What Is Canine Rehabilitation?
Many people believe that canine rehabilitation consists mainly of laser therapy and an underwater treadmill. In addition, the notion that this field would be easy to grasp, with intuitive reasoning and little training, has led many to attempt to add rehabilitation to their veterinary practices. In reality, canine rehabilitation is an involved science that requires great skill, problem-solving abilities, and knowledge. Fancy equipment is a luxury but not necessary. The greatest asset for effective rehabilitation is an educated clinician with a pair of highly trained hands.
Physical therapists are rehabilitation specialists who have a defined role in the current medical model under the World Health Organization. All physical therapists entering the field today graduate from an accredited college or university program with a doctoral-level degree and must be licensed in their respective state in order to practice physical therapy (American Physical Therapy Association, 1999). In practice, physical therapists focus on the disablement model rather than the medical model of disease (World Health Organization, 1997). This allows the therapist to base interventions upon their impact on conditions affecting function rather than on a certain disease diagnosis. The disablement model focuses on the factors affecting an individual’s ability to perform daily tasks that are usual, customary, essential, and desirable to that being.
Application of the disablement model to canine rehabilitation emphasizes the functional status of a dog rather than a specific disease or pathology. The advantage to this approach is that animals differ in their presentation, regardless of having the same pathoanatomical diagnosis or medical condition. Physical therapists learn about pathophysiology of systems and diseases; however, the application of this knowledge is geared toward resolving the patient’s function and response to rehabilitation rather than the patient’s disease status. For example, a patient with a spinal disk herniation can present along a continuum of functional capacity from completely paralyzed to weakly ambulatory. The patient that is completely paralyzed has a much more involved functional status than the ambulatory patient despite the same diagnosis of IVDD at T12–13. The rehabilitation professional recognizes this during the examination and evaluation process. A physical therapy exam will encompass identifying functional limitations and disabilities and the related impairments contributing to those functional limitations (American Physical Therapy Association, 2010). The following is a list of terms used within the disablement model as defined by the World Health Organization, International Classification of Diseases (Levine et al., 2004):
In our example of two patients with disk herniation at T12–13, each has an active pathology, functional limitations, impairments, and disabilities (Table 5.1). The rehabilitation professional needs to perform an examination and evaluation to identify the:
Table 5.1 Two contrasting cases of disk herniation at T12–13.
| Patient 1 | Patient 2 | |
| Diagnosis | Disk herniation T12–13 | Disk herniation T12–13 |
| Disabilities | Unable to stand, unable to perform lie-to-stand transfers, unable to roll, unable to sit, dependent on bowel and bladder management | Unable to climb stairs without assistance from owner, unable to ambulate on uneven surfaces without loss of balance, unable to maintain squat position for >10 seconds for toileting |
| Functional limitation | Eats in lying position | Demonstrates unsteady gait on level surfaces and worsens on uneven or slippery terrain |
| Impairments | Flaccid muscle | Muscle weakness in the pelvic limbs, diminished proprioception, shortened hip flexor musculature |
| Goals | 1. Stand for 1 minute with minimum assistance 2. Transfers with minimum assistance 3. Owner to be able to express dog’s bowel and bladder two to four times per day 4. Maintain sit posture >30 seconds with minimum to moderate assistance | 1. Ambulate independently on all terrain >5 minutes without loss of balance or nail scraping 2. Independently maintain squat position for toileting 3. Ambulate up 3 steps independently to get into house |
| Interventions | Neuromuscular electrical stimulation (NMES), neurofacilitation techniques, protection for skin breakdown, simulated patterning of transfers, owner education, bowel/bladder elimination schedule, supported standing and weight shifting activities, laser therapy, passive range of motion (PROM), water work, massage, etc. | Massage, stretching, cavalettis, supported uneven terrain walking, resistance band work, sit to stands, therapy ball or peanut work, diagonal leg lift standing, underwater treadmill, sidestepping, side crunches, backward walking, rocker board, cookie stretches, etc. |
Interventions designed to improve basic functions would be performed with the paralyzed patient, while interventions to improve higher level functioning would be performed with the ambulatory patient.
Rehabilitation professionals must also understand comorbidities. For example, if the patient also has congestive heart failure, the therapist understands that the intensity of exercise must be modified.
Physical Therapy Principles and Terminology
Biomechanics
Mechanics is the study of forces and their effects (O’Sullivan & Schmitz, 1994). Biomechanics involves the application of these mechanical principles to human and animal bodies in movement and at rest, combining engineering with anatomy and physiology (TenBroek, 2005). The study of mechanics covers statics, the study of bodies while at rest, and dynamics or the study of moving bodies. Dynamics can be subdivided into kinematics and kinetics. Kinematics is the science of motion as it includes descriptions of motion without regard for the forces producing the motion. Kinetics is the study of the forces producing motion or maintaining equilibrium (Paris & Loubert, 1990).
Forces
Forces on biological tissues are defined as actions that result in tissue deformation causing a change in length, shape, or orientation. A force will result in acceleration, deceleration, or deformation of the tissues to which it is applied. Forces on biological tissues have a magnitude, direction, line of application, and point of application.
