Sporting dogs and aging--what chronic problems arise and how to diagnose them early (Proceedings)

Aging is not a disease. However, in the canine athlete, it may seem that they get older faster. No one knows why for sure but lameness and reduced performance often occur quickly after the dog reaches its peak in performance. This could be the owner's desire to continue competing with an exceptional athlete or this could be the result of chronic injuries, poor conditioning and the athlete's will to compete at any cost. Shoulder lameness has been reported as a common problem in older gundogs and in agility dogs.

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. In sporting dogs, their time will be slower, they may be lame for a few days following competition, and they may miss jumps or stumble more frequently. 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. Most sporting dogs would benefit from transfixation in addition to release, therefore I perform fixation in these cases with a lag screw and washer. 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.

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 capsulorrhaphy, 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.

Patellar tendonitis may also be a more common condition than previously recognized. Signs are often subtle but may include stiffness of gait, decreased extension of the stifles, intermittent lameness, and in agility, missing jumps and obstacles. Diagnosis may be made on ultrasound or radiographs with thickening of the patella present. In cases where there has been significant fiber disruption or swelling, a period of activity restriction is warranted. At this time therapeutic ultrasound or laser can help resolve the inflammation more quickly. Build up of the quadriceps and hamstring muscles with swimming or underwater treadmill as well as developing proprioception skills are useful to rehabilitate the dog and return them to competition.

Long digital extensor tendonitis results from repetitive trauma and in severe cases the retinaculum over the proximal tibial extensor sulcus can tear and result in luxation of the tendon. This condition can be quite painful with every step and you can sometimes hear and see the tendon popping as it luxates laterally.  Several potential concurrent conditions exist including cranial cruciate ligament rupture, lateral luxation of the patella, etc. It has been reported as a presumptively congenital condition in a Siberian Husky dog. Treatment of tendonitis is supportive with rest, laser therapy or NSAIDS, and rehabilitation. The treatment of luxation involves creation of a prosthetic retinaculum over the tendon at the level of the extensor sulcus of the tibia.

Sesamoiditis is a common problem with hunting and field trial dogs and may be due to heavy repetitive training on uneven ground. Fractures of the sesamoids are not uncommon as well and can present with an acute nonweight-bearing lameness. Both sesamoid conditions result in chronic intermittent lameness long term. The most common finding is pain on palpation of the lateral and medial most sesamoids with the second and 8th on the right and second and seventh on the left limb usually affected. Radiographs will confirm the diagnosis.

Treatment is with exercise restriction and splinting for conservative management. Refractory or recurrent cases may require surgical excision of the sesamoid from the deep digital flexor tendon. As long as the tendon is not damaged during the surgery, 86% will be sound long term with minimal progression of osteoarthritis.

Spinal stiffness and pain in older sporting dogs can be a cause of decreased performance. The dogs often miss jumps, are slow to return when retrieving, and can even refuse to compete following several earlier sessions where they did well. Spondylosis is a common finding radiographically in all dogs,

In neurologic disease, more strenuous exercise will exacerbate the paraparesis; whereas, clinical signs may improve with exercise in animals with orthopedic disease. Exercise intolerance and episodic weakness are often not obvious until exercise. A stiff or stilted gait is characteristic for an animal with arthritic, muscle or neuromuscular junction disease. Animals with neurologic disease often show an ataxic gait and postural reaction deficits (specifically conscious proprioception). Concious proprioception is a nonweight-bearing test useful to discriminate between orthopedic and neurologic disease.

Lumbosacral disease or cauda equina syndrome is not uncommon in many dogs involved in many different sports. Dogs that compete or work in Schutzhund sports are very commonly affected and at younger ages, most likely due to the climbing they do and scaling of walls. Signs are lower carriage of the tail, difficulty rising and getting up and down off of furniture, stairs and cars. They may also be intermittently lame in the rear limbs and can develop urinary incontinence with later development of fecal incontinence as the disease significantly progresses.

Lower motor neuron weakness predominates the signs (sciatic, pudendal, coccygeal nerves). L7 radicular-nerve root-pain is the predominant sign initially. The dog will try to flex the lumbosacral spine to reduce compression of the nerve roots thereby reducing its ability to jump since takeoff can be very painful. Clinical signs may include biting of the tail, rump and feet. When exercising there is vasodilatation of the vasculature of the spinal cord in order to provide adequate blood to the spine and nerve roots. With stenosis of the canal due to bulging of disks and osteoarthritis of the articular facets, the nerve roots become ischemic and this is manifested as pain, lameness, and dysthesia, especially during exercise. The inciting cause of lumbosacral disease is Hansen type II LS disc degeneration followed by osteophyte formation of the L7-S1 endplates and articular processes. The syndrome is characterized by stenosis of the lumbosacral spine from vertebral subluxation and or stenotic intervertebral foramen.

Radiographs may show osteochondrosis of the sacral endplate, transitional vertebrae (in German Shepherds), and potentially instability of the lumbosacral junction on flexion and extension “stress-view” radiographs (lateral radiographs). Magnetic resonance is superior to computed tomography in its ability to visualize soft tissue. This method can provide early recognition of degenerative disc changes.

In dogs with early signs of pain on hip and tail extension but no neurological deficits and no instability on stress radiographs, rehabilitation using laser therapy, strict rest for one month followed by underwater treadmill, theraband and cavaletti exercise has been successful in 50% of my patients.

The surgery to treat lumbosacral disease involves opening up the vertebral canal with a dorsal laminectomy. The nerve roots are retracted laterally following approach via dorsal laminectomy to expose the annulus of the disc for fenestration. A foraminotomy can be performed using a burr drill or bone curette. It is important to salvage the articular facets because they are the main stabilizers of the joint. Short term outcome using a dorsal laminectomy procedure ranges from 73-93%, however recurrence can be as high as 50%.

Stabilization procedures include distraction fusion, fusion, lag screw of facets and Kishner techniques and may prevent recurrence. The prognosis is fair to good if clinical signs resolve following surgery and strict confinement is observed postoperatively. Recurrence rates vary between 3-18% in the working dog.

References

Houlton JEF. A survey of gundog lameness and injuries in Great Britain in the shooting seasons 2005/2006 and 2006/2007. Vet Comp Orthop Traumatol 2008;21:231-237.

Levy M, Hall C, Trentacosta N, et al. A preliminary retrospective survey of injuries occurring in dogs participating in canine agility. Vet Comp Orthop Traumatol 2009;22:321-324.

Marcellin-Little DJ, Levine D, Canapp SO, Jr. The canine shoulder: selected disorders and their management with physical therapy. Clin Tech Small Anim Pract 2007;22:171-182.

Rochat MC. Emerging causes of canine lameness. Vet Clin North Am Small Anim Pract 2005;35:1233-1239.

Piermattei DL, Flo GL, DeCamp CE. Brinker, Piermattei and Flo's Handbook of Small Animal Orthopedics and Fracture Repair. Fourth ed. St. Louis, Missouri: Saunders Elsevier Inc., 2006.

Bloomberg MS, Dee JF, Taylor R. Canine Sports Medicine and Surgery. First ed. St. Louis, MO: W.B. Saunders Co, 1998.

DeRisio L, Thomas WB, Sharp NJ. Degenerative lumbosacral stenosis. Vet Clin North Am Small Anim Pract 2000;30:111-132.

Sharp NJ, Wheeler SJ. Lumbosacral disease In: Sharp NJ,Wheeler SJ, eds. Small Animal Spinal Disorders: Diagnosis and Surgery. Philidelphia: Elsevier Mosby, 2005;181-209.