March 2007 Physical Therapy Darryl L. Millis, MS, DVM, Diplomate ACVS, CCRP Professor of Orthopedic Surgery University of Tennessee College of Veterinary Medicine Physical Rehabilitation WHY PHYSICAL REHABILITATION? Much attention has been directed to the preoperative and operative management of surgical patients, but very little attention has been focused on the postoperative rehabilitation of veterinary patients. Physical therapy in human patients is common and well accepted. Until recently, there has been little study of physical rehabilitation of animals. Advances in the management of people receiving physical therapy have allowed us to adapt some of the techniques and procedures to small animals. Many changes occur in the musculoskeletal system of patients recovering from orthopedic surgery or those afflicted with chronic conditions. Although there are many potential situations in which physical rehabilitation may be used in animals, this discussion will primarily concentrate on orthopedic and neurologic patients. Pathophysiology of Tissue Disuse and Recovery Musculoskeletal tissues, including cartilage, muscle, bone, ligaments and tendons, undergo tremendous change as a result of injury or following surgery. Following treatment and during recovery, tissues attempt to revert back to their preinjured state. Knowledge of the character and timing of these events is important to help the surgeon appreciate the changes that occur and use this knowledge to develop rehabilitation protocols to quickly return the patient to function. Cartilage Changes Caused by Immobilization and Disuse Limb immobilization results in degenerative changes of articular cartilage. These changes are more marked and appear sooner in areas of contact, but they also occur in other areas. Joint immobilization also results in reduced synovial fluid production and decreased diffusion of synovial fluid and nutrients into the cartilage as a result of decreased pumping action. Immobilization of a limb in extension results in changes similar to those seen in osteoarthritic cartilage, including osteophyte formation, fibrillation, pitting, and erosion of articular cartilage. In contrast, immobilization of a limb in flexion does not lead to changes similar to osteoarthritis. However, atrophy of cartilage does occur with immobilization in flexion. The changes arising from immobilization in flexion are probably not due to lack of joint motion but to reduction in the normal loading of cartilage. The cartilage changes that occur with immobilization of a limb in flexion are reversible if joint motion is allowed and dogs are allowed to ambulate. In one study, casting with a limb in flexion for 3 to 8 weeks resulted in progressive cartilage atrophy. Cartilage from the immobilized joints was grossly normal with no osteophytes. Proteoglycan (PG) content and cartilage thickness were reduced 30 and 29%, respectively, and net PG synthesis was reduced 37%. The subchondral bone was also markedly atrophic. Cartilage from the contralateral limb also had a lower PG content, probably due to prolonged increased loading. When allowed to ambulate for 3 weeks after cast removal, the cartilage became normal, indicating that remobilization reverses the cartilage atrophy. In contrast, cartilage from dogs which are run daily (6 miles/day at 3 mph) on a treadmill for three weeks after cast removal has continued decreases in cartilage thickness (20%) and PG content (35%) even though net PG synthesis is 16% greater than in cartilage from contralateral non-immobilized knees. Therefore, vigorous loading of joints following immobilization may prevent recovery of cartilage damage. In another study, stifles were immobilized for 6 weeks by applying a cast, which allowed 80 to 150 of motion, or external skeletal fixators, which were more rigid. After 6 weeks, PG was 23% and 28% lower, in the cast and external skeletal fixator groups, respectively. Immobilization by casting resulted in a smaller decrease in PG synthesis and less PG loss during immobilization as compared to the more rigid external skeletal fixation immobilization. The limited motion afforded by cast immobilization was protective to cartilage during recovery. During a 1 week recovery period, PG content almost returned to normal. In contrast, cartilage of joints immobilized with ESF had little or no recovery of PG. Whenever possible, immobilization should be applied for the shortest time possible and should allow up to 100 joint motion. Muscle Changes Caused by Immobilization and Disuse Many animal models have evaluated the effects of decreased mechanical loads on skeletal muscle. Muscles which are recruited to maintain upright posture during weight bearing are impacted more by immobilization. In general, extensor muscles are comprised mainly of type I muscle fibers and they are more susceptible to reduced mechanical loads than are muscles with mainly fast twitch fibers. Muscle atrophy is common following surgery. For example, in one study, dogs undergoing transection of the cranial cruciate ligament and immediate stifle stabilization with an extracapsular repair had loss of 1/3 of muscle mass in the affected limb with in 5 weeks. The muscles most susceptible to atrophy were the quadriceps, semitendinosus and semimembranosus muscles. In addition to muscle atrophy, there is a loss in muscle force production, which is partially but not completely accounted for by the loss of muscle mass. Despite normalizing to muscle mass, peak tetanic force may be reduced by 50% following removal of weight bearing activity. The exact cause of the reduced contractile force is unknown, but may be related to changes in cellular components. Ligament and Tendon Changes Caused by Immobilization and Disuse Immobilization following musculoskeletal injury results in an adverse decline in structural and material properties of ligaments and tendons. Along with the changes in cartilage, bone, and joint capsule (fibrosis and stiffening), there is a decrease in biomechanical performance of ligaments and tendons. For example, the effect of immobilization on the ACL of primates was studied by placing animals in a body cast for 8 weeks. Remobilization was allowed for 5 or 12 months. Following 8 weeks of immobilization, there was a 39% decrease in load to failure and 32% decrease in energy stored to failure. In addition, the ligaments were significantly less stiff. Following 5 months of rehabilitation, load to failure and energy stored at failure were 79% and 78% of normal, respectively. Following 12 months of rehabilitation, ligaments were nearly normal with 91% and 92% of normal load to failure and energy stored to failure, respectively. In another study, the effects of immobilization on the cranial cruciate ligament using internal skeletal fixation for 12 wks were studied in dogs. Failure of the ligament-bone complex occurred through the tibial insertion of the ligament. The load at failure and stiffness were 45% and 73% of non-immobilized ligaments. Greater loss of collagen occurred at bone insertion sites. Cast immobilization for 12 weeks caused changes in the tibial insertion of the cranial cruciate ligament, including many osteoclasts, large fibroblasts, replacement of bone with fibrous tissue, and attachment of the ligament to the periosteum only. Other studies have shown that up to one year of remobilization is required for normalization of the ligament-bone complex. Conversely, ligament mechanical properties return to normal more quickly. There appears to be asynchronous healing of the bone-ligament-bone complex following immobilization. Knowledge of these detrimental effects of immobilization has influenced our current management of ligament and tendon injuries. Bone Changes Caused by Immobilization and Disuse Immobilization of limbs also results in decreased bone formation and normal or increased bone resorption due to greater osteoclastic activity. Because of a higher ratio of cancellous to cortical bone, trabecular bone is generally more affected than cortical bone. Remodeling occurs on endosteal, Haversian, and periosteal surfaces, and is more extensive in the distal bones. The effects of immobilization appear to be greater in immature animals. In general, if a bone is immobilized for 6 weeks, there is rapid loss of bone, but near full recovery by 8-12 weeks. If the bone is immobilized for 12-32 weeks, bone loss slows, and there is a longer recovery. If bone is immobilized for longer periods (>32 weeks), bone loss is maintained at 30 - 50 % of normal and complete recovery is unlikely. Bone loss in older patients is less, but there is also less recovery of bone mass. Bone loss routinely occurs following such procedures as cranial cruciate ligament rupture, and is more prominent in metaphyseal regions. Bone loss tends to lag muscle atrophy, but bone loss continues after muscle mass begins to return. Bone loss can also result from stress shielding or stress protection. Bone resorption is evident by 6 weeks after application of a bone screw. Bone loss is even greater following application of a bone plate, and the recovery is slower following removal. Establishing a Physical Rehabilitation Team Veterinary technicians and veterinarians receive virtually no training in physical therapy techniques. Similarly, physical therapists do not receive training in veterinary medicine. Therefore, it is important to develop collaborative working relationships to advance the care of postoperative veterinary patients. The AVMA House of Delegates passed guidelines for alternative and complementary veterinary medicine in 1996 which state that veterinary physical therapy should be performed by the veterinarian, a licensed veterinary technician, or a licensed physical therapist educated in animal anatomy and physiology under the supervision of a veterinarian. New guidelines were adopted in 2001. They evaluated several medical approaches described by the terms "complementary," "alternative," and "integrative" and collectively described them as Complementary and Alternative Veterinary Medicine (CAVM). Examples of CAVM include aromatherapy; Bach flower remedy therapy; energy therapy; low-energy photon therapy; magnetic field therapy; orthomolecular therapy; veterinary acupuncture, acutherapy, and acupressure; veterinary homeopathy; veterinary manual or manipulative therapy (similar to osteopathy, chiropractic, or physical medicine and therapy); veterinary neutraceutical therapy; and veterinary phytotherapy. Collaborative efforts are also supported by the American Physical Therapy Association. A new position statement in 2005 states that"The American Physical Therapy Association acknowledges the collaborative relationships of physical therapists and veterinarians and the evolution of the specialized practice by physical therapists in animals rehabilitation. Consistent with the Mission Statement Fulfillment Policy adopted by the House of delegates to enable physical therapists to improve their knowledge and skills in interest of furthering their professions, the practice of animal rehabilitation by physical therapists is permissible where allowed by law and regulation." Therefore, although postoperative rehabilitation of veterinary patients is supported by both professions, clearly there is the need for collaborative relationships to provide the best therapeutic plan possible. It is beneficial to locate a physical therapist who has an interest in working with animals to instruct veterinarians and veterinary technicians on the proper use of therapeutic modalities. The attending veterinarian is often the primary person responsible for decisions regarding appropriate rehabilitative care. Depending on the injury and repair, specific recommendations are given to the person responsible for the rehabilitation. Precautions to therapy, especially exercises, must be clearly communicated. When veterinarians initiate physical therapy in their practices, the initial sessions should be performed with all team members present as differences in terminology may cause confusion and possibly result in injury. For example, performing ROM exercises may have different meaning to veterinarians, owners, and physical therapists. Communication and documentation between the team members is critical, and forms, such as those listed in this chapter, provide an easy way to facilitate this. The team approach involves a group evaluation or an assessment of the same patient by two or more clinicians within a short time of each other. A core group of clinicians - for example, a veterinarian and a physical therapist, and veterinary technician - is identified as the initial team. The initial team then documents their findings, meets and decides together the most effective plan for intervention. The core group may request additional evaluations by other experts on the team on an individual case basis. The appropriate clinicians are chosen to initiate the intervention plan. The team reviews the progress of the client periodically. One member of the team is responsible for follow-up after discharge. This team approach allows for a variety of perspectives on health care issues. The team offers the client a detailed interdisciplinary assessment as well as the most cost efficient method of providing services to resolve or treat the problem. MODALITIES USED IN PHYSICAL REHABILITATION Thermal Agents The use of