The shoulder is supported by numerous tendons and ligaments. Tendons attach a muscle to the bone; whereas a ligament attaches one bone to another bone. The supraspinatus muscle is responsible for extension of the shoulder joint. Its tendon attaches onto the front part of the humerus bone of the forelimb.
Cause of supraspinatus tendinopathy
Tendonopathy means “disease of a tendon.” Injury to the supraspinatus tendon usually occurs during hunting or other athletic activities. Extreme and rapid hyperflexion of the shoulder is likely the cause of tear or damage to the supraspinatus tendon. The body’s response to the injury is to lay down calcium deposits within the injured tendon. The calcified material is irritating to the dog and can cause pain and lameness. In some dogs, the calcified tendon does not cause any pain; yet in other dogs it does.
Signs and diagnosis
The most common sign of a supraspinatus tendinopathy is lameness on the affected limb. Sometimes the lameness is subtle, and the owner may only note that the dog is not as powerful on that limb when swimming; thus the dog tends to turn toward the affected limb. Physical examination generally is fairly unremarkable; however, some patients may show signs of pain when the tendon is palpated. X-rays of the shoulder will show a deposit of calcium within the supraspinatus tendon (arrow in X-ray). Blood testing is performed prior to surgery to ensure the patient may safely undergo surgery.
Arthroscopy of the shoulder is frequently recommended to rule out other conditions within the shoulder joint that may be causing lameness. One incision is made over the side of the affected shoulder. The supraspinatus tendon is exposed. An incision is made into the tendon, and the calcified material is removed. After surgery an X-ray is taken to make sure that all calcified material has been removed.
Dogs that receive the surgery usually are able to resume working activities, such as hunting, after complete healing (about 4 months).
For more information on this subject, speak to the veterinarian who is treating your pet.