Types of Forces
Mechanical forces are applied to biological tissues by direct physical contact and are produced by external or internal influences. External forces are a result of contact or collision, such as the ground reaction force observed during the initial contact phase of gait when a limb first strikes the ground. Internal forces are generated by muscle contraction. Both forces will result in one of five types of loads:
- Compression
- Tension
- Torsion
- Shear
- Bending
Forces influencing loads are
- Electrical, mechanical, and electromagnetic
- Reaction
To understand the effects of these forces on biological tissues, an understanding of stress and strain relating to biological tissues is necessary. As discussed in Chapter 3, stress is defined as the resistance of internal forces acting against deformation caused by external forces. Strain is the measure of deformation that occurs as a result of external forces. Stresses are categorized as normal, shear, or combined. Normal stress occurs perpendicular to the plane of the cross section of a tissue. This stress consists of compression, bending, and tension. Shear stress occurs parallel to the plane of the cross section of the tissue when a load is applied perpendicular to fiber alignment. Torsion is also considered a type of shear stress. Combined stresses occur when bodies experience more than one type of stress simultaneously.
Compression loads in biological tissues occur due to the forces of gravity and muscle contraction. When load is applied to produce compression, the structure shortens and widens. Compression is always greatest on a plane perpendicular to the load. Usually, the greatest exposure to compression loads comes from muscles. Bone is often exposed to compression and is by far the best biological tissue at tolerating compression loads. Compression will occur on the concave side of a long bone during bending (Jette, 2006). Compressive loads applied to cartilage will result in deformation that gradually increases with constant loading over a period of time.
Tensile loads are common in the body and are most often seen at the musculotendinous units. In this area, the tissues react to strain elicited by the muscle contraction. Tension may also occur in ligaments and can be extremely high (Benjamin et al., 2006). Bone may be exposed to tensile loads, especially where tendons and ligaments attach, or in conjunction with bending loads with tension occurring on the convex side of the bending. When forces exceed the tensile limit of the bone, avulsion fractures can occur. These are more commonly seen in developing bony tissues where the attachment sites of tendons and ligaments may still be soft. Repetitive or high tensile forces from strong muscle contractions can result in tissue failure.
Torsional loads involve twisting. They occur as a result of a torque and can result in compression, tension, and shear stresses. Bone absorbs most of the torsional loads to which the body is exposed.
Shear loads occur at right angles to the long axis of a structure. Tissues are more vulnerable to a shear than any other type of load. Shear load exposure on the body is generally relatively low.
Bending loads are common and are most significant in bone. At least three forces are required to create a bending load, and one must oppose the other two.
Electrical, magnetic, and electromagnetic forces are nonmechanical forces that are relevant to physical therapy in the context of the electronically based physical agents that are used.
Reaction forces occur when a force is imposed on a system or body. Newton’s third law states: For every force there is an equal and opposite force (Wikimedia Foundation, Inc., 2012b). Reaction forces are the resistance of the body to the deformation or acceleration caused by the applied force. Two types of reaction forces are discussed in physical therapy ground reaction forces and joint reaction forces.
Application of Forces to the Body.
The behavior of biological tissue responding to loads can be defined by the amount of deformation that occurs. Biological tissues are pliable and have elastic properties. Elasticity can be described as the ability of a tissue to return to its original state following deformation caused by load (Lipowitz, 2010). Stiffness is the resistance to deformation caused by external loads. The degree of stiffness and amount of elasticity can be illustrated in a stress–strain curve of biological tissues (see Chapter 3). Loads applied in the elastic region will allow the tissue to return to its original state. Loads that carry into the plastic region will cause permanent deformation. In the plastic region, strain will continue to progress without the addition of further stress. The point at which this begins is called the yield point. If stress continues to be applied, failure will eventually occur. If the strain is held constant, then the stress decreases with time. This is relaxation.
Biological tissues are subject to the process of hysteresis, which is energy loss that occurs when a tissue is repetitively loaded and unloaded. This energy loss is expressed as heat. This concept may be of value when applying a mobilization force to stiff joint tissues. Repetitively loading and unloading the stiff joint tissues in the elastic range during a mobilization technique will cause energy loss to occur. Forces are going into the biological tissue, no deformation occurs, and energy is lost in the form of heat. Heating the joint tissues in this way lowers the stress–strain curve of the joint capsule, enhancing the stretch by allowing for higher strain under less stress and an easier reach into the plastic zone where changes occur, improving joint mobility.
Dynamics and Kinematics
Osteokinematics is the study of joint motion in relation to the osseous structures involved in movement (Lipowitz, 2009–2010). For example, shoulder osteokinematics involves the study of humeral motion relative to the glenoid, and stifle osteokinematics refers to the relationship between the femur and the tibia. Osteokinematic motion is measured to evaluate quantitative information of joint mobility or ROM.
The following terms refer to movement of limbs rather than joints:
Flexion and extension take place in the sagittal plane around a mediolateral axis (Tortora & Grabowski, 1993; Muscolino, 2011).
