Veterinary rehabilitation and its application in pain management (Proceedings)

What is veterinary rehabilitation?

In order to discuss the application of veterinary rehabilitation in pain management, it is important to understand what veterinary rehabilitation is. Many people believe that veterinary rehabilitation consists of a series of therapeutic exercises, especially involving the Under Water Treadmill, which can be applied to our animal patients. The notion that this field would be easy to grasp, with intuitive reasoning, and little training, has lead many to attempt to add rehabilitation to their veterinary practices. In reality, veterinary rehabilitation is the application of an all-new diagnostic algorithm to our patients. The physical therapy evaluation focuses upon soft tissues rather than bone and joint. It involves special tests that allow for determination of specific tendinopathies and soft tissue abnormalities. The use of Objective Outcome Measures, evaluated with Goniometers and Gulick Girthometers provides clear evidence of the progress of the patient during and after rehabilitation therapies have been applied. The emphasis in rehabilitation therapy is on meeting goals that are functional for the patient.

The goals of rehabilitation include the restoration, maintenance and promotion of optimal function and quality of life as they relate to movement disorders. The majority of rehabilitation therapeutics involves manual therapies and problem solving rather than the use of 'toys'. Examples of manual therapies include joint mobilizations, focusing on arthrokinematics rather than osteokinematics, stretches, focusing upon flexibility and hypo mobility, and therapeutic exercises, progressing from concentric to eccentric contractions. Equipment utilized on a regular basis in veterinary rehabilitation includes LASER, ultrasound, electrical stimulation, physioballs, therapy bands, rocker/wobble boards, Cavaletti poles and land treadmills. Hydrotherapy equipment can include pools, resistance pools and underwater treadmills.

Future trends in the industry

What is driving this new field? Public awareness is bringing dog owners to veterinary hospitals, expecting state-of-the-art care for their pets. This is not unlike Acupuncture's rise in the 1980's...client-driven demand for new veterinary services. The current drivers include the huge interest in Agility and Flyball in the US. In addition, the government is now seeking rehabilitation care for service dogs injured in the line of duty.

The 6th International Symposium on Veterinary Rehabilitation will take place in August of 2010 at Auburn University's College of Veterinary Medicine. This biannual symposium alternates between the US and Europe. The 2010 meeting expects to draw nearly 500 people from over 20 countries for 4 days of lectures and laboratories. National veterinary meetings in the US have also seen growing interest in rehabilitation medicine. The ACVS, NAVC and of course CVS have all progressed from brief mentions of rehabilitation to hosting full day lecture-lab sessions on rehabilitation.

Pain management in rehabilitation medicine: diagnostic techniques

The aforementioned diagnostic techniques that physical therapists bring to veterinary rehabilitation allow for improved care for patients who were previously lumped into the 'soft tissue injury' category. By determining specific soft tissue pathologies, we are able to apply focused therapeutics, providing considerably better outcomes than our former "Rest and NSAID's" approach. The soft tissue injuries that are now commonly diagnosed include Supraspinatus Tendinopathy, Medial Shoulder Instability, and Iliopsoas Muscle Strain. In order to diagnose a problem, we must be very familiar with what is normal in joint, ligament, muscle and tendon behavior. A physical therapist approaches a patient in a way that focuses upon the soft tissues surrounding the bones and joints and upon the interaction of joint surfaces during movement.

A common finding with soft tissue injuries is abnormal joint range of motion. Causes of abnormal range of motion include, but are not limited to intra-articular lesions, joint capsule pathology, ligament shortening, pain, and swelling in or near the joint. How can we tell these apart? Physical therapists use End Feels here. An End Feel is defined as the sensation or feeling which the therapist detects when the joint is at the end of its available PROM. There are several End Feels that are commonly used.

Joint mobilizations

A joint mobilization is a manual technique used to assess a joint and to improve joint arthrokinematics by stretching the joint capsule, ligaments, or adjacent fibrosis. Joint mobilization is accomplished through glides, oscillations, distractive forces and or compressive forces on the joint surfaces. There are several grading systems to rate the joint mobilizations. The Kaltenborn Grading System is commonly used in the US. When assessing a patient's joint, the scores can read 0 to 6, with 0 being a fused joint, 6 being a luxated joint and 3 being normal. The combination of End Feel and Joint Mobilization assessment helps the physical therapist to differentiate the tissue(s) which are injured, causing pain, or dysfunctional.

