A bursa is a closed sac lined by a membrane that secretes a lubricating fluid. These sacs are located at strategic points between moving parts and act as cushions to prevent friction and chafing. Bursitis can range from a mild condition to one which becomes septic--the presence of infection. Trauma to a bursa--either a direct blow or the mechanical stress of racing--produces a painful swelling called acute bursitis. Acute bursitis causes lameness. There are several common locations, which are affected by acute bursitis.
Bicipital or shoulder joint bursitis follows a kick or a blow to the point of the shoulder. Signs are swelling and a noticeable limp. X-rays are advisable to rule out an associated fracture. With shoulder joint lameness, a horse in motion will often swing his leg out wide in a half-circle.
Treatment for bicipital bursitis includes rest until the signs of lameness are gone. Anti-inflammatory drugs such as flunixin melamine (Banamine) or phenylbutazone (Butazolidin) help relieve pain and swelling. Injections of cortisone into the bursa are often beneficial.
Trochanteric bursitis, sometimes called Whorlbone lameness, is a painful hip lameness caused by inflammation of a bursa beneath the tendon that crosses the head of the femur. It is the result of tendon overuse that occurs during racing or hard training. It is seen most often in standardbred racehorses. A horse with trochanteric bursitis carries the foot inward and puts most of his weight on the inside edge of the foot.
Injecting the bursa with corticosteroids is often an effective treatment. As an alternative, the bursa can be injected with an obliterating agent such as Lugol's iodine solution. Phenylbutazone (Butazolidin) is given to relieve pain and swelling.
Cunean Tendon Bursitis
Cunean tendon bursitis is a painful inflammation of the bursa beneath the cunean tendon at the inside of the hock joint. The condition is common among harness racers. In fact, it is said that most standardbred horses will be affected at some point in their racing careers.
Acute bursitis results from a shearing stress produced as the foot impacts and pushes off during extended fast pacing or trotting. Improper shoeing and incorrect conformation are believed to contribute. In the majority of cases, there is an associated bursitis of the small tarsal bone within the hock joint, causing some experts to refer to the condition as a cunean tendon bursitis-tarsitis. Characteristically, the horse exhibits a "Cold lameness"; that is, the lameness diminishes or disappears as the horse warms up. With continued abuse, the lameness becomes constant, with the horse putting as little weight as possible on the affected leg and moving in shorter steps while carrying the leg to the inside. According to Dr. Thomas Gore, DVM, the lameness is reversible with the proper treatment, which involves corrective shoeing, slower workouts at longer distances, phenylbutazone (Butazolidin), and a corticosteroid and/or hyaluronic acid injection into the tarsal joints.
Calcaneal bursitis, referred to as capped hock, is a boggy swelling over the point of the hock caused by single or repeated trauma, such as kicking a wall or trailer gate. By itself, it is not a cause of lameness. Treatment for capped hock generally involves draining the area and the use of corticosteroids or an iodine solution.
Olecranon bursitis, known as capped elbow, is similar to calcaneal bursitis. It is a soft, boggy swelling of the bursa that overlies the point of the elbow. It occurs in horses who bang the elbow when getting up and down on hard surfaces. A shoe hitting the elbow when the horse is recumbent can also cause it. It usually does not cause lameness. Treatment involves the bursa being drained and injected with a corticosteroid or an iodine solution. This may have to be done several times. Alternatively, the bursa can be opened and packed with gauze containing Lugol's iodine solution, or a drain can be left in place until the cavity obliterates. If these procedures are not successful, the bursa can be surgically removed.