Approaches to the physical rehabilitation of dogs and cats with chronic neurologic and musculoskeletal disorders (Proceedings)

Chronic disorders of the musculoskeletal and neurologic systems are often classified as injuries in which the onset of clinical signs began greater than 2 weeks ago, have recurred more than once, or cannot be corrected surgically due to concurrent illness in the patient. These injures can sometimes be addressed with a rehabilitation protocol, but not all cases will respond favorably to rehabilitation and may require surgery at a later date.

Measuring the severity of the disease process prior to onset of treatment and then measuring the progress that is made is key to tailoring the rehabilitation plan to the patient and keeping the owner motivated throughout the often prolonged process of recovery. Visual analog scales for lameness and pain in the patient can be useful but objective measurements are more accurate such as muscle size, range of joint motion with a goniometer, and even force plate analysis of weightbearing on the affected limb. Whatever the method, analysis of progress made is essential to all rehab programs, especially in treated, chronically affected animals where improvements may be slow and gradual.

Rehabilitation of Chronic Neurological Disorders

Chronic fibrocartilaginous embolism (FCE) or infarction of the spinal cord has an acute onset but if the gray matter of the cord has been severely affected can result in a slow recovery and chronic neurologic deficits similar to chronic intervertebral disk disease (IVDD). Diagnosis is difficult to make in FCE but an MRI and myelogram will show focal regional spinal cord edema with no other abnormalities. Most patients that improve have had improved neurological status within the first few weeks, although some may take months to make significant improvement. Rehabilitation can help these patients and patients with IVDD improve, however, the absence of deep pain is a poor prognostic indicator in both diseases.

Rehabilitation of FCE and chronic IVDD (following surgical intervention) involves electrical stimulation of the major muscle groups affected and possibly laser therapy of the affected spinal regions. Electrical stimulation of muscles can provide nervous stimulation and muscle contraction. Electrical stimulation and laser therapy can stimulate afferent spinal tracts to speed recovery. If animals are recumbent, repositioning every 4 to 6 hours is required as well as passive range of motion (PROM) exercises. All four limbs should undergo PROM exercises to prevent contraction of muscles and tendons, and reduce edema of the limbs. A cart with a sling or a therapy ball can be used to assist the patient in a standing position with all four paws on the ground to stimulate general proprioception. Passive range of motion (PROM) exercises stimulate sensory nerves as well as muscle contraction along with deep muscle massage. Deep massage of the paralyzed limbs is very effective and should be performed at least twice daily. Manual contact of joint surfaces (through partial weightbearing such as bouncing the patient a balance ball) also stimulates general proprioception and postural reactions with contraction of muscle groups. Stimulation of proprioception also should be performed frequently, at least once a day. Hydrotherapy with a jet pool or an underwater treadmill can also stimulate sensory nerves and act to stimulate motor neuron memories.1 Always protect the patient from water inhalation by using floatation devices and having a person support the patient while in the water. While in the water the technician can also move the limbs through a normal range of motion to stimulate motor neuron memories and proprioception.

Degenerative myelopathy in dogs is a progressive disease with demyelination and axonal degeneration of the spinal cord and brain. While the cause remains unknown, the German Shepherd is over-represented for this disease. Recently, the effect of intensive rehabilitation was examined in dogs with degenerative myelopathy. Dogs undergoing intensive treatment survived an average of 255 days while dogs that did not receive any rehab survived an average of 55 days. Dogs that received a moderate regimen of physical therapy survived 150 days. The treatments included 5 to 10 minute leash walks 5 times a day, sit to stand exercises, shifting weight exercises, muscle massage 3 times a day, and hydrotherapy such as an underwater treadmill with floatation device support at least once a week.2

Rehabilitaiton of Tendon and Ligament Injuries

Complete rupture of a tendon or ligament, depending on the location, usually requires surgical intervention and do not commonly present as chronic injuries. Sprains and strains of tendons, ligaments and muscles can present as chronic lamenesses or recurrent episodes of lameness in small animals. With these injuries, permanent laxity or weakness due to inferior healing with fibrotic scar tissue can occur. In addition, muscle injuries chronically develop a fibrotic myopathy in which decreased extension of the muscle develops and a resultant short-strided gait.

Chronic tendon and ligament injuries can be treated with physical therapy but the progress of the treatment must be slow, often requiring months of progressive increase in exercises and treatments before maximal benefits can be seen. Many of these injuries can also recur if the animal does not participate in a maintenance program of rehabilitation so having a dedicated owner is a must. These chronic injuries can be addressed in three ways: 1) strengthening of the remaining normal fibers of the injured tendon, ligament, muscle, 2) strengthening of the muscles of the affected limb to provide greater support and less strain on the remaining normal fibers of the injured tendon, ligament or muscle, and 3) development of general proprioception. General proprioception allows the animal's brain and spinal cord to determine the position of the body and limbs in space and in relation to each other and provides feedback to these systems for coordinated movement and prevention of injury to supporting structures of the limb. Enhancing the body's ability to determine where it is spatially allows the brain and spinal cord to use its musculoskeletal system most effectively when walking or running. Because the brain and spinal cord learn to more effectively predict movements of the limbs in space, injury can be prevented and the safest, yet most effective, use of tendons, ligaments, and muscles occurs.3