thermal agents in rehabilitation is widespread, and the goal is to transfer energy to a patient to produce either an increase or a decrease in tissue temperature. Depending upon the tissue that you wish to affect, and its stage in the recovery process, a particular thermal agent is chosen. Thermal agents that increase tissue temperature are commonly applied to increase the metabolism in the area, increase blood flow to the area, increase soft tissue extensibility, and decrease pain. Thermal agents that decrease tissue temperature are typically applied to decrease metabolism to an area, decrease swelling, and decrease pain. Superficial Heat Superficial heating (thermotherapy) increases temperature of the skin and underlying subcutaneous tissues with little change in the temperature of the deeper structures. Superficial heating agents are capable of increasing temperature up to depth of 3 cm, with the greatest amount of increased temperature from the surface to 0.5 cm. Heat is transferred to the tissues by several methods. The most common method is conduction, which is the transfer of heat by the direct interaction of the molecules in the hot area with those in the cooler area (e.g. hot packs, cold packs). Convection is the transfer of heat through the use of liquids or gases (e.g. whirlpool, circulatory system). Radiation involves the transmission and absorption of electromagnetic waves (e.g. infrared, ultraviolet) that occurs when there is a difference in temperature between the skin and surrounding environment. Superficial heat is typically used: 1) to heat joints that have relatively little soft tissue covering such as the carpus; 2) for relaxation effect and to provide temporary pain relief; 3) prior to stretching of superficial structures. The physiologic changes will be dependent upon the extent of the temperature rise, the rate at which the energy is being added to the tissue, and the volume of tissue exposed. Heat causes vasodilation, which may improve healing through the increased oxygenation and nutrients brought into the area, and by the removal of waste products. Cellular chemical activity and metabolic rate generally will double for every 10EC rise in temperature. This increase in enzyme activity and biochemical reactions may speed the healing process if applied at the correct time. It can also be potentially harmful if used too early (during the acute inflammatory phase). In humans, collagenase shows increased activity at 36EC (inflamed knee 34-38EC) compared to 30EC (normal knee temperature). Temperature elevation may alter the viscoelastic properties of connective tissue and increase tissue extensibility, resulting in decreased joint stiffness and increased ROM. To stretch connective tissues utilizing heat, stretch should be applied during or immediately after heating, as the effect is short-lived. When heat is applied, less force is necessary to get a significant residual elongation of tissues. Stretching connective tissue while heating results in less tissue damage than stretching without heat. Heat can be applied in the form of hot packs, warm baths or whirlpools. The typical treatment time is twenty minutes, and stretching should be incorporated into the latter half of the treatment if increased ROM is a goal. Indications for heating tissues include subacute and chronic traumatic and inflammatory conditions, muscle spasm, tissue tightness, adhesions, and pain. Contraindications/precautions to heat include acute inflammation (may exacerbate the edema), decreased or absent sensation, over malignancies, over areas of active infection, and over areas with compromised circulation. Cryotherapy The use of cold as a therapeutic agent is called cryotherapy. When cold is applied it lowers the temperature of skin and underlying tissues by removing heat from the body. The primary modes of energy transfer used for therapeutic cooling include conduction, convection, and evaporation. Decreases in temperature obtained typically vary between 1-4EC intramuscularly and 12-13EC at the skin, with a return to baseline temperature in 15-30 minutes (in humans). A study of dogs in which a cold pack was placed on the caudal thigh muscles for 20 minutes, skin temperature decreased 14.20C. At the 1.0 and 3.0 cm tissue depths, tissue cooling was less profound but still statistically significant, being 2.3 and 1.6 degrees Celsius at 1.0 and 3.0 cm, respectively. Temperatures at both 1 and 3 cm depths continued to decrease for 10 minutes following cold pack removal until they plateaued for 60 minutes, and then ascended back toward baseline. Cold is the thermal agent of choice in the management of acute injuries because: 1) The resulting arteriolar vasoconstriction reduces bleeding; 2) The decrease in metabolism and vasoactive agents (e.g. histamine) reduces inflammation and outward fluid filtration; 3) It decreases pain through a number of mechanisms, and 4) It may decrease muscle spasm. At a temperature of 30EC (86EF) or lower, inhibition of cartilage degrading enzymes (protease, hyaluronidase, collagenase) is seen in humans. To enhance cooling of tissues, a wet towel can be placed between the cold pack and the skin; because water is an excellent thermal conductor, the temperature change is more pronounced. Cold may also be applied using convection in the form of cold baths or whirlpools. Treatment time varies based on the modality chosen and the size of the treatment area. For larger areas such as the caudal thigh muscles, ice massage would not be a time effective treatment because it could take as long as thirty minutes to achieve effective cooling. Indications for cryotherapy include musculoskeletal trauma, orthopedic surgical swelling/pain, pain due to muscle spasm, and limitation of motion secondary to pain, and edema. Compression wraps are typically added to cryotherapy treatments to further assist in minimizing edema (the increased extravascular pressure helps control edema formation and promotes resorption of fluid). Contraindications/precautions to cold include cold hypersensitivity, decreased or absent sensation, previous frostbite in the area, and over areas with compromised circulation. Range of Motion and Stretching Increasing joint ROM through stretching affects numerous tissues including muscles, articular surfaces, joint capsules, ligaments, fascia, blood vessels and nerves. Early continuous passive ROM within a pain-free range is beneficial to the healing and recovery of many soft tissue and joint lesions. Early controlled movement along normal lines of stress results in a stronger scar in a variety of connective tissues. Early post-operative ROM is also beneficial to maintain existing joint and soft tissue mobility, and to minimize the effects of contracture formation. To maintain normal ROM, the segments must be moved through their available ranges at least daily. Stretching techniques are often performed in conjunction with ROM exercises to improve flexibility of the joints and extensibility of periarticular tissues, muscles, and tendons. Stretching is performed to elongate pathologically shortened tissues, and to increase flexibility and joint motion. Stretching takes tissues beyond the normal ROM. Caution should be used to avoid stretching too rapidly, which may cause tissue damage or stimulation of the muscle spindle and an increase in muscle contraction. Static stretching involves placing the joint(s) in a position so that the muscles and connective tissues are stretched while held with the tissues at their greatest length for 15 to 30 seconds. After stretching, the tissues are allowed to return to a neutral position, and then the stretch is re-applied for up to 20 times in a session. A stretching program performed 3 to 5 times per week may increase flexibility. Prolonged mechanical stretching is a low intensity stretch applied for a minimum of 20 minutes and up to several hours. In animals, splints or other coaptation devices may be applied to provide prolonged stretching. Heating tendons prior to stretching may result in less tissue damage and greater elongation. Therapeutic ultrasound is frequently used to warm tissues for stretching. THE SCIENCE OF THERAPEUTIC EXERCISE Therapeutic exercise is perhaps one of the most valuable modalities used in canine physical rehabilitation. Some of the common goals of therapeutic exercise are to improve active pain-free range of motion, muscle mass and muscle strength, balance, performance with daily function, aerobic capacity, help prevent further injury, and to reduce weight, and lameness. Common activities include standing exercises, controlled leash activities, stair climbing, treadmill activity, "wheel barrowing" (for forelimb activity), and "dancing" (for rear limb activity). Other activities include jogging, sit-to-stand exercises, pulling or carrying weights, walking and trotting across cavaletti rails, playing ball, taping a bottle or syringe cap to the bottom of an unaffected foot to encourage weight bearing, slinging the contralateral good limb, and using balance balls or rolls. In addition to being an important method to assist an animal's return to the best function possible, the equipment needed for therapeutic exercise is relatively inexpensive and similar principles apply to a variety of individuals and conditions. Therapeutic exercise programs designed for the home environment also provide an opportunity for owners to become actively involved in their pet's rehabilitation. When designing a therapeutic exercise program, several factors must be considered. A problem list is developed based on an initial evaluation of the rehabilitation patient and a treatment plan is formulated to address the identified problem(s). Realistic outcome goals are then established. Therapeutic exercise is a significant component of the treatment plan. Appropriate exercises are those that can be performed safely and effectively, and accomplish the therapeutic goals. When prescribing therapeutic exercise, the therapist should understand of the diagnosis, identify the structure or structures involved, and recognize the stage of tissue recovery with the resultant functional limitations. With this knowledge and understanding, appropriate decisions may be made regarding therapeutic exercise choices. Treatment considerations and choice of exercises vary with each stage of tissue repair and endurance. As the animal improves clinically and tissue healing progresses, the exercise plan should be altered to match the animal's progress and appropriately challenge the involved tissues. The intensity of an exercise may be increased or reduced by changing the duration of time that an animal performs an exercise, the frequency that an exercise is performed, and the rate of speed that a particular exercise is performed. Any of these may be altered to fine-tune an exercise prescription to achieve the expected outcome goals. For example, a realistic initial goal for a morbidly obese, deconditioned patient with degenerative joint disease may be to increase the amount of time the dog is able to comfortably tolerate walking, thus improving endurance and promoting weight reduction; increasing the speed at which the dog walks may not be a realistic initial goal for this animal. A contrasting exampl,e may be an athletic animal recovering from injury that must be challenged to improve speed and frequency to meet the goal to return to performance activity. It is important for the therapist to have an understanding of exercise intensity and what is appropriate for each patient during rehabilitation treatment. Routine re-evaluation of the patient is recommended to evaluate the adaptations that are occurring with the rehabilitation treatment plan and to determine the appropriate rate of progression. Therapeutic exercise routines should be monitored at regular intervals by a trained individual that is familiar with the patient and the exercise techniques. Inappropriate exercise or improper technique may result in inappropriate stresses, further injury, or exacerbation of an existing condition. Certain exercises may not be safe for the strength, flexibility, or endurance level of the animal performing the exercise or it may be an incorrect exercise to accomplish the intended goal. Assisted Standing Exercises Patients with severe injuries or conditions may not be able to stand and support their own body weight. A period of standing, either completely or partially assisted, may result in strengthening, aid in proprioceptive training, improve circulation and respiration, provide an opportunity to eliminate, and enhance the patient's psychological well-being. The purposes of assisted standing exercises are to encourage neuromuscular function, re-educate muscles, develop strength and stamina of supporting muscles, and enhance proprioception. Animals with multiple orthopedic injuries, neurologic conditions, or severe debilitation are excellent candidates for assisted standing exercises. Assisted standing exercises are among the first therapeutic exercises prescribed for severely afflicted animals which are not able to completely bear weight and may begin in patients that are receiving adequate pain control following injuries which are stable. Animals which are painful resist standing and may further injure themselves or the therapist while struggling. It is appropriate to begin assisted standing