The shoulder joint is a "ball-and-socket" joint. It is made up of the scapula (shoulder blade), and the humerus (front leg) as well as associated muscles, ligaments and tendons. A ligament is a band of connective or fibrous tissue that connects two bones at a point while the tendon is a band of connective or fibrous tissue that connects a muscle to a joint.
Lameness in dogs is mostly due to shoulder-joint ligament and tendon conditions. Medium and large breed dogs are prone to this condition during the ages of one to seven years.
Biceps tenosynovitis is inflammation of the tendon of the biceps muscle and its sheath. The causes of this problem are repeated injury to the biceps tendon, acute severe trauma, and chronic osteochondritis dissecans of the shoulder joint.
Symptoms depend on severity of the condition.
A decrease in muscle mass is a consistent finding for all conditions
Bicipital tenosynovitis (an inflammation of the tendon and surrounding sheath of the biceps tendon – at the front of the shoulder blade)
Onset is usually subtle
Often of several months’ duration
Trauma to the limb or shoulder may be the inciting cause
Subtle, intermittent lameness that worsens with exercise
Short and limited swing-phase of gait owing to pain on extension and flexion of the shoulder
Pain inconsistently demonstrated on manipulation of shoulder
Rupture of the tendon of the biceps brachii muscle (upper limb)
Signs similar to bicipital tenosynovitis
May have sudden (acute) onset due to a known traumatic event
Usually subtle, long-term (chronic) lameness that worsens with exercise
Mineralization of the tendon of the supraspinatus (shoulder joint) muscle — onset is
usually subtle
Long-term (chronic) lameness that worsens with activity
-Forcible separation (known as an avulsion) or fracture of the tendon of the
supraspinatus muscle (tendon that connects the scapula/bone of the shoulder blade
with the humerus/bone of the upper limb)
-Signs are similar to mineralization of the supraspinatus tendon.
-Deterioration and scarring (known as fibrotic contracture) of the shoulder muscle —
usually sudden (acute) onset, occurring during a period of intense outdoor exercise
(such as hunting).
-Shoulder lameness and tenderness gradually disappears within two weeks
-Left untreated, condition results in long-term (chronic), persistent lameness, usually
taking place 3 to 4 weeks later; may not be particularly painful to the dog
-Decrease in muscle mass of the infraspinatus muscle (muscle atrophy)
-When patient is walking, lower limb swings in an arc away from the body, as the paw is
advanced
