Chronic injury and poor performance in sporting dogs with forelimb injuries (Proceedings)

Retrievers and gundogs often work in conditions of uneven terrain, with poor visibility and extreme ambient temperatures. In this sport, shoulder injuries are the most common serious injury sustained. Strain and sprain of the biceps, lateral and medial glenohumeral ligaments were cited as causes, however advanced diagnostics were not used to determine the cause of the shoulder lameness. Agility dogs commonly injure their shoulder as well, presumably due to high intensity repeated impact of the joint and surrounds tendons on obstacles such as the A frame.

Bicipital tenosynovitis is usually a chronic injury of the forelimb that develops over time as the tendon tears slowly and then subsequently develops dystrophic mineralization. On examination pain will be elicited on palpation of the tendon and flexion of the shoulder joint. For some cases, conservative management will resolve the problem and includes rest with one injection of corticosteroids into the shoulder joint, which is confluent with the tendon bursa.

Rehabilitation often includes therapeutic ultrasound; passive range of motion exercises, strengthening exercises and underwater treadmill therapy. With surgical treatment, the tendon is released arthroscopically and may or may not be fixed to the proximal humerus. I perform fixation in these cases with a lag screw and washer if the dog's owner is planning to return the dog to sporting activities. I recommend rehabilitation postoperatively for these dogs, in order to develop the brachialis muscle, which can function for flexion of the elbow and take the pressure off of the biceps brachii muscle.

Osteochondritis dissecans (OCD) of the shoulder occurs at the caudal humeral head and is a common cause of lameness in dogs 4 to 10 months of age. It is more common in large breed males and can be unilateral or bilateral. Early cases may not have radiographic signs of a collapsed/flattened caudal humeral head or a cartilage fragment but there is pain on flexion of the shoulder. If radiographs are unremarkable, nuclear scintigraphy, computed tomography or arthroscopy can be performed to obtain a diagnosis.

Treatment is to surgically remove the cartilage flap and debride the subchondral bone, most often this is done arthroscopically and the prognosis is fair to excellent. Because up to 80% of cases are bilateral, both shoulders should undergo diagnostic testing. Nonsurgical management is not recommended but may be attempted by strict rest but resolution of lameness may not occur for 7 months and osteoarthritis (OA) may develop long term. Dogs with OCD of the shoulder may compete following recovery from surgery but are more likely to develop a chronic lameness earlier in their career with the development of OA, especially in sports where shoulder injuries are common such as agility and gundog sports.

Supraspinatus insertionopathy involves the supraspinatus tendon becoming torn or strained over time. This chronic injury does not result in any lameness until there is ossification of the tendon and impingement on the biceps tendon. On exam you will see pain on flexion of the shoulder and may get biceps tendon pain as well. Calcification of the tendon can be present and never cause any clinical signs. The decision to treat should be based on clinical presentation of the dog which includes lameness with exercise or following rest. Treatment can be aimed at surgical removal of the ossified body, however recurrence is common.

Extracorporeal shock wave therapy can be used to resolve the condition along with underwater treadmill therapy and exercises to restore shoulder function and resolve pain associated with the condition. A tendonopathy of the supraspinatus muscle does not have calcification present but there is chronic pain present on flexion of the shoulder and palpation of the tendon. An MRI is needed to identify this soft tissue injury or arthroscopy can sometimes be used to see the tendon abnormality. Most cases can be treated conservatively with rehabilitation, and may include laser therapy and underwater treadmill exercises.  

Labrador retrievers may develop tendon and bursal ossification of the infraspinatous muscle. There may be no clinical signs or pain may be present on palpation of the tendon. Some dogs respond to conservative management with rest and corticosteroid injection into the bursa while others require surgical resection of the mineralizations. As many as 50% may not fully recover from the condition. On arthroscopy, one can see pathology in other shoulder structures such as the medial glenohumeral ligament or biceps tendon and these may be contributing to the presenting clinical signs.