exercises in patients with adequate muscle tone and some ability of the limb(s) to resist motion (adequate upper motor neuron function). Patients with lower motor neuron signs have little or no muscle tone and flaccidity of the limbs. Although patients with lower motor neuron conditions will likely benefit from standing exercises, it is unlikely that they will be able to fully support their weight and some additional assistance will be required. Body Slings Nonambulatory patients may benefit from placement in a body sling to provide support for standing. An advantage of a sling is that the patient is able to maintain a sternal body position with the limbs placed under the body in a standing position, which may provide an opportunity for limb strengthening and early proprioceptive training. Frequent episodes of supported standing also help to relieve pressure on bony prominences and may reduce the chances of decubital ulcer formation. Excessive congestion of the lungs which may result from spending long periods in lateral recumbency may be prevented with early implementation of standing in a sling. The body sling must be adjusted properly so that respiration is not compromised and the limbs are not compressed in the openings in the sling. Proper padding is also important for comfort. The skin should be inspected after each session in the sling to identify areas of potential skin irritation or breakdown. Rubber bungee cords may be used to secure the sling to the supporting frame. This may aid in the facilitation of weight bearing and movement during the sling sessions. The elasticity of the cord permits some gentle up and down movement which encourages the animal to safely bear partial weight on its limbs. It also may allow some attempts to move forward, backward, and side to side. A gentle bouncing motion may be manually introduced by the therapist to initiate rhythmic stabilization of muscle groups throughout the trunk and limbs. Maximal Assisted Standing Maximal assisted standing is appropriate for patients which are unable to support their body weight as a result of paralysis, paresis, pain, trauma, post operative precautions, or general debilitation. Maximal assistance may be defined as support of 75 to 100% of the patient's body weight by the handler to maintain a standing posture. Maximal assisted lifts and standing are initially required for patients that are unable to independently rise from a recumbent position or support their own body weight. Common indications include paralysis, paresis, or general debilitation. Depending on animal size and weight, the handler can manually lift or use an assistive device such as a sling or towel to assist the animal from a recumbent to a supported standing position. To perform standing exercises, a sling or towel is placed under the cranial thorax, caudal abdomen, or both for conditions affecting the forelimbs, rear limbs, or both, respectively. After the animal is in a supported standing position, the handler or a second person manually places the animal's limbs in a normal stance position, with the feet positioned squarely on the ground. Even distribution of the animal's weight on the ground may provide position sense, which is proprioceptive input facilitating the animal's awareness of its joints at rest. The animal should be encouraged to support its body weight as able and the therapist gives only the necessary assistance to maintain the standing position. While supporting the animal, the handler slowly releases tension on the assistive device, allowing the animal to continue weight bearing as much as it is able. Because the animal is encouraged to accept and support a portion of its weight, strength, balance, coordination, and proprioception are challenged. If the dog begins to collapse, the sling is gently pulled up to assist the patient back into the standing position and the exercise repeated. During a treatment session, the animal may need periods of rest and should be allowed to lie down during these times. Although the duration of each session should match the animal's tolerance, an initial starting goal is 10-15 repetitions two to three times daily and gradually increase to 5 minutes per session. Individual patients progress at different rates. The therapist can keep track of and document the amount of time the animal is able to stand and how much assistance was needed. Active Assisted Standing As the animal becomes stronger and regains neuromuscular function, maximal assistance from the handler is not required. The progression from maximal assisted standing to active assisted standing occurs when the animal is able to actively support some of its weight, requiring only partial assistance from the handler (less than 75% of body weight). The animal should be encouraged to support as much of its weight as possible. The handler provides only the additional assistance required to maintain a standing position. The amount of assistance required is documented by recording the actual weight the handler is required to support for the animal to maintain a standing position, as well as the length of time the animal can maintain a standing position. The animal may require periodic rests during a treatment session. As the animal's strength and endurance improve, the duration of each session may be increased, the number of rest periods decreased, and the amount of assistance decreased. Active Assisted Standing Using Exercise Rolls A properly fitted inflatable exercise roll (Physio-roll) may also be used to actively assist the animal with stance, weight bearing, and weight shifting. Using the roll as an assistive device also relieves stress on the handlers. Unless the animal is small, this technique may require two people to properly assist the patient. The animal is placed in a standing position over an appropriately sized exercise roll (the roll provides greater lateral support and stability than a round exercise ball). The size should allow the animal to touch the ground with all four feet. If the roll is too tall, the roll may be deflated to meet the animal's height. Rolls that are slightly deflated are softer, more stable, and easier to work with than those that are fully inflated and very firm. The softer roll conforms to the animal's body better and is more comfortable. After the animal is secure on the roll, one person stabilizes the front of the animal and another stabilizes the rear. While the animal is supported in a standing position with paws on the ground, the handler can generate a very gentle up and down bouncing motion through the patient and the inflated roll. This provides proprioceptive input, and may stimulate contraction of the supporting limb muscles. Weight bearing in the thoracic or pelvic limbs may be promoted as the therapists shift the roll forward and backward. As the animal becomes stronger, these same techniques may be performed at faster speeds to provide greater challenges to neuromuscular function and balance. Proprioceptive Training When an animal is able to stand independently (without assistance) and safely, activities to improve balance may begin. Dynamic balance is the animal's ability to maintain balance while the body is moving, such as while walking. The following exercises may be performed to challenge the animal's dynamic balance. These exercises should be conducted on a non-slip surface to provide adequate traction and reduce the risk of falling. Weight Shifting While the animal is standing, a treat may be used to encourage weight shifting. The interested dog will follow the treat side to side, and up and down. Start with small movements, and progress to larger, more challenging movements. The movement of the head causes the dog's center of gravity (COG) to shift. As the COG shifts, the dog must shift its weight to maintain its balance. To maintain the unassisted standing position, the animal is required to use strength, coordination and balance. If the dog is motivated by ball play, a more challenging form of this exercise is close distance ball tossing from above and the sides. During early attempts at these exercises it may be necessary to have someone available for standby assistance as the dog may be over-challenged, lose its balance, and fall. The handler may also attempt to disturb the animal's balance by gently pushing the animal at the hips or shoulder. The goal is to disturb its balance just enough so the animal can recover, being careful not to push with a force that may cause the animal to fall. Generally, pushing the animal to the more affected side challenges the animal sufficiently to allow the activity to have the desired effect. Some dogs become conditioned to this activity, however, and shift their weight toward the therapist to prevent being pushed toward the affected side. In this case, a rebound weight shift may be effective. For this maneuver, the therapist gently pushes the animal toward the affected side. When the animal shifts its weight to resist the movement, the therapist suddenly releases pressure, and simultaneously pushes gently toward the unaffected side. This results in a sudden unbalancing; the animal initially shifts its weight toward the unaffected side, but to keep from falling, it immediately shifts its weight back toward the affected side. Additional challenges may be added by slowly moving a supporting towel back and forth ("shoe buff" maneuver), in a motion similar to buffing a shoe, to force the dog to shift its weight back and forth. Weight shifts may also be performed during walking. As the animal is walked in a straight line, the handler gently bumps or pushes the animal to one side to challenge the dog to maintain its balance. Caution should be used to tailor the force of the push with the animal's stage of recovery to avoid falls and injury. Manual Unloading of One Limb During Stance Lifting and holding a single limb off the ground while the dog is standing causes a shift in the animal's COG. The animal shifts its body weight and COG to maintain the standing position. During a session, the handler may lift each leg separately to see where the animal is the weakest and focus on that area in successive sessions. If the animal is unable or unwilling to perform this exercise, it will not shift its weight properly, but instead will bear the weight on the handlers hand or collapse to the ground. A technique to avoid bearing all of the weight on the handler is to slowly abduct the raised limb, which allows transfer of weight from the handler to the desired limb to avoid falling. Balance Board A platform on rockers may be used to rock the dog forward and backward, side to side, diagonally, and 3600. This is similar to a human BAPS board. In fact, a BAPS board may be used to help the animal practice proprioceptive positioning on just the forelimbs or the hind limbs by placing the desired limbs on the board while the other limbs remain on the ground. If the goal is to have the animal exercise using all four limbs, then a specially made platform must be used to accommodate quadrupeds. It is important to have one person help support the dog while another person slowly and gently rocks the platform to allow the animal an opportunity to shift its weight and exercise its proprioceptive mechanism. Exercise Balls and Rolls Therapeutic exercise balls and rolls, designed for human use, may be used to improve balance, coordination, and strength. They may also be used for general stretching. The forelimbs are placed on the ball and supported by the handler, requiring the dog to maintain static balance of the caudal trunk and rear limbs. Dynamic balance may also be challenged as the ball or roll is slowly moved forward, backward, and side to side, challenging the rear legs to maintain balance while movement occurs. To address the cranial trunk, head, neck and forelimbs, the rear limbs are placed over the ball as the forelimbs are asked to balance the body weight during both stance (static) and gentle movements (dynamic). Dynamic Ambulation Activities Assisted Ambulation/Gait Training If a dog is unable to walk independently, an assistive device may be used to support the animal as needed. Gait training should begin with the use of a sling, towel, harness, or canine cart. The handler should assess the animal's needs before choosing the appropriate device. Encourage the dog to move slowly, allowing time for the dog to advance the limbs as independently as possible. Allow adequate time for the feet to come in contact with the ground with each step during the stance phase of gait. It may be necessary for the handler to manually assist the dog in the sequencing and placement of the limbs as the animal relearns the walking gait. If the animal moves too quickly, it will often avoid bearing weight on a painful limb, adopting an abnormal gait, such as a three-legged lameness, hopping, or dragging of a limb. The emphasis is on weight-bearing with each and every step, encouraging a slow gait. It is important for each person handling the dog to be consistent and not allow the dog to move too quickly. Walking Slings Commercially available canine slings should be durable, flexible, washable, and conform to the body. They are available for the forelimbs, hind limbs, and for trunk support. Rear slings should have a recessed area so bowel and bladder function is not obstructed. Adjustable length handles for the therapist