Biceps tenosynovitis in dogs is the inflammation of the tendon of the biceps brachii muscle and its sheath. This tendon attaches to the scapula (shoulder blades) and crosses over the shoulder joint, and eventually widens to become the biceps muscle. The tendon of the biceps is important in stabilizing the shoulder joint, and the muscle allows for the flexion of the elbow and extension the shoulder. (show diagram of normal shoulder anatomy of biceps tendon)
Biceps tenosynovitis most commonly affects mature medium to large breed dogs, especially Labrador Retrievers and Rottweilers. Because it is caused by repetitive injury to the tendon, biceps tenosynovitis is also seen in athletic dogs, such as agility dogs and racing greyhounds. However, it may also occur less commonly in small breed dogs.
The most common clinical sign in dogs with biceps tenosynovitis is lameness, which can be continuous or intermittent, and is usually made worse by exercise. The dog may experience pain with flexion of the shoulder and extension of the elbow, or just by touching the tendon near the shoulder joint. He/she will still bear weight on the affected limb, but will have a change in gait, since it is painful to not fully flex the shoulder while extending the elbow. As a result, in many cases atrophy (wasting) of the muscles of the affected limb is often present.
Your veterinarian can make an initial diagnosis by taking a thorough history and performing complete physical exam. Radiographs and ultrasound can also be performed but they are not helpful when the condition is in the acute phase. If the damage/injury is chronic, the radiographs can detect mineralization of the tendon and bone spurs surrounding the tendon sheath. A contrast (dye) study can be used to diagnose a tear in the ligament, and your vet may take a sample of the joint fluid to rule out an infectious cause. However, the only way to make a definitive diagnosis is through arthroscopy, which is useful in visualizing the extent of the injury and is minimally invasive.
Biceps tenosynovitis is caused by acute trauma, or chronic repetitive trauma to the tendon, such as extensive jumping activities, or by simple overuse. The condition can also be caused by degenerative conditions such as osteochondritis dessicans (OCD).
In acute cases, biceps tenosynovitis can be managed medically. The goal is to decrease the inflammation, so the patient must be rested and confined, and is often prescribed nonsteroidal anti- inflammatories (NSAIDs). In more chronic cases, injection of corticosteroids into the joint may also be successful, but may have to be repeated. Whether the condition is chronic or acute, the patient must be strictly rested for 4-6 weeks. Physical therapy and weight loss are also beneficial.
For dogs that do not respond to medical treatment, surgery may be warranted. The surgical procdure involves completely cutting the biceps tendon. In some cases, the tendon is reattached to the humerus with a bone screw. Some surgeons do not reattach the tendon. Instead, the tendon is allowed to heal naturally, and gradually adheres to the humerus. In both procedures, normal muscle function is restored with time.
The best method of prevention of biceps tenosynovitis is avoiding overuse of the limb and preventing trauma. Dogs that participate in intense physical activities or agility need to be properly conditioned so the tendon does not strain and become inflamed. As with any orthopedic condition, occurrence of biceps tenosynovitis can be greatly decreased with proper weight management.
Medical management is successful about 50% of the time. Many dogs will need to be treated again, with either another course of NSAIDS or a cortisone injection. Physical therapy may be beneficial in long-term management, and weight control is critical. Many of these dogs will suffer chronic lameness due to the development of arthritis as a result of prolonged inflammation.
With surgical treatment, prognosis is very good, providing the patient with pain relief and resolution of lameness. Full recovery takes about 4-6 months.