When treating a patient, joint mobilization affects the joint arthrokinematics by improving joint lubrication, modulating mechanoreceptors, and decreasing sensory input. Therapeutic glides are ranked Grade I to V. A Grade 1 glide is a fast, small- amplitude glide at the beginning of available range. This is the grade used for pain management in the immediate post injury or postoperative period. Grade II glides are slow, large-amplitude glides through the first half of range of motion. These mobilizations improve arthrokinematics, providing early range of motion and preventing painful dysfunction. Grade III glides are slow, large- amplitude glides in the mid to end range of motion that create joint capsule and ligament stretching. Grade IV glides are fast, small- amplitude glides at end range of motion, and are designed to resolve inappropriate fibrous tissue adjacent to the joint. A Grade V mobilization is called a Manipulation and is a small-amplitude quick thrust performed at the end of the arthrokinematic range. To perform a manipulation, one must be trained in veterinary chiropractic.

Pain management in rehabilitation medicine: Physical modalities

Traditionally in veterinary medicine, ice therapy has been the principal non-medical method of addressing immediate post-operative or post-injury pain. Physical therapy brings a new set of modalities for addressing pain during this period.

Most of us are familiar with diagnostic ultrasound and surgical Lasers. When we hear physical therapists discuss the use of ultrasound and LASER, the temptation is to believe that we already have these tools at our disposal. In reality, the ultrasound used by PT's is quite different from the diagnostic ultrasound with which we have experience, and the low level LASER (LLL) cannot be interchanged with the higher powered surgical LASER.

Physical modalities commonly used in human physical therapy, and now in veterinary rehabilitation include electrotherapy, electromagnetic fields, light, heat, sound, and water.

Electrotherapy

Electrotherapy can affect the sensory and the motor nerves. Indications for electrotherapy include wound healing, pain control/relief, reduction of inflammation, muscle re-education, reversal of atrophy, and strengthening. Electrotherapy works at many levels. At the cellular level, it causes excitation of nerve cells and changes in cell membrane permeability, and stimulates protein synthesis, osteosynthesis and fibroblast formation. On the tissue level, electrotherapy causes skeletal muscle and smooth muscle contraction. On the segmental level, electrotherapy facilitates muscle-pumping action, which improves joint mobility and circulatory and lymphatic drainage.

Generally, we think of transcutaneous electrical nerve stimulation (TENS) as a purely sensory therapy. TENS works by stimulating faster sensory nerves with an electrical impulse that causes overloading of interneurons. This limits the ability of sensory nerves to transmit their pain signals to the brain, creating analgesia for the patient. This effect is short lived, generally not lasting more than 1 hour past the treatment period. In veterinary rehabilitation, this modality is used immediately post operatively, and during therapy, allowing the patient to work through a painful treatment.

Motor nerve stimulation is called Neuromuscular Electrical Stimulation (NMES), and is achieved with a different piece of equipment from the TENS. NMES works on motor nerves and impacts muscle fibers. It is particularly useful in patients who cannot perform voluntary movement, who have edema, or delayed wound healing. In the patient who is able to stand, NMES can cause increased muscle contraction during weight bearing, and in the ambulatory patient, timed NMES can assist in muscle re-education during gaiting.

NMES is delivered to the patient via leads and electrodes. The electrodes must by flexible to conform to the skin. They must also have low resistance (less than 100 ohms), be highly conductive, reusable, inexpensive, and an appropriate size for the patient. Most NMES machines come with disposable electrodes which have a sticky side, designed for multiple uses on human patients. These electrodes can be used on our veterinary patients, but quickly lose their adhesive due to hair and dander accumulation. We recommend the use of non-sticky carbon electrodes, which use gel as a medium to transmit current. These electrodes can be taped on for the 15 to 20 minutes of treatment time. There is no need to clip the patient, as long as sufficient gel is used.

Contraindications for electrotherapy include treatment over areas of electrical current, such as pacemakers, the carotid sinus, the cervical ganglia, and heart. Any modality should be avoided (or at least used with precaution) in pregnant patients or over malignancy.

Light therapy

"LASER" is Light Amplification by Stimulated Emission of Radiation. By definition, a LASER must be collimated and monochromatic. Penetration of LASER energy is determined by the wavelength, and many wavelengths are patented. The physiological effects of LASER stimulation include accelerated cell division via mitochondrial stimulation, increased leukocyte phagocytosis, stimulation of fibroblast production, enhanced synthesis of ATP, and angiogenesis. Treatment with LASER is indicated for pain management, control of inflammation, and tissue healing.

The power of a LASER is measured in milliwatts to watts. There are four classes of LASER: Class I has less than 0.5mW of power. A common Class I LASER is a garage door opener. Class II Lasers have up to 1.0mW of power. Most LASER pointers are in this class. Class III is divided into IIIa and IIIb, with Class IIIa having 1.0 to 100mW, and IIIb's having up to 500mW of power. These represent the majority of therapeutic or 'cold' lasers available today. Class IV Lasers have over 500mW of power. These are 'hot' Lasers commonly used in surgery.