to grip make slings a more ergonomic choice of assistive device than bath towels because they allow the handler to stand erect without bending forward while carrying the weight of the dog. This is an important concern especially if the handler will be assisting a large dog several times a day for any length of time. It is important for those persons handling the animal to practice proper body mechanics while assisting the canine patient to avoid unnecessary injury. The sling may be used for both orthopedic and neurological patients in need of assisted ambulation. Towels A long towel may be used to support an animal requiring assistance with standing or ambulation. Towels are readily available, inexpensive and washable. When assisting the dog's hind limbs, the towel should be placed around the abdomen just in front of the hind limbs in the inguinal region. Nylon straps may be sewn on to the ends of the towel to provide added length so the handler can maintain proper body mechanics. A disadvantage of towels on larger dogs with urinary incontinence is that it puts pressure on the urinary bladder and may cause it to be expressed. This is less likely to happen with a properly fitted commercial sling. Also, towels may not be as comfortable for the handler. Independent Ambulation Leash Walking Slow leash walks are perhaps the most important exercise in the early rehabilitative period, and they are commonly performed incorrectly. Walking the animal slowly encourages the use of all limbs in a sequenced gait pattern. Walks must be slow enough to allow weight-bearing; if the dog is walked too fast, the tendency is to simply hold the limb up in a flexed position and not bear any weight on the intended limb. Slow leash walking is indicated when the animal is reluctant to use a limb secondary to pain, weakness, or proprioceptive deficits. Slow leash walks encourage placement of each limb on the ground, increasing stance time and weightbearing. If there are no contraindications to weightbearing, slow leash walks may begin very soon after most orthopedic procedures. Behavior modification is important. The dog should be praised when touching the limb to the ground, and not praised when the leg is held up. As the animal regains use of the affected limbs and is consistently able to place the limbs at a slow leash walk, the pace of the walk may be increased. Faster walks further challenge balance, coordination, proprioception and cardio-respiratory endurance, as well as functional muscle strengthening and endurance. When appropriate, the therapist may alter the exercise treatment plan to include fast walking, slow jogging and running on a long lead. Inclines And Declines Walking or jogging the dog up inclines aids in strengthening of the quadriceps, semitendinosus, semimembranosus, and gluteal muscles with relatively low-impact activity. Muscle strength in the hips and stifles is required for the dog to propel itself up an incline. Walking should be done slowly and on leash, otherwise the dog may only toe-touch with the limb or hop in a non-weight bearing fashion. In addition, if the head is held up slightly, the weight will be shifted caudally and require the animal to drive up the hill with the rear limbs and use the muscles to a greater extent. Weight-bearing while climbing promotes extension at the knee and hip. When the limb is in the stance phase of gait and the body is traveling forward, the knee and hip must extend to propel the animal forward. If extension is painful, the dog's stance time on the limb is shortened and an altered gait results. Inclines and declines should be introduced slowly, beginning with gradual inclines. As the dog's range of motion and strength improve, the dog may be challenged by walking up longer, steeper slopes, and by increasing the duration and speed of the climbing exercise. Walking down inclines is typically more difficult because it requires the dog to reach under the body with the hind limbs, requiring flexion of the hock, stifle, and hip. Start with gently sloping, short declines, and progress to steeper ones as the dog is able. Standing or Walking on Foam Rubber, Mattresses, Air Mattresses Altering the texture of the ground surface over which the animal walks provides a challenge to the animal's functional walking proprioceptive ability. Standing or walking on foam rubber egg crate mattresses, normal bed mattresses, air mattresses, and trampolines allow the animal to negotiate various surfaces which have some resiliency. Having different surfaces on either side of the animal while walking, or changing the type of surface the animal must negotiate with all limbs during a walk provide additional challenges that may be integrated into the rehabilitation program. Stair Climbing As the dog consistently begins to use the affected limb or limbs at a walk with decreasing lameness, and is able to walk inclines and declines with minimal difficulty, stairs may be added to the treatment plan. Climbing stairs is useful to improve power in the rear limb extensors, range of motion, coordination and balance. Quadriceps and gluteal muscle groups are strengthened as the animal pushes off, extending both hips and knees while propelling the body weight up the steps. Stair climbing may begin if the repair is stable and the dog is consistently using the limb at a walk with progressively decreasing lameness. The dog must begin slowly climbing stairs to encourage proper use of the rear limbs, as opposed to simply carrying the limb, hopping with both hind limbs, or skipping up stairs. Encourage the dog to go slowly and deliberately, climbing the stairs in a reciprocal stepping gait. Stairs should be introduced slowly because this is a challenging exercise for both the musculoskeletal and cardiovascular systems and the animal may fatigue quickly. Initially, some dogs may require assistance from the handler. Begin with 5-7 steps, and gradually increase to 2 to 4 flights of stairs once or twice daily. Treadmill Walking Walking on a treadmill is very useful in rehabilitation. Most dogs trained to a leash readily take to treadmill walking in one or two sessions. A variety of treadmills are available for use, including commercial canine treadmills. A number of models available for human use may be modified for canine use by adding an overhead bar with a support system to which a canine harness can attach. A harness is useful to help support the dog in case it stumbles or falls. Side rails or fences placed on both sides of the treadmill are useful if a dog tends to step off to the side. Other useful features include variable speed control, a timer, and the ability to change the incline of the surface. Treadmills are very useful for patterning gait and encouraging initial weight-bearing following surgery. When the dog stands with the foot carried near the ground, it will generally begin to weight-bear when it is walked on a treadmill. It is important that the treadmill does not face toward a wall; rather, it should face toward a hallway or the middle of a room to encourage unimpeded walking. One person standing in front of the dog with words of encouragement or treats, and one person straddling the dog behind, are helpful in the early training stages to keep the dog walking straight. Walking on a treadmill for the first time is a new and sometimes awkward experience. Animals are not used to the ground moving under them, so when they walk on a moving belt, proprioception, coordination, and balance are challenged. The ground moving underneath the dog often encourages a dog which is nonweight-bearing on a limb as a result of an orthopedic condition to begin using the limb. In many instances, the animal will continue to use the limb even after the treadmill session is over. For patients with neurological conditions, the therapsist may stand beside a dog and manually advance a foot during the normal gait sequence to encourage gait reeducation. Treadmills may be useful during the initiation of rehabilitation programs for conditions in which extension of the hip or stifle are painful, such as hip dysplasia or post-operative recovery from cranial cruciate ligament surgery. Normally, patients are reluctant to perform activities such as climbing stairs, because extension of these joints is painful. Treadmill walking is less painful in some patients because the belt provides assistance with hip and stifle extension because the belt helps to pull the rear limb back. Therefore, there is less need for active contraction of the gluteal and quadriceps muscles for joint extension because the treadmill helps to pull the limb into an extended position with less muscle contraction than is needed to walk on land. The treadmill may be angled up or down to reduce or increase the forces placed on the forelimbs or hind limbs. A syringe cap placed on the bottom of the contralateral, unaffected foot pad often encourages weightbearing in patients that are reluctant to place weight on a limb. A sling may be used to support a paraparetic animal. To add resistance to limbs during treadmill activity to aid with muscle strengthening, an elastic band may be used to provide resistance to specific muscle groups. The band is secured to the involved extremity and the handler provides stability on the opposite end. For example, the band may be tied around the forearm with the line of pull from the rear, providing resistance and strengthening of the elbow flexors and shoulder extensors during the swing phase of gait. Assisted active advancement of a limb during the swing phase of gait can also be performed by using an elastic band. An animal with conscious proprioceptive deficits or muscle weakness which is unable to lift its foot off the ground during the swing phase of gait can be assisted using an elastic band. After attaching one end of the elastic band to the foot, the other end is secured to the body with the direction of pull designed to assist active advancement of the limb during gait. The handler may also manually place the foot as the animal walks on the treadmill. Dancing and Wheelbarrowing Dancing is a technique to increase weightbearing and force on the rear limbs, while also challenging proprioception, coordination and balance. When the dog's front legs are lifted off the ground, this shifts the weight to the hind limbs, and also promotes stifle, hock, and hip extension. The higher the dog is elevated off the ground, the more extension is required in the rear limb joints. It is important for the therapist or veterinarian to evaluate available range of motion in the rear limb joints before attempting this exercise to identify any potential limitations that may prevent the animal from safely performing the exercise. When a dog is using its affected limb consistently at a walk with minimal lameness, dancing may begin. Muzzle dogs prior to exercise. The forelimbs are lifted off the ground, allowing the patient to bear weight only on the hind limbs. Dogs with normal proprioception will naturally move the rear limbs as the handler moves and the animal "dances"backward and forward. Some dogs may resist dancing forward if the handler stands in front of the dog; dogs may plant their hind limbs and stretch out as the handler moves until the forelimbs reach the ground. In this situation, the handler should stand behind the dog, placing their arms under the axillary region to support the dog, and walk forward. The height that the dog is elevated off the ground depends on the amount of stress the animal is able to comfortably handle on the hind limbs. Dogs may be elevated as high as possible and also dance up and down inclines or hills to place additional stress on the hind limbs. Wheelbarrowing is an exercise similar to dancing, except that the forelimbs are targeted. This exercise encourages increased use of the forelimbs, and challenges proprioception, coordination, and balance. The dog's orthopedic condition must be adequately stable to handle the stresses of this exercise. The handler should place a muzzle on the dog. To perform the wheelbarrow exercise, the handler places the hands under the caudal abdomen and lifts the rear limbs of the dog off the ground, and the dog is moved forward. Dogs with normal proprioception will move the forelimbs so they do not fall. Some dogs may require sling support if they are weak. Dogs may be wheelbarrowed up and down inclines for greater muscle strengthening. Theoretically, the higher the animal is lifted, the greater the forces placed on the forelimbs. However, the increase in weightbearing may not be as great as anticipated because the stride length is much shorter when the animal is wheelbarrowed from a height. The shortened stride results in less force placed on the limbs while wheelbarrowing as compared with walking or trotting at a faster speed. Jogging Jogging may be initiated in cases with stable surgical repairs when the dog is walking on the limb with minimal lameness and pain. Begin slowly, jogging 0.5-3 minutes one to three times daily, and work up to 20 minutes two to three times daily. Be certain that lameness is not worse after jogging. Sit-to-Stand Exercises Sit-to-stand exercises help strengthen hip and stifle extensor muscles and improve active range of motion. The act of sitting, then standing up, requires muscle strength of the quadriceps, hamstring, and gastrocnemius muscle groups. Some