Treatment of chronic tendon and ligament injuries begins with very slow passive range of motion exercises, first flexing the proximal and distal joints to the affected structure then extending these joints. Each flexion and extension to the point of mild discomfort should take 2 to 5 minutes. While performing these PROM, a therapeutic ultrasound or laser unit may be employed by individuals trained to use these units. The therapist may only get 2 to 3 repetitions of motion in the first week or so but the best results occur by performing these slow PROM exercises every day. It may take several months to a year to regain adequate strength and flexion depending on the severity and chronicity of the injury.1 As range of motion increases, strengthening of the muscles of the affected limb can begin. Strengthening through swimming, underwater treadmill work, or elastic bands placed across both hind limbs or both forelimbs will increase muscle mass to support and protect the injured tendon, ligament or muscle. Again, muscle strengthening should proceed very slowly, often with work only 5 minutes long per day, then slowing increasing the time, in order to prevent further injury. Finally, development of general proprioception is performed (but can begin as soon as the first week rehabilitation is instituted), by placing the patient on a balance ball (if they cannot stand on their own) or a balance board and gently rocking the animal. In addition, cavalettis can be used, first with the bars on the ground, then raising them as the patient's abilities increase, to increase range of motion and muscle strength while increasing general proprioception. Its important to remember to work slowly but progressively and not to miss many sessions or lack of recovery (and even re-injury) may occur.

An example of a tendon injury in the dog is the biceps brachii tendon. This injury is often so chronic that calcification of the tendon with repeated injury occurs and can be seen on radiographs. Early rehabilitation before most of the tendon has torn can prevent further rupture and the need for surgery. Development of the brachialis muscle to protect the tendon can prevent reinjury. Passive range of motion exercises can strengthen the biceps tendon itself and should be performed for the rest of the dog's working life. Strengthen the brachialis muscle is performed by active range of motion exercises such as walking over cavalettis (the higher the bar the more work the brachialis muscle does), swimming, underwater treadmill work, and down to sit exercises. In cases with severely atrophied brachialis muscle, electrical stimulation (e-stim) of the muscle may need to be employed.

An example of severe muscle injury is quadriceps contracture or tie down. The muscle has fibrosed to the femur and cannot flex or extend the stifle joint. Animals with this chronic condition are best hospitalized for the first two weeks of physical therapy so that they may be anesthetized three times a week and PROM exercises performed along with deep myofascial palpation. After the first two weeks when some range of motion has returned the owner may perform the exercises at home or bring the animal in to the hospital 3 times a week for treatment. Function can be returned to the limb with this method but may require 3 months or more of treatment.4

Rehabilitation of Chronic Osteoarthritis

Chronic osteoarthritis of one or multiple joints is unfortunately a common malady of dogs and cats, especially as they are living longer lives. Once osteoarthritis begins the process cannot be stopped or reversed; the best we can do is slow the progression of the disease or replace the joint surgically. Rehabilitation of these patients focuses on controlled exercise that has minimal impact on the joints since osteoarthritic joints cannot withstand compressive forces. Exercise should, however, be encouraged since muscle mass helps absorb the impact of weightbearing and protects joints from abnormal forces. PROM exercises were not found in humans to slow the progression of osteoarthritis however strength training did slow the progression of degenerative joint disease.5 The OA patient should be exercised daily on flat surfaces such as grass or soft earth that is not slippery but never on asphalt or concrete. Any jumping or leaping should be prohibited, therefore, they cannot play Frisbee or catch a flying ball. Stretching all four legs prior to these exercises with PROM can help them exercise safely. The best exercise is swimming, especially in dogs that have muscle atrophy and have not yet returned to moderate activity. Pain control is important but overzealous administration of antiinflammatories may lead to further joint deterioration.

Chronic disease in small animals is definitely problematic to treat and owner compliance is very important; however, with consistent rehabilitation, recovery or an acceptable lifestyle for the patient and the owners can be achieved.

References

1. Millis DL, Levine D, Taylor RA. Canine Rehabilitation and Physical Therapy. First ed. St. Louis, Missouri: Saunders, 2004.

2. Kathmann I, Cizinauskas S, Doherr MG, et al. Daily controlled physiotherapy increases survival time in dogs with suspected degenerative myelopathy. J Vet Intern Med 2006;20:927-932.

3. Goff L, Stubbs N. Animal Physiotherapy. First ed. Oxford: Blackwell Publishing, Ltd., 2007.

4. Edge-Hughes L, Nicholson H. Canine Treatment and Rehabilitation In: McGowan C, Goff L,Stubbs N, eds. Animal Physiotherapy Assessment, Treatment, and Rehabilitaiton of Animals. First ed. Oxford, UK: Blackwell Publishing, Ltd., 2007.

5. Mikesky AE, Mazzuca SA, Brandt KD, et al. Effects of strength training on the incidence and progression of knee osteoarthritis. Arthritis Rheum 2006;55:690-699.