LASER therapy is measured in Joules of energy. A Joule is the energy delivered by one watt of LASER energy in one second. To get 1 Joule of energy delivered from a 500mW LASER, we would need to treat for 2 seconds. (500mW X 2 sec=1Watt Second). Most therapeutic regimens from current research call for one to eight Joules of energy. As the common cold LASER delivers 500mW of power, treatment times are 2 to 16 seconds per site. As stated above, the depth of penetration is determined by the wavelength of the LASER. Higher power simply delivers this energy to the same depth at a faster rate.

Sound therapy

Two forms of sound therapy are commonly used in veterinary rehabilitation. Both can be applied to the pain management protocol for our patients. Therapeutic ultrasound converts electricity to sound waves by means of a piezoelectric effect upon the crystal housed in the transducer head. Unlike the diagnostic equipment, therapeutic ultrasound works at 1MHz to 3MHz, with the desired results being thermal effects and tissue modulation. Common uses for therapeutic ultrasound in veterinary rehabilitation include heating areas of muscle spasm to create relaxation, treating bicipital tenosynovitis to break up the debris within the tendon sheath, and stimulating the insertion of the iliopsoas muscle to encourage healing of a strain lesion. The tissues through which they pass will attenuate ultrasound waves. Bone will attenuate the waves the most, followed by cartilage, tendon, skin, blood vessel, muscle, fat, and finally blood. This must be taken into account when determining the treatment intensity for a tissue or lesion that sits deep to any of these tissues. Hair is another possible attenuator of sound waves. Some therapists advise shaving the fur over the area to be treated. Others say that this is not necessary if the fur is wet, and sufficient gel is applied to the area.

Extracorporeal Shock Wave Therapy is a newer modality in veterinary medicine. FDA approved for treatment of several painful lesions in human medicine, including plantar fasciitis, ESWT has been applied to painful OA lesions in veterinary practice, including hip and elbow dysplasia and Supraspinatus Tendinopathy with excellent pain relief results being reported. ESWT works by releasing a sudden high-powered shock wave resulting in tissue modulation in a very focused depth of tissue. This modality does require deep sedation or anesthesia as the treatment is uncomfortable for the patient, however the patient experiences pain relief immediately post treatment, which can last for days to weeks.

Thermotherapy

Heat can be applied by hot packs, infrared light, hydrotherapy, and by therapeutic ultrasound. The effects of thermotherapy are vasodilation with secondary increased local circulation, decreased pain, relaxed muscle tone, reduced muscle spasm, increased tissue extensibility, increased cellular metabolism, and increased local tissue oxygenation. Heat is generally used to reduce pain from arthritis, trigger points and muscle spasms, and to prepare tissues for exercise or stretching. Precautions of using heat therapy include impaired thermal sensation, recent hemorrhage, malignancy, and acute inflammation. Cryotherapy can be applied via ice bath, ice massage, ice pack, vapocoolant gel, or circulating ice compression units. The beneficial effects of cryotherapy include vasoconstriction; reduced cellular metabolism; decreased nerve conduction velocity, and decreased production of pain mediators, leading to analgesia; reduction of edema and decreased muscle spasm. Metabolism may be decreased by more than 50%, which facilitates oxygen diffusion into the injured tissues. Joint range of motion is improved through suppression of excitatory muscle spindle afference. Intermittent pneumatic compression, when combined with cryotherapy has been shown to prevent edema formation, increasing blood flow, and stimulation of tissue healing. Although static compression is effective in edema reduction, intermittent compression optimizes lymphatic drainage.

Conclusion

There are many physical modalities available to the veterinary rehabilitation therapist, each of which can add tremendous benefit to the patient. This is not to say that by simply purchasing these modalities and applying them to your patients you can expect great results. Excellent manual skills, meticulous diagnostic techniques, and creative problem solving are all essential before adding a modality. The benefits of this combination approach, applied with the correct medical pain management and weight management can bring great results to your post-operative patients, geriatric osteoarthritis patients, and elite athletes. The application of pain management techniques in human physical therapy has progressed well beyond the joint mobilizations and physical modalities described here. PT's address neural tension, neural irritation, and neural hypersensitivity. There are many physiotherapy continuing education courses that address these topics, including, for example, "Nervous System Mobilization" (www.noigroup.com, www.neurodynamicsolutions.com). To offer our veterinary patients the optimal care, we should work together with pain management practitioners and physical therapists to develop a truly balanced pain management plan for each patient.

References

1. Slauson, DO, Cooper DJ, Mechanisms of Disease. 3rd ed. St. Louis:Mosby:2002

2. McGeown JG, McHale NG, Thornbury KD, Effects of varying patterns of external compression on lymph flow in the hind limb of the anaesthetized sheep. J Physio, 1988;397:449-457.