training will be necessary, and low calorie treats may be offered as a training aid to provide motivation to perform the movement. It is important to perform these exercises correctly. Attention should be paid to sitting and standing straight, with no leaning to one side, and the joints of both rear limbs should be symmetrically flexed so that the dog sits squarely on its haunches. While on the leash, after a sufficient warm-up period of walking, the handler asks the dog to sit squarely for a few seconds and then asks the dog to stand, take a few steps forward, and then again sit. The sit-to-stands may be repeated a number of times before allowing the dog rest. It may be easier in some cases to back the dog into a corner, with the affected limb next to a wall so that the dog cannot slide the limb out while rising or sitting. Start with 5 to10 repetitions once or twice daily, and work up to 15 repetitions three to four times daily. This exercise may be particularly beneficial for those dogs with osteoarthritis of the hips. These patients are generally painful when the hip joints are extended. In addition, there may be atrophy of the gluteal muscles. The sit-to-stand exercise allows active contraction of the gluteal muscles, but the hip joint is not generally extended to the point which results in pain. This allows strengthening without creating undue pain. Of course, each patient must be assessed to be certain that sit-to-stands are not too stressful or painful for an individual. Down-to-Stand Exercises A variant of the sit-to-stand exercise is the down-to-stand. With this exercise, the dog is allowed to rise from a ventrally recumbent position to a standing position. It is important to have the dog rise symmetrically and push off equally with all four limbs. This exercise may require some additional time and training to perform correctly. Cavaletti Rails Cavaletti rails are poles which are spaced apart on the ground at a low height. Cavaletti rails may be used to encourage greater active range of motion and lengthened strides in all limbs. They may also be used to challenge proprioception, balance and coordination in animals returning to function following neurological impairment. An alternative to cavaletti rails is to use a ladder and allow the rungs of the ladder to act as the low rails. Although ladders are readily available in most households, they have limited flexibility to change the distance between the rungs and the height that the animal steps over the rungs. This exercise can be beneficial for either orthopedic or neurological patients in need of improved voluntary motor control and accuracy in placement of the limbs. One or more poles may be used and should be spaced at appropriate distances apart, determined by the dog's natural stride length. After the animal becomes accustomed to the task, the handler can further challenge the dog by making simple modifications such as adding more poles, increasing the height of all the poles to encourage greater active flexion and extension of joints, and altering the heights of alternating poles to encourage dogs to negotiate different situations. Begin with walking and progress to trotting. Walking in Tall Grass, Sand, or Snow Walking a dog through a field of tall grass enhances muscle strengthening and endurance because of the resistance provided by the grass, as well as coordination to navigate varying terrain. In addition, dogs have a tendency to flex their joints to a greater extent as they negotiate through the grass. Some caution should be used in dogs with allergies which may be aggravated in such conditions, and in dogs with conjunctivitis which might also be exacerbated. Walking in deep sand or snow provides resistance to limb movement during walking and jogging, and strengthens the flexor muscles which must contract more to advance the limbs. Exercising in sand and snow minimizes concussive forces placed on arthritic joints, while allowing strengthening of supporting periarticular muscles. Standing in sand may also be beneficial to dogs in rehabilitation following neurologic conditions. Pole weaving Weaving between vertical poles helps to promote side bending of the dog's trunk and also challenges proprioceptive functioning and strengthening of limb abductor and adductor muscles. The distance between poles should be adjusted so that sufficient side bending results; in general, the distance between poles should be slightly less than the body length of the dog. In addition, the handler must lead the animal so that the head, neck, and body actually flex as the poles are negotiated. Pulling or Carrying Weight A variety of harnesses are available for dogs to attach to carts or sleds for pulling weight. The harness should be well padded and comfortable. Pulling a cart with a large wheel diameter is easier than pulling a sled which slides along the ground. The position of the head and neck are important in determining whether a dog pulls the weight forward with the forelimbs or the hind limbs. If the dog carries its head and neck low to the ground, it is likely pulling with the forelimbs. A dog with the head and neck held high will shift some of the weight caudally and tend to use the hind limbs to drive the body forward. A variety of sleds and carts are commercially available. In all cases, the harness should be adjustable and properly fit the animal and cart or sled to avoid abnormal pressure where the harness contacts the animal; a poorly fitted rig may result in pressure sores and alter the manner in which the dog pulls the weight. Dogs may also wear leg weights. Leg weights may be fashioned from lead strips or commercially available leg weights for people may be used. In general, ½ pound leg weights may be used on dogs that weigh 10 to 20 lbs, 1 lb weights may be used on dogs weighing 20 to 40 lbs, 1½ lb weights for 40 to 60 lb dogs, and 2 lb weights may be used for dogs weighing greater than 60 lbs. Caution should be used when first applying the weights because some dogs may shake the limb or have exaggerated limb motion because of the altered sensation. It is possible that injury may occur, so it is important to gradually introduce the weight to allow a period of accommodation. Some leg weights designed for people may not fit properly. Many of these are fully filled with sand, and when the weight is applied to the thinner dog limb, the fastening straps may not allow a snug fit of the weight which may result in the weight slipping off. Removal of some of the sand may solve this problem. Another factor to consider is location of the limb weight. Biomechanically, greater force is required to move a limb if the weight is located more distally on the limb. Likewise, a distally-placed limb weight may place additional torque on the joints, which may be undesirable if the animal is recovering from joint surgery. In this situation, placing the weight more proximally reduces the forces on the limb and joints. Dogs may also perform chronic "weight lifting" by wearing a canine backpack filled with weights. Weights may be loaded unequally or equally on both sides. Using weighted backpacks during down-to-stand or sit-to-stand exercises requires greater muscle force to rise to a standing position. Controlled Ball Playing Ball playing is a fun and effective form of therapeutic exercise which dogs and their owners enjoy. It also has the potential to cause damage to surgical repairs. Controlled activity is the key. The degree of activity depends on the surgical procedure performed, the condition of the tissues, and the stage of tissue healing. Ball playing should begin on a relatively short leash to avoid explosive activity in the early post-operative period. As the patient progresses, the dog graduates to ball playing in an enclosed area, such as a run. As the animal nears full return to function, off-leash activity may be performed in a large fenced field free of irregular surfaces. The main benefits of ball playing are to increase power, speed, and muscle strengthening. In most conditions, jumping should be avoided to reduce the risk of injury. Methods to Encourage Weightbearing A syringe cap or coin may be placed on the bottom of the contralateral uninjured foot and held in place with adhesive tape to encourage weightbearing on the affected limb. In many instances, weightbearing continues on the affected limb even after the item is removed from the good foot. Some dogs will build up a tolerance to the item; therefore, continuous application is not recommended. In some particularly difficult cases, a sling may be placed on the contralateral nonaffected limb to force the animal to bear weight on the affected limb. In our experience, this technique is less effective because many animals simply lay down and will not attempt to walk. Hemiwalking is sometimes useful to encourage weightbearing on a particular limb. This exercise is performed by elevating the ipsilateral fore and rear limbs off the ground and shifting the weight to the contralateral limbs. The animal must move the contralateral fore and rear limbs laterally to avoid losing balance and falling. Although generally more successful than placing a sling on a limb, some animals may still resist this activity and simply lay down. Other Techniques to Encourage Limb Use Some dogs and most cats provide special challenges when attempting to rehabilitate the animal after injury. Additional activities may encourage limb use. Many cats will readily chase a flashlight around a room. Caution should be used to have good footing, such as carpeting, and to move the light at a speed appropriate for that animal's stage of recovery. In addition, stretching may be employed by moving the light along a vertical surface, such as a wall. Some dogs and cats will also chase a laser pointer light. Many cats and dogs have been well-conditioned to the sound of a can opener or other audible cues such as a door opening to go for a walk. The animal may be placed in another room and the audible sound initiated. In many instances, the animal disregards a lame leg and ambulates to the sound. Most cats and some dogs will play with a toy such as a string or other object that they are used to "stalking" or chasing. Engaging the owner to identify some favorite playthings is important, because some animals will not react to toys in a strange environment, such as a clinic. It is equally important to instruct the owner regarding the length of playtime, how to use the toy to maximize the rehabilitation process, and limits of play to reduce the chance of fatigue and injury. Yet another technique that is sometimes useful to encourage limb use in difficult cases is to have a treat and encourage the animal to follow the treat while the owner holds it in front of the animal and moves about. This technique is also useful in animals which are stiff in the neck and other portions of the spine to encourage side bending. With the animal in a standing position, the treat may be moved from right to left and up and down to encourage mobility of the spine and surrounding muscles. This technique is contraindicated in those animals with an unstable spinal canal or those with unstable intervertebral disks. Aquatic Therapy Water has useful features for rehabilitation, including thermal effects, buoyancy, increased hydrostatic pressure, cohesion, and turbulence. The benefits of aquatic exercise are many. Heart rate and oxygen consumption are greater when doing exercises in water. Patients with poor balance can stand because buoyancy will help keep patients from falling. Patients unable to bear full weight on joints can walk, and patients with weak muscles can move body parts. There are many indications for aquatic therapy. Contraindications include cardiac or respiratory dysfunctions, decreased thermal sensation, severe peripheral vascular disease, danger of hemorrhage, infections, incontinence, and diarrhea. Aquatic exercise should be initiated only after incisions are sealed and there is no drainage. Activity must be supervised at all times. Also, some dogs and most cats may thrash and hurt themselves. If possible, training should begin in water prior to surgery. Warm water (85-90 F) should generally be used. Dogs may be lowered into a pool or tub using a Hoyer-type lift. In the early phases of rehabilitation, the therapist should provide support to the patient or canine life preservers may be applied. Many patients will be in poor cardiovascular condition, and 2-3 minutes of aquatic therapy may tire some patients. Over the course of 10-14 days, therapy may increase to 10-15 minutes per session. Water wings or styrofoam balls attached to a limb may increase resistance and work that the limb must perform during aquatic therapy. Whirlpools, swimming pools, bathtubs, sinks, lakes and streams, and underwater treadmills may be used for aquatic therapy. Whirlpool tanks are stainless steel, plastic, or fiberglass tanks with an agitator. They must be thoroughly cleaned between patients. Large, deep tanks allow swimming by all but the largest dogs. Hubbard tanks are large keyhole-shaped tanks that allow a larger area for walking or swimming, but require a larger volume of water. Therapeutic pools and swimming pools are larger and suitable for all size dogs. There must be a mechanism to get the dog into the pool, such as a ramp, lift, etc. Some dogs, especially early in the