inside. A definitive diagnosis of shoulder dysplasia is based on the results of these tests.

Treatment of your dog’s shoulder dysplasia will depend on the severity of the condition, and is generally divided into non-surgical and surgical methods. 

More conservative methods of therapy are usually indicated for dogs with mild dysplasia that is accompanied by little to no pain. Restricting your dog’s exercise through strict rest and short leash walks can help the flap of cartilage heal on its own. This can be accompanied by range of motion exercises to maintain the joint’s flexibility. Often, the diet is modified to manage body weight, or to decrease the intake of calcium or calories, and supplements to aid in joint health may be added. Medications are often prescribed to help manage pain and inflammation, such as NSAIDS and steroidal or non-steroidal anti-inflammatories. Newer treatments include laser therapy and the administration of platelet rich plasma.

Some dogs will see improvement in their symptoms, but may need some physical therapy. Other dogs may only experience temporary pain relief, and may progress to osteoarthritis and permanent lameness. When the condition does not improve with non-surgical methods, surgery may be needed. Many of these conservative methods can also be used after surgery to aid in recovery.

Surgery is recommended in more severe cases, such as when the cartilage breaks free of the bone and joint mice are present, and if the dog is over 8 months of age. Surgical procedures performed before that time may hasten the disease. Surgery aims to repair the cartilage by removing the cartilage flap from the joint and scraping away any defective cartilage tissue. This can relieve pain and inflammation, as well stimulate joint healing. Treatment is performed through an open surgical approach or through arthroscopic surgery, which is a minimally invasive method that lessens the disruption to internal tissues and decreases post-operative pain. 

Surgical treatments, along with postoperative supportive methods, are the therapy of choice for most owners and veterinarians as they can provide a 90% success rate with a full recovery. Removal of the defective cartilage also decreases the onset of degenerative joint diseases common with this type of joint dysfunction.

During treatment or after surgery, your dog’s activity should be limited, and you may be given medications, a special diet, and joint supplements to administer to your dog in the following weeks of recovery. Your veterinarian will instruct you on types of exercises or activities that you can gradually begin to do with your dog after a period of time. 

Recovery with non-surgical methods is variable, and depends on the severity of the condition. Very mildly affected dogs can recover under these therapies, but more often, the symptoms return. Surgical methods carry an excellent rate of recovery, especially if they are performed before the disease progresses too far.

While there is still debate as to the cause of shoulder dysplasia, prevention may be possible with an appropriate diet that limits the intake of energy and calcium, as well as refraining from breeding affected dogs.