Abduction and adduction take place in the frontal/coronal plane around a sagittal axis (Tortora & Grabowski, 1993; Muscolino, 2011; Wikimedia Foundation, Inc., 2012a).
Rotation in limbs occurs in a transverse plane around a frontal axis, and in the spine occurs in a frontal plane about a transverse axis. In the canine spine, side bending occurs in the transverse plane (Tortora & Grabowski, 1993; Muscolino, 2011; Wikimedia Foundation, Inc., 2012a).
Diagonal Movements
The body does not always move in orthogonal planes about fixed axes; rather, it often moves on diagonal planes about moving axes. Even small amplitude movements tend to be more diagonal than orthogonal (Tortora & Grabowski, 1993; Muscolino, 2011; Wikimedia Foundation, Inc., 2012a).
Arthrokinematics is the study of motion that takes place between articular surfaces and related joint structures during osteokinematic motion (Mosby’s Inc, 2009). As a joint moves, causing opposition or separation of the long bones comprising the joint, specific translatory and/or angular movements occur between the joint surfaces. Osteokinematics is concerned primarily with limb motion whereas arthrokinematics is concerned with movements that take place within joints.
Arthrokinematic movements occur as roll, glide, or spin, and there are two types of arthrokinematic motions—joint play and component motions.
Joint play motions are not under voluntary control and occur only in response to an outside force. Examples are the additional passive range that exists at the end of all active ranges or when the clinician performs a cranial glide of the tibia. Component motions take place in a joint to facilitate a particular active movement. For example, with stifle extension, there is an associated cranial glide of the tibia. Osteokinematic motions do not occur normally without their corresponding component movements.
Manual interventions designed to improve joint mobility are selected based upon the assessment of these component motions. Theoretical constructs of normal component motions of peripheral joints are based upon the convex-concave rules originally developed by MacConail and later popularized clinically by Kaltenbourn (Jonas, 2005; Mosby’s Inc, 2009). Component motions in the spine are based upon studies of coupled motion that occurs with normal movement of the spine. Coupled motion refers to obligate motions that occur together in the spine due to normal forces and the anatomical features of the facet joints. For example, rotation in the cervical spine is coupled with side bending to the same side. Understanding how component motions influence normal joint movement allows the clinician to choose manual techniques to improve joint mobility.
To obtain clinically relevant information regarding component motions, these motions must be tested. This is accomplished by examination procedures designed to evaluate the availability of translatory motion in a joint. The amount of motion is tested by gliding one joint surface using a translatory or rotary force and critically evaluating how the joint responds to those forces. One of three findings can be expected: normal, hypomobility, or hypermobility. If a joint moves less than expected, a restriction or hypomobility may be present, and stretching or mobilization is indicated. If a joint moves more than expected, a hypermobility or instability may be present, indicating the need for internal stability via exercise or surgery, or external stability via bracing.
The quality of resistance a joint tissue provides at the extreme of each passive movement, both osteokinematically and arthrokinematically, has been termed an end feel by Cyriax (MacConaill, 1951). End feels transmit specific sensations to the examiner’s hands depending on the source of a joint’s stiffness at the end ROM.
End Feels
Assessing end feels properly can give information as to the type of pathology present which is important in determining prognosis and treatment (MacConaill, 1951). The following are the three normal end feels.
Bone-to-Bone
A hard, unyielding sensation that is painless. An example of normal bone-to-bone end feel is elbow extension.
Soft-Tissue Approximation
A soft, yielding compression sensation that stops further motion. An example is stifle flexion limited by the soft tissues of the gastrocnemius contacting the hamstring muscles.
Tissue Stretch
A hard or firm, springy feeling with an elastic resistance, or give, toward the end of the available range. This elastic sensation depends on the thickness of the tissue and can vary from highly to slightly elastic. An example is the end feel with normal carpal flexion. Injury to ligaments often causes a softer end feel until tension is taken up by other structures (Kaltenborn, 1989). This is the most common type of end feel.
There are five abnormal end feels (Kaltenborn, 1989).
Muscle Spasm
This is caused by movement, with a sudden arrest of the movement, often accompanied by pain. It is dramatic and hard. It is usually seen with inflammation or instability and the resulting irritability created by the movement.
Capsular
This is similar to tissue stretch but does not occur where one would expect it. It is a soft and boggy sensation. The ROM is reduced, and it is hypothesized that a tight capsule is at fault.
Bone-to-Bone
This is similar to the normal bone-to-bone sensation, but the restriction occurs before normal joint end range should occur. An example may be osteoarthritic changes in a joint such as the hip causing decreased ROM.
Empty
Considerable pain ceases the movement with no true mechanical restriction being detected. Examples include pain associated with joint movement with acute bursitis or neoplasm. No muscle spasm is involved.
Springy Block
This is similar to a tissue stretch but occurs where not expected. There is a rebound effect before the normal end of range, usually indicating an internal derangement within the joint, such as a torn meniscus.
Range of Motion
Assessment of active, passive, and resisted motions provides valuable information by isolating the source of the patient’s symptoms and evaluating the functional status of the tissues and structures.
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