rehabilitation period, may use either the front or rear limbs to swim and only float the injured limb. In these situations, an underwater treadmill is very useful to encourage active limb use, yet have the buoyancy effects of the water. Pools should be equipped with a chlorinator, heater, and heater heavy-duty filters. Underwater treadmills are a relatively recent addition to aquatic therapy. Depending on the water height, patients may walk partially submerged or may swim. Progression of Exercises Many variables must be considered in the design of a therapeutic exercise program, including the type and severity of the condition, the stability of any surgical repairs, the number of involved limbs and joints, the size of the animal, the pre-existing physical condition of the patient, the available facilities, the skill and experience of the therapist, and whether the exercises will be administered by a professional, the owner, or a combination of the owner and a professional. Unfortunately, it is impossible to have a single protocol for each specific condition. Some basic guidelines may be applied, however. The goal of any therapeutic exercise program should be to restore the animal to as full and active use as possible. The goal may need to be periodically adjusted if the patient progressing to a greater or lesser degree than expected. The initial goal should be to have the patient bear its full weight while standing. The next step should be assisted active ambulation. Proprioceptive training should occur concurrently with active ambulation, with the goal to have unassisted active ambulation while maintaining balance. As the animal nears return to housepet function, strategies should be developed to encourage increased weight-bearing and muscle mass. It is very important to perform the exercises correctly and to maintain a consistent level of activity on a daily or every other day basis. In most cases, several short sessions per day will be more effective than a single long session early in the recovery period. Overdoing activity on the weekends with relatively little activity during the rest of the week will likely be detrimental to the animal's recovery; regular, daily activity will avoid the "weekend warrior" syndrome. If pain or lameness increase during or several hours after stepping up an activity, the level of activity should be reduced by 50% for 3-7 days. If the lameness and pain resolve, the activity may be slowly increased back to the pre-step up activity level over 3 to 5 days, with careful observation to be certain that the activity is not increased too aggressively or rapidly. The rate of subsequent step-up activity should be half of what it originally was to avoid a recurrent episode of exacerbated of lameness and pain. It is also important to vary the routine for the animal's and the owners' sake to avoid boredom, and to allow incorporation of function-specific activities in the animal's home or work environment. During chronic management of the patient, weight control is extremely important. It is also important to continue to oversee the protocol and document improvement. Progress will occur at a slower rate during the chronic phase of recovery, but continued rehabilitation is just as important to achieve as full a return to activity as possible. Several medications may be appropriate for use in the chronic rehabilitation period, including nonsteroidal anti-inflammatory agents and chondroprotective agents. Caution should be used, however, to be certain that any analgesic medications do not mask pain and discomfort associated with the level of activity. They should facilitate rehabilitation and recovery rather than allow rehabilitation to progress faster than normal conditions and tissue healing should allow. When stepping up the level of an activity, it is recommended to withhold anti-inflammatory or pain medication the day of step-up, and for the day after stepping up the activity to be certain that there is no additional tissue damage. If pain or lameness increase, the level of activity should be reduced 50% for 1 week, then the activity is stepped up again at a slower rate. Therapeutic Ultrasound Therapeutic ultrasound (US) has been used to treat a vast assortment of conditions, and the effects of US can be divided into two domains, the thermal effects, and the non-thermal or biologic effects. Although hot packs are effective for superficial heating, deeper heating may be desired. The thermal effects of US on human tissues are well documented, and are used to decrease pain, reduce muscle spasm, and to increase the extensibility of collagen allowing tissues to be stretched more effectively. US penetrates up to 5 cm, and heats tissues to 40-450 C. Tissue temperature need to be raised 3-8° C to obtain the increases in tissue extensibility associated with heating. US is more readily absorbed in bone than in protein rich tissues such as the dermis and muscle, which in turn absorb more US than fat. Therapeutic US typically uses 1 or 3.3 MHz transducers with 2 or 5 cm transducer head sizes. 1 MHz US has been shown to have its greatest effects on tissue depths of 2.5 to 5.0 cm. 3.3 MHz US has been shown to have its greatest effects from 1.0 to 2.5 cm. The continuous mode is used for heating. In addition to heating tissues, US may also increase collagen deposition, wound closure, and wound breaking strength. Specific non-thermal or biologic effects of US that have been demonstrated include acceleration of the inflammatory phase with a quicker entry into the proliferative phase of repair, stimulation of fibroblast proliferation, and decreased pain. Other biologic effects include promotion of stronger and more elastic scar tissue due to an increase in collagen formation and change in collagen fiber pattern, and changes in membrane permeability which may speed the healing process. To perform US treatment, clip the hair and liberally apply US gel to the site. The choice of the coupling agent used for transmission of US has also been shown to be critical. Commercially prepared US gels offer the best transmission and thus the greatest degree of heating. The proper size transducer head, and proper frequency for the tissue depth are selected. Power settings are typically 1-1.5 watts/cm2. Most units have a timer that shuts off after treatment. The maximum treatment area should be no more than 4 times the diameter of the sound head, with a treatment time of 4 minutes for every sound head area within the targeted treatment area. Larger areas will not have effective tissue temperature increases. The US head is slowly moved over the treatment area in an overlapping circular or grid pattern. The sound head must be continuously moved to avoid "hot spots". Observe the animal for discomfort, such as pulling the limb away or whining, which may indicate overheating, especially over joints or bony surfaces. The time of tissue temperature elevation is relatively short, so stretching and range of motion exercises should be performed either during the latter half of the treatment or immediately after to take full advantage of tissue extensibility. The use of US for heating of both superficial and deep connective tissues holds great promise in the field of veterinary rehabilitation. It should be pointed out that unless US is used efficaciously it may cause tissue damage such as dermal necrosis or overheating of the tissues leading to an inflammatory response. Neuromuscular Electrical Stimulation Electrical stimulation (ES) is a commonly used modality in physical therapy, and has proven to be effective for many purposes including increasing range of motion (ROM), increasing muscle strength, muscle re-education, correction of structural abnormality, improving muscle tone, enhancing function, pain control, accelerating wound healing, edema reduction, and muscle spasm reduction. Terminology relating to ES has been ambiguous, and has thus been standardized to avoid confusion. ES refers to any type of electrical stimulator and is the broadest term used. The use of ES to stimulate a peripheral nerve and to cause either a sensory, motor, or noxious response is termed neuromuscular electrical stimulation (NMES). This is the most commonly used type of ES, and includes all applications of ES for strengthening, except in cases of denervated muscle. The use of ES to excite denervated muscle directly, such as in individuals with spinal cord injuries is called electrical muscle stimulation (EMS). The term TENS, or transcutaneous electrical nerve stimulation has been erroneously used, and as such is commonly thought of as a portable stimulator for pain control. Although one of the primary clinical uses of ES is indeed pain management, In actuality, almost all ES units are TENS units, in that they apply a transcutaneous current. There are certain conditions in which ES should not be utilized, or should be used with caution, including high intensity stimulation directly over the heart or in animals with pacemakers, animals with seizure disorders, over analgesic areas, over infected areas or neoplasms, over the carotid sinus, or any time active motion is contraindicated. Types of Current Stimulators can be broadly divided into three categories - continuous direct current (galvanic) that is only used for iontophoresis, pulsed alternating current (AC), and pulsed direct current (DC). DC units are commonly referred to as monophasic, and AC units as biphasic. Research supports the use of AC units for muscle strengthening due primarily to comfort, however pulsed DC units may also be used. Another type of current used for NMES is a medium frequency polyphasic current sometimes referred to as "Russian Stimulation." Types of Stimulators There are literally hundreds of ES units on the market. Many claims of superiority of one machine over another are unfounded. There are stimulators that are better suited for a particular use, i.e., strengthening, pain reduction, edema reduction. Adequate knowledge of the devices and their capabilities is needed to make an informed decision about purchase. Electrodes There are many types of surface electrodes on the market. The main criteria in choosing electrodes are that they: 1) should be flexible enough to conform to the tissue, 2) may be trimmed to a specific size, 3) have a low resistance (typically <100 ohms), 4) are highly conductive, 5) may be used many times, and 6) are inexpensive. There are many types of electrodes on the market, some are good for only a few uses, and some may be used 100 or more times (carbon-impregnated silicon rubber electrodes). Electrodes require a medium to transmit current. Commonly used media include gels, sponges or paper towels. Sponges and paper towels tend to dry out and re-wetting is necessary every 30 minutes. Conductive performance of any electrode will decrease over time. Electrodes should be of the appropriate size to stimulate the desired muscle without stimulating unwanted muscles in close proximity. The smaller the electrode, the higher the current density, and the more painful the stimulus may be. Electrode Placement For strengthening, one or more electrodes should be placed as close as possible to the motor point of the muscle being stimulated (the area where the motor nerve enters the muscle). This will provide the best contraction with the least amount of current, and thus minimize discomfort. TYPICAL PARAMETERS AVAILABLE IN NMES DEVICES 1 Frequency - The rate of oscillation in cycles per second, expressed as pulses/sec (pps) or Hertz (Hz). Often labeled as pulse rate or pulses/sec, or frequency on stimulators 2 Phase/Pulse duration - The duration of a phase or a pulse, usually measured in microseconds. 3 Amplitude - the current value in a monophasic pulse or for any single phase of a biphasic pulse 4 Waveform - The shape of the visual representation of pulsed current on a current/time plot or voltage/time plot. Can be symmetrical, asymmetrical, balanced, unbalanced, biphasic, monophasic, polyphasic, etc. 5 On/off time - amount of time the stimulator is delivering current in seconds 6 Ramp - the time from the leading edge of the phase to increase in amplitude from the zero current baseline to peak amplitude of one phase, or from peak amplitude back to baseline 7 Polarity - electrode may be either the anode or cathode Muscle Fiber Recruitment ES recruits fast twitch fibers first, then slow twitch fibers, which is the reverse of a volitional contraction. An increase in pulse duration increases recruitment of smaller diameter motor units at the same depth. Increasing pulse duration too much may stimulate undesirable fibers (small diameter painful fibers). Increasing either the amplitude or the pulse duration affects the strength of contraction due to recruitment of additional fibers. Increasing the frequency results in the existing motor units firing at a faster rate and will increase the strength of contraction, but it will also cause fatigue. Optimal frequency gives an optimal physiological response while minimizing fatigue. Current Parameters for Strengthening Frequency generally between 25-50 Hz (these have been shown in humans to produce tetanic contractions while minimizing fatigue) Waveforms - many shapes on the market; symmetrical biphasic may be the best Pulse or phase duration between 150-250 microseconds Ramp (rise and decay time) 2-4 seconds up to increase comfort, 1 second own On/off time 1:4 or 1:5 ratio. 