Infraspinatous contracture occurs in hunting dogs and may be the result of trauma. The dog has a lameness and swinging gait since it cannot adduct the limb and there is atrophy of the muscle caudal to the spine of the scapula. There may be pain on extension of the shoulder and osteoarthritis of the shoulder may be present. Treatment is to resect the fibrosed tendon surgically, then perform rehabilitation to regain function of the limb.

Teres minor myopathy results in a consistent lameness with pain on extension of the shoulder. Sometimes the caudolateral shoulder has a firm band of tissue that is the fibrosing muscle but this may not be present. Diagnosis can be made by ultrasound examination of the tendon and muscle. The use of conservative management may only be effective early in the course of the disease and if chronic, surgery is needed to resect the fibrosing tissue.

Shoulder instability can present acutely with rupture of the medial glenohumeral ligament or as a chronic repetitive injury. Laxity can certainly occur as a congenital problem but this is more common in small dog breeds. Upon examination, abduction of the limb from the scapula greater than 35 degrees represents laxity. If the laxity is less than 45 degrees, the condition can be treated conservatively (in non-congenital cases) with hobbles or a brace for 6 weeks, then progressive rehabilitation thereafter. For more severe cases in which abduction is greater than 45 degrees, surgical treatment is warranted. Arthroscopic imbrications of the medial joint can be performed using thermal capsulorraphy, but this technique relies upon inflammation from the vapor unit-induced tissue coagulation to induce enough fibrosis to stabilize the joint. For the following 6 weeks after the procedure, the patient must be restrained and hobbled without NSAIDS treatment to induce fibrosis of the medial joint capsule. For severe cases, surgical creation of a prosthetic ligament or transposition of the subscapularis tendon is used to stabilize the joint.

Avulsion of the insertion of the flexor carpi ulnaris from the accessory carpal bone is a rare condition that presents with what looks like hyperextension of the carpus and is differentiated from palmar retinacular tears by palpating distal to the accessory carpal bone (which should palpate normally if the flexor carpi ulnaris is avulsed). Treatment consists of repair of the avulsion using a 3-loop pulley suture technique (usually with a bone tunnel created in the accessory carpal bone), then splinting for 3 weeks then rehabilitation for a gradual return to function.

Tendonitis of the abductor pollicis longus occurs in large breed dogs most commonly or in dogs with a tendency to dig in the ground frequently. This injury is not usually associated with trauma. The muscle arises laterally from the radius and ulna and crosses dorsally to insert medially on the base of the first metacarpal bone. The dog will be painful on flexion of the carpus and there will be a firm knot of tissue on the craniomedial aspect of the carpus.

Radiographs may be unremarkable even with significant stenosis of the tendon sheath over the dorsal aspect of the distal radius. Acute cases can be treated with injection of the tendon sheath with 20 mg of methylprednisolone on the distal medial radius and then the joint is immobilized for 3 weeks. If after two injections, the patient still has lameness, surgery is warranted to open the tendon sheath and remove adhesions so that the tendon is freed. Cutting the tendon is not recommended as this tendon is needed for medial intercarpal and carpometacarpal joint stability.

Disease of the elbow can be difficult to diagnose. Elbow dysplasia is a term used to describe several conditions affecting the elbow of young dogs including fragmented coronoid process, ununited anconeal process, osteochondritis dissecans of the humeral condyle, and radioulnar incongruity. Normal radiographs of young adult dogs (3 years of age) with chronic intermittent lameness suspected to be from the elbow must have further diagnostic testing, since in most cases these dogs will have early fragmented coronoid process or osteochondritis dissecans, even though no radiographic changes have occurred for a year or more.

Osteochondritis dissecans of the elbow occurs on the medial aspect of the humeral condyle of the elbow. This disease is becoming less common in the last 5 years; however, signs of lameness and pain on flexion and extension of the elbow begin as early as 5 to 8 months of age. Breeds predisposed include Burmese mountain dogs, German shepherds, Labrador retrievers, Golden retrievers, and Rottweilers. Joint capsule distention may be present at physical exam and radiographs can sometimes identify a radiolucent defect at the medial aspect of the humeral condyle. If only signs of osteoarthritis are present, further diagnostics can include computed tomography and arthroscopy.