10 seconds on, 40 or 50 seconds off is commonly used Animal Reaction/safety Precautions should be taken to avoid injury to the handler and animal. A muzzle should be applied and the animal placed in lateral recumbency during the initial treatment. In some cases, tranquilization may be necessary if the patient is anxious. We recommend that treatment only is given under the supervision of trained personnel. Preparation/electrode Placement The hair over the area which ES will be applied must be clipped to lower impedance. The skin should be cleaned with alcohol prior to treatment. It will be necessary to locate the motor point (the area where the motor nerve enters the muscle), so that an adequate contraction is obtained, with as low a current as possible to minimize discomfort. During the first session, gel may be applied to the skin. The electrode is then applied to the general location of the motor point. With the unit on, the electrode may be moved around until a good contraction is achieved. Setting the frequency at 1 Hz will help in motor point determination because the twitch contraction will be more discrete and will get stronger as the electrode moves closer to the motor point. Remember to adjust the frequency to the desired setting (25-50 Hz) before starting treatment. An indelible marking pen is then used to draw a circle around the electrode. This will allow the electrode to be placed in the same area during subsequent treatments. Treatment 15-20 minutes, 3-7 times/week Consider co-contraction if no joint movement is desired Possible Uses Post-operatively (first 2-4 weeks) Muscle atrophy (even long standing) Selective strengthening of a muscle group or groups Extracorporeal Shock Wave Treatment Extracorporeal shock wave treatment has been used in horses for treatment of tendinitis and ligament desmitis, and has been FDA approved for the treatment of plantar faciitis and lateral epicondylitis in humans. We have recently completed a study of osteoarthritis in dogs with moderate to severe osteoarthritis of the elbow or hip joint and found a significant increase in comfortable range of joint motion, as well as a significant increase in forces placed on the limb. Most of the improvement occurred after the first treatment, although further improvement was noted after a second treatment three weeks later. Results appear to be similar in magnitude to non-steroidal anti-inflammatory agents and last for up to one year. Further research is needed to define the role of this modality in the management of osteoarthritis in dogs. Assessing Outcomes Assessing the outcome of treatments, including physical rehabilitation, is essential to determine how an animal is progressing and to determine the effectiveness of treatment protocols. Review of outcome data and evaluation of protocols are necessary so that changes may be initiated to improve outcomes. Assessments should consist of objective data whenever possible because owners and veterinarians often believe a patient is doing better than what the data suggest. In addition, documentation of progress is important to provide incentive for owners to continue rehabilitation and to justify continued treatment. Several measurements are important for assessing outcomes, including return to function, the ability to perform functional activities of daily living, gait analysis, joint function, body composition, muscle mass and strength, and impressions of owners and veterinarians. Measuring Outcomes There are many possible outcome measures in assessing canine patients. The easiest and perhaps the most valuable outcome measure is the patients return to function. Different patients and owners may have various expectations for return to function. For some have, it may be very important for them to return to vigorous work, such as a working police dog or a racing animal. For others, return to function may mean return to life as a house pet or other less vigorous activities. For some patients, return to function is not a realistic goal. For example, the dachshund with loss of the pain sensation to its fore limbs or an animal with a serious vertebral body fracture may have little if any chance of returning to normal function. In cases such as these, return of functional activities of daily living are more realistic goals. Parameters which may be assessed to determine the degree of treatment success include gait evaluation, joint function, body composition, muscle mass and function, and the impressions of the owners and veterinarians. Joint Motion Joint motion may be evaluated using objective and subjective assessments. The quantity of joint flexion and extension motion is measured using a goniometer. Normal angles of maximum flexion and extension have been reported. Measuring maximum angles may involve some discomfort. An animal experiencing discomfort is unlikely to use the limb at those angles while ambulating. Therefore, measuring the comfortable range of motion may be more clinically applicable. To measure the comfortable range of motion, the joint is slowly flexed until the first indication of discomfort is noted. The joint is then slowly extended until the first indication of discomfort is noted. These angles are recorded. The quality of joint motion is more subjective and involves the assessment of joint biomechanics, crepitus, and pain during motion The quality of joint motion may indicate abnormalities such as restriction by fibrous tissue, joint capsule, bone, or cartilage. Crepitus is often associated with surface irregularities in articular cartilage or periarticular changes, such as occur in osteoarthritis. Other sensations such as cracking, snapping, or popping may indicate abnormalities, such as a torn meniscus. Clinical Assessment of Muscle Mass Regaining muscle mass and strength following injury are important to help improve function, and prevent further injury. Muscle mass indicates limb use and is associated with muscle strength. There is significant correlation of thigh circumference measurements with muscle mass, validating the use of thigh circumference measurements as a clinical tool to assess muscle mass. We have also found thigh circumference measurements to be adequately sensitive in documenting muscle atrophy and hypertrophy. Acceptable results depend on using standard, repeatable methods of measuring limb circumference. A measuring tape with a spring tension device is useful to improve consistent placement of tension on the tape when making measurements. We currently measure thigh circumference by first measuring the distance from the greater trochanter to the distal lateral fabella. The stifle should be fully extended, which causes the muscle bellies to elongate. Girth measurements are then obtained at 70% of the measured thigh length. We have measured thigh circumference before and after clipping hair, and have found an average difference of 3-4 mm when performing measurements on clipped vs. unclipped short-haired dogs. Dogs with longer hair will likely have more significant differences, and this needs to be accounted for. Sedation resulted in a slight decrease in circumference compared to a fully aroused state although the differences were not significant. Measurements taken with the stifle in full flexion and in a functional standing position are greater than measurements taken with the stifle in full extension. Follow up measurements should be taken in the same position for the most accurate results. With a brief training session, we have demonstrated high inter-tester reliability of measurements with the agreement between testers within 3.5% of each other. Return to Function Return to function is perhaps the best indication of a successful outcome following treatment. The desired level of function depends on the intended use of the patient, which varies from a highly trained working dog to a house pet. Some outcomes are relatively easy to quantify, such as being able to perform a particular task in the case of a working dog. Others are more nebulous, such as a return to acceptable house pet function. Regardless of the desired outcome, reasonable expectations must be set based on the severity of the condition being treated, and this must be conveyed to the owner. For example, it is unreasonable to expect an elderly arthritic dog to return to competitive coursing, but it may be reasonable to expect the dog to be able to play ball for short periods of time. Expectations may need to be altered if the response to treatment is better or worse than expected. Functional scoring systems for specific injuries may be useful, such as a functional stifle score. The optimal method to measure the degree of functional disability is unknown in dogs. A useful system in dogs likely should incorporate limb use, lameness, stance, pain, muscle atrophy, range of motion, joint effusion, drawer motion, and functional activities to evaluate limb function following cranial cruciate ligament surgery. Other functional tests that have been used in humans may be applied to dogs, with modification. Functional Activities of Daily Living This category is more applicable to humans receiving physical therapy, but may be applied to dogs with the idea that the patient should regain the ability to do things for themselves with minimal assistance. Some conditions are so serious that complete recovery cannot be expected. In these situations, the owner must be informed of a reasonable expected outcome. The rehabilitation goals should be realistic and concentrate on performing basic functions, such as eating and drinking, changing body positions without assistance, rising from a sitting position, and walking outside to urinate and defecate. For a paraplegic dog, this may mean that the patient is able to get up to go outside and eliminate. For an older arthritic patient, this may mean that the patient has the ability to climb a few stairs to get in and out of the house. For others with specific duties or tasks to perform, this may mean the ability to perform those expected tasks on a daily basis. Progress may be slow, but should be recorded. Gait Assessment There are qualitative and quantitative methods of evaluating the dogs gait. Qualitative assessment of gait may include observations and assessment note the flight of limbs during gait. The length of stride, presence or absence of circumduction, flexion or decreased motion of joints, and other factors may be assessed. In general, therapy patients are evaluated at the walk, trot, pace, or faster gaits. For patients in the early postoperative period or those with serious disabilities, it may be possible to assess the patient only at a walk. The trot is the most commonly used gait to evaluate the therapy patient. It is important to differentiate the trot from the pace. Approximately five percent of dogs will have the pace as their natural intermediate gait. More commonly, dogs which pays to sell to limit the degree of flexion and extension of joints. Many owners and veterinarians report that the dog trots very stiffly. In fact, the dog may not be trotting but only pacing. Because the pace is a lateral two beat gait, the dog is able to roll its body from left to right and right to left with minimal need to flex joints. It is difficult to evaluate dogs at faster gaits, but one effective method of gait assessment in a racing animal is the time to complete the race. Weight-Bearing at a Stance Evaluation of a dog's stance gives information regarding willingness to place complete weight on an affected limb. Many dogs may have no visible or only very mild lameness at a walk or trot, but will not bear equal weight on the limbs when standing. Weight-bearing at a stance may be assessed by observing the placement of a foot in relation to the contralateral front or rear foot. In severe cases, the dog may hold the foot completely or partially off the ground. More commonly, the dog places a moderate amount of weight on the foot, but not complete weight. The toes may point out and when the limb is gently pushed forward, it may be moved more easily than the contralateral limb when it is gently pushed. Alternatively, the evaluator may place both hands under the fore or rear feet with the palm facing the pads, and the relative amount of weight-bearing may be assessed. Weight-bearing at a stance may be incorporated into global lameness scores. An inexpensive method of acquiring more quantitative information regarding weight-bearing at a stance is to have a dogs stand with each limb on common household scales. It is important to be certain that the dog is standing squarely in a standard position. Dogs should also undergo a period of acclimation to the scales so that data collection is valid. Scales should periodically be calibrated to standard weights to be certain that accurate weights are recorded. Lameness Scores Lameness scores are a semi quantitative method of gait assessment and may be the only means of comparing an animals improvement during the course of treatment. It is important to have separate lameness scores for the walk and the trot. Some animals will appear to be relatively sound at a walk, but may have mild to moderate lameness at a trot. Scoring systems which combine features of both the walk and the trot may be confusing to a person performing the evaluation. In addition, it is beneficial