Treatment is aimed at removing the cartilage flap and curettage of the underlying subchondral bone until bleeding occurs to stimulate fibrocartilage formation. Most commonly this is done arthroscopically and any other elbow dysplasia problem such as fragmented coronoid process is addressed at the same time. Another surgical option for these cases is performance of an osteochondral autograft taken from the  distal femur and placed in a core drilled out from the humeral condylar defect. The OAT procedure is most commonly performed with proximal ulnar osteotomy since progressive cartilage wear occurs following graft placement in many cases (especially when a fragmented coronoid is also present) and ulnar osteotomy is not performed. The prognosis for these dogs is variable, from fair to poor. Twenty to 50% of cases are bilateral. The best outcomes for these cases is obtained if surgery is performed before the onset of osteoarthritis. In most cases osteoarthritis will develop over time and result in pain and lameness.

Fragmented coronoid process is fracture of the medial aspect of the coronoid of the ulna in the elbow joint of dogs. The cause is still unknown and many theories exist. Clinical signs can begin at any time from 4 months of age to an older adult but most often there has been a history of intermittent lameness. It is most often bilateral and not associated with trauma in large breed dogs. Diagnosis can be inferred from radiographs most of the time but identification of the fragment rarely occurs with this diagnostic test. Diagnosis requires either computed tomography, magnetic resonance or arthroscopy. There are different methods to manage these cases surgically. Arthroscopy or arthrotomy can be performed to remove the fragment and debride the underlying bone to stimulate fibrocartilage formation.

Dogs with significant signs of osteoarthritis present do not generally improve following surgery. Recently, subtotal coronoidectomy has been performed as a method of treatment for fragmented coronoid process in dogs. This treatment uses a bone saw to resect the medial aspect of the coronoid and subjectively 51% of the limbs were free of lameness (subjectively) a year or more following surgery. Almost all dogs go on to develop osteoarthritis eventually, and therefore the prognosis is at best fair to poor. Another method of treatment for fragmented coronoid process is with a sliding humeral osteotomy that moves the proximal humerus laterally in an attempt to unload the medial compartment of the elbow joint. In a recent study, 66% of the dogs were sound subjectively at 26 weeks following surgery. To date, no long-term studies are available.

Ununited anconeal process is a less frequently diagnosed disease process and occurs most commonly in the German shepherd. It is most commonly unilateral and a diagnosis cannot be made before the dog is 20 weeks of age, and in some German Shepherds, the process does not fuse until 24 weeks of age. A maximum flexion mediolateral radiograph of the elbow usually makes the diagnosis. The elbow is treated surgically with arthroscopy to detect other disorders such as fragmented coronoid process and the anconeal process is lag screwed to the ulna, or if the fragment is too small to attach, it is removed. During the same surgery, a proximal ulnar ostectomy is performed with placement of an intramedullary pin to allow for correction of an length discrepancy in the ulna compared to the radius (the likely cause of the ununited anconeus). If osteoarthritis has not yet begun and the anconeal process is treated surgically, the prognosis for these dogs is good long-term.

Carpal hyperextension injuries can occur acutely from a fall or chronically in athletic dogs including dogs participating in flyball. Normal extension of the carpus is less than 10 to 15 degrees from straight. The carpal fibrocartilage and intercarpal ligaments have been torn and will heal with conservative management in a splint, however, recurrence with return to full activity is a common problem. Most cases end up needing arthrodesis for resolution of pain and return of function to the limb.16 Some dogs will need the plate removed following completion of healing since the plate can cause pain to the limb in cold environmental conditions. These dogs may not have a normal gait but do have a good return to work and life once complete healing of the arthrodesis occurs.

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