to have separate lameness scores for animals which are just beginning a postoperative therapy program as compared to those who have been in a rehabilitation program for some time, or those that are being treated for chronic conditions. During the early postoperative period, it is expected that in animal will be quite lame. However, it is important that the animal begin to use the limb consistently with nearly every stride. With more conditions, it is expected that in animal will use the limb consistently trained each stride, but it is more important to quantify the degree of lameness that the animal has to assess the outcome of treatments. Kinetic (Forceplate) Analysis of Gait Kinetic evaluation of gait involves the measurement of ground reaction forces with a force plate or platform. It is an objective, repeatable measure of weight-bearing on limbs when proper technique is used for data collection. Lameness may be compared over a period of time without relying on memory of previous assessments because data may be stored on a computer. Although measurement of ground reaction forces is a reliable and well-accepted method of determining the degree of weight-bearing on the limbs, it is an artificial situation and some dogs may display different clinical signs in a home environment. Force platform systems are available at many veterinary colleges and some private practices. It is important that appropriate software for quadruped animals be used. The force plate is either mounted on a platform or embedded in the floor so that it is even with the surface. A runway of adequate length is essential. Most systems have timer lights that are triggered as the handler and dog approach and cross the force plate to allow the calculation of mean velocity and acceleration. Control of velocity and acceleration within appropriate parameters is essential for repeatable data collection, because these greatly affect the force placed on each limb. The force plate is connected to a computer which calculates ground reaction forces. The most useful forces measured are the peak vertical force (ZPeak) and vertical impulse (ZImpulse). Other forces that may be useful are the peak braking (YA Peak) and propulsion (YB Peak) forces and braking (YA Impulse) and propulsion (YB Impulse) impulses. Medial-lateral forces (XPeak) and impulse (Ximpulse) are likely too small and variable to be clinically useful. Forces may be measured during stance, walking, or trotting. In general, dogs bear 30% of their body weight on each front limb and 20% on each rear limb while in a standing position with the limbs placed squarely under the body. Walking at a velocity of 0.7-1.0 m/sec results in forces equivalent to 60% of body weight on each forelimb and 40% on each rear limb in a medium to large dog. Increasing the velocity to a trot of 1.7-2.0 m/sec results in weightbearing of 100-120% of body weight on each forelimb and 65-70% of body weight on each rearlimb in a similar-sized dog. Reduced weightbearing on an individual limb may result in mild weight shifts to the other limbs. Kinematic (Motion) Analysis of Gait Kinematic or motion analysis of gait is a powerful tool which may be used to measure flexion and extension angles of joints during gait, stride length, and other parameter of stride. It is usually combined with kinetic gait analysis. There is limited availability of three dimensional kinematic gait analysis because the necessary equipment is sophisticated and expensive. Two dimensional systems are less expensive, but the data has limited usefulness because joints rotate and limbs circumduct during gait. Attention to detail is critical for kinematic gait analysis. Most systems use a number of reflective devices which are attached to the dogs at very specific anatomic points to allow repeatable data collection at different times. Motion of the markers in relation to the joints is determined with a series of cameras interfaced with a computer. Software for quadruped animals allows reconstruction of a walking "stick figure" on the computer screen. The software is then used to calculate a number of measurements, including flexion and extension angles of joints during gait, angular velocity of joints, and stride length and frequency. Noninvasive, computer-assisted, three-dimensional kinematic gait analysis was used in one study to describe lameness in a chronic model of cranial cruciate ligament rupture in dogs. Dynamic flexion and extension angles and angular velocities were calculated for the hip, stifle, and hock joints. Distance and temporal variables were also determined. Mean flexion extension curves were developed for all joints and the changes in movement that occurred over time after cruciate rupture were compared. Each joint had a characteristic pattern of flexion and extension movement that changed with cruciate rupture. The stifle joint angle was more flexed throughout stance and early swing phase of stride and failed to extend in late stance. Angular velocity of the stifle joint was damped throughout stance phase, with extension velocity almost negligible. The hip and hock joint angles, in contrast to the stifle joint angle, were extended more during stance phase. Stride length and frequency also varied significantly after cruciate rupture. A change in the pattern of joint movement appeared to occur in which the hip and hock joints compensated for the dysfunction of the stifle joint. Knowledge of kinematic parameters may allow more effective rehabilitation of patients following surgery or those with chronic conditions. In particular, changes which are noted during the course of treatment may allow for stepping up the level of activity, or more importantly, may signal changes which occur in other joints as a result of fatigue or overuse. Knowledge of these data may help prevent injuries to other joints or limbs. Pain Assessment Assessment of pain and discomfort are important in the physical rehabilitation of animals. Excessive discomfort may prevent or slow progress during treatment, but objective measurement of pain is difficult in animals because they do not verbalize the level of pain that they may be experiencing. Therefore, pain assessment scores are generally used to evaluate behaviors which are believed to be associated with pain and discomfort. In addition, ordinal or visual analog scales are sometimes used in which owners are asked how painful they believe their pet is. Some physiologic parameters, such as heart rate, respiratory rate, and blood pressure, have been used to evaluate pain in the acute post-operative period, but these are generally not as useful for assessing pain in chronic conditions. Painful behavior in dogs may be indicated by whining, crying, or other forms of vocalizing when the animal moves or the affected body part is manipulated. Holding an affected limb in a tightly flexed or guarded position is frequently noticed after surgery. Animals may be particularly resentful to palpation and manipulation of the area. Painful behavior may also be exemplified by laying quietly in the back of a run or in the corner of a room with little desire to rise and move about. This may be a protective mechanism to avoid further injury and pain from moving about. The degree of pain in these patients is frequently underestimated because of their quiet nature. Impressions of Owners and Veterinarians Dogs and cats have different personalities and may respond very differently to various therapies. It is important for individuals who best know the patient to evaluate their progress. For example, owners are often very aware of subtle changes in their pet's behavior. Although it is somewhat difficult to quantify these changes, these subjective findings often provide the therapist with important information regarding patient progress. If possible, the changes should be as objective as possible, such as recording the amount of time a pet spends playing rather than resting, measuring the distance that an animal is able to walk before needing to rest, or evaluating the length of time a neurologic patient is able to stand unassisted. Owners should keep a log of daily activities to further define the progress of the patient at home. This may also provide incentive for owners to continue a home rehabilitation program if they can see the progress that is made from week to week and month to month. Poor compliance is a common reason for failure of a patient to progress. Regularly checking the log gives the veterinarian and owner an opportunity to evaluate the patient's progress, as well as make alterations to the rehabilitation program that account for an owner's ability to provide continued home care. In addition, videotaping the patient's activity on a regular schedule will allow comparisons to be made over relatively long periods of time. The Business of Small Animal Physical Rehabilitation While there are many factors that have contributed to the recent interest and popularity of veterinary rehabilitation, awareness of the merits of physical rehabilitation by the pet-owning public and their demand for more of these services has largely driven the development of this field. The evolution of the status of pets in the household, and the growing demand by pet owners for advanced care has promoted the expansion of veterinary services. The public realizes the value of optimal medical services for human beings, and expects similar if not better care for their pets. Small animal physical rehabilitation is an exciting new developing field of veterinary medicine. Interestingly, humans have served as models for animal rehabilitation, and the value and efficacy of physical therapy is well documented in the medical literature for humans. Recent and ongoing veterinary research documents the benefits of small animal physical rehabilitation. It is now clear to those engaged in providing veterinary rehabilitation that historical post-operative and conservative management protocols are antiquated. The advent of incorporating physical rehabilitation into veterinary practice is the result of the pursuit of optimal animal care. The differences in clinical outcomes are exhibited by the patient, perceived by the owner, and progressively being recognized by the veterinary profession. The decision to engage in providing new services in practice follows a sound business evaluation. To determine if establishing a physical rehabilitation practice is feasible, a number of important factors should be considered, including a patient survey to establish a need for this service. The practice should determine the projected numbers of in-house and referred cases of musculoskeletal trauma, neurosurgical cases and other conditions for which rehabilitation may be indicated. At a minimum, a facility should have three to five patients per day to justify a full-time effort. The costs of the facility and equipment, including purchase, set-up, marketing and advertising costs must also be considered. Space is almost always a limiting factor in veterinary facilities. Whether existing space is available or additional space is generated through renovation or separate facility construction, a professional appearance is a must. To provide adequate rehabilitation services, a reception and waiting area, patient assessment area, treatment area including room for aquatic equipment, patient housing (particularly for in-house cases), an exercise area for outside therapeutic modalities and care, office space, storage, and client parking must be considered. Rehabilitation efforts may begin with very little equipment. Passive range of motion, massage, icing, heating, gait training, and many other therapeutic activities may all be accomplished with minimal expense. Ice packs, frozen packaged peas, water frozen in a Styrofoam cup, hot packs or a wet towel warmed in a microwave, and a therapeutic mat are basic equipment to get started. To perform a thorough evaluation, a tape measure and goniometer are useful. Safety equipment is also important to prevent damage to patients and handlers. Other equipment includes therapeutic ultrasound, neuromuscular electrical stimulation devices, ground treadmill, aquatic therapy, stairs, and an exercise area. Summary Beginning a rehabilitation program need not be elaborate or costly. Consideration should be given to the patient's needs, the owner's needs, and the therapist's needs. And while protocol development greatly depends on the available facilities and equipment, the willingness of the owners to help with rehabilitation, and the education level of the staff, some rehabilitation is better than none at all. Therapeutic exercises are undoubtedly the most important aspects of rehabilitation. Although a variety of techniques has been described, the ingenuity of the rehabilitation team, including the owner, will allow the development of other exercises that are specific to a patient's recovery. The keys to a successful therapeutic exercise program are to have site- and condition- specific exercises whenever possible, use a variety of exercises and techniques to keep the therapy team and patient from becoming bored, and to allow the animal to appropriately progress so that tissues are adequately challenged for strengthening, but not so rapidly as to result in complications and tissue damage.

© 2007 - Darryl L. Millis, MS, DVM, Diplomate ACVS, CCRP - All rights reserved