Modalities Used in Animal Physiotherapy
Modalities are the physical entities used a part of a treatment plan. Many of these modalities introduce an energy source to the body to stimulate or support the healing process. For instance, thermotherapy and cryotherapy, electoral muscle stimulation, laser therapy, ultrasound therapy, pulsed electromagnetic field therapy, extracorporeal shockwave therapy and hydrotherapy.
Crypotherapy (Superficial cold therapy)
Cryotherapy is most often used in the acute phase of an injury or immediately post operatively. It can also be used in exercise-related injury. Application of a cold pack to an area will reduce blood flow to that area. Cryotherapy has been shown to interfere with pain transmission. It also reduces oxygen demand from the surrounding tissues and will help reduce swelling. If cryotherapy is applied under pressure, this results in greater reduction in swelling and reduced pain scores.
Superficial Hot Therapy (Thermotherapy)
Superficial heat is often used in chronic conditions such as OA and can also be useful for reducing muscle spasm. It promotes blood flow to an area, reduces pain and increases joint and soft-tissue flexibility. Superficial heat will penetrate about 1-2 cm in depth. Sources of heat include a damp towel placed in the microwave, wheat bags, heat mats, gel packs heated in hot water and special hot packs that generate heat on the mixing of two chemicals. Again a towel or similar be placed between the hot pack and the animal's body.
Electrical Muscle Stimulation (EMS)
Electrical muscle stimulation is sometimes referred to as Estim or NMES (neuromuscular electrical stimulation). These are all the same thing. EMS is sometimes also referred to as TENS (transcutaneous nerve stimulation). Whilst both use the same machine, TENS uses completely different settings to achieve pain relief by stimulating the sensory fibres. EMS is used to reverse or reduce muscle atrophy by stimulating motor fibres.
Mobile units are most commonly used in veterinary physiotherapy. EMS machine consists of a small box with a battery and buttons for adjusting the settings and two sets of leads. Each set of leads has a pad at each end. The pads are placed at the top and bottom of the muscle and a current is passed. This causes the muscle to contract. Clipping of the furs and application of an aqueous gel are required to ensure a good contract. The kit comprises two set of leads, so that two muscle groups can be stimulated at the same time.
For instance, one pair of pads could be attached to the quadriceps muscle group and the other to the hamstring group of muscle. The muscle can be made to contract at the same time, in which case the joint will not move, or set contract alternately, in which case the stifle extends and flexes as each group contracts.
Lasers have been used or many years in human physiotherapy and are now beginning to make quite an impact in the veterinary market. Penetration is determined by wavelength. Wavelength is predetermined in each machine. Therapeutic wavelength range is 600-940nm. Lasers deliver engird (joules) that depends on the power (watts) of the laser and the time the laser is on. Class 3b lasers only have up to 500mW of power. The laser probe can be directed at the target joint or tissue and held in place while the dosage is delivered (normally measured in joules per centimetres squared). A Class 4 laser produces so much energy that the lead has to be held away from the patient and constantly moved in order to prevent burning. Health and safety for Class 4 lasers requires that all people in the room where lasers are used must wear protective goggles, the patient should be hooded, the doors to the room must be locked or a clear NO ENTRY LASER THERAPY IN PROGRESS sign must be displayed.
The effects of therapeutic lasers cause an increase in cell metabolic rate by affecting part of Kreb's Cycle in the mitochondria. The result is an increase in ATP production and cell metabolic rate. This increase in cell metabolic rate results in faster production of the material the cell manufactures. For example, fibroblast produce more collagen and chondrocytes produce more cartilage matrix.
Lasers also decrease the number of microorganisms, by increasing lymphocyte production, which can have a dramatic effect on granulating wounds and contaminated/infected areas.
Lasers also cause the local release of nitrous oxide, which causes vasodilation. Therefore, lasers increase the blood supply to an area. Lasers also reduce the production of prostaglandins and Cox-2 (cycle-oxygenase coenzyme-2) in the synovial membrane and synovial fluid and in so doing reduce joint pain. Lasers also reduce pain by reducing nerve firing at neuromuscular junctions. Lasers also cause the release of endorphins that enhance pain relief.
Pulsed electromagnetic field therapy (PEMET)
This is often referred to as short wave. At higher power level (over 5W), there can be some thermal effects. There is little or no scientific evidence to support the use of static magnets as therapeutic agents despite their popularity. The exact mechanism of action is not yet known. It has been suggested that PEMET interferes with nerve transmission in small unmyelinated nerve. For instance, C fibres (pain) by changing resting cell membrane potentials. Also in damaged tissue, there is a leakage of potassium from within cells into the interstitial tissue. This again alters the resting cell membrane potential. It is thought that PEMET can increase ion exchange in areas of damage. Ion exchange is responsible for oxygen utilisation within the cell.
The system consists of a mat that contains a wire coil and a control box. Electric current is passed through the wire coil which produces a three-dimensional magnetic field around the coil. The current is switched on and off (pulsed) very rapidly. This background pulse may then have an interference pulse applied. Settings vary from manufacturer and model. The action of PEMFT is aimed at blocking pain transmission or increasing oxygen utilisation in areas of damage.
The area to be treated is positioned so as to be in the magnetic field. This may just involve lying on the mat or wearing the coat. Treatment times are up to 20 minutes. The effects of PEMET will last for approximately 6 hours after treatment. Treatment can be repeated twice daily. PEMFT units are inexpensive and maybe considered for owners to buy for treating their animals at home.
Extracorporeal shockwave therapy (ESWT)
Extracorporeal shockwave therapy (ESWT) does not involve electrical shocks. It is sometimes referred to as high-energy pressure therapy. It uses a very short burst of very high-energy waves or pulses to create large sudden changes in pressure. ESWT penetrates deeper than any other modality. ESWT works in two ways. The first is by causing micro-fractures in the target tissue be it bone or soft tissue. These micro-fractures causes a new wave of inflammation. ESWT is particularly useful in treating tendons and ligaments where often the inflammatory process has stopped despite the healing process being incomplete. ESWT also stimulates the production of angiogenic growth factors that promote increased blood supply to the area.
The second way ESWT works is as the shockwave passes through the tissues, there is a void behind the wave. Cavitation bubbles form in this void. When the cavitation bubbles hit a hard surface, they collapse. As the bubbles collapse, they break down mineral deposits, such as calcified nodules in tendons.
A gel is applied to the dog's coat to ensure good contact with the head (trade). Different trade sizes are available for different target areas. Typical settings for shoulders tendinopathy in a Labrador would be 800-2000 shocks per treatment depending on type of ESWT machine. The treatment time is only a few minutes. Occasionally, dogs may feel a littler discomfort for 48 hours after treatment.
These are similar to a human treadmill, but have sides to prevent the dog from jumping off. Land treadmills are good for strengthening, endurance and cardiovascular fitness. Most are able to incline/decline that also allows increased weight distribution to back/front legs accordingly. Care must be taken hen using the incline/decline not to exacerbate or over load pathological conditions such as hip OA or carpal hyperextension.
Hydrotherapy has become well established as a treatment options for animals. Hydrotherapy works in several different ways to facilitates a return to normal function. In relation to water temperature for hypdrotherapy, be it a pool or underwater treadmill, is between 29 and 32 degrees C. This has the effect of warming and increasing blood supply to the submerged tissues as well as relaxing the patient. It provides an excellent environment for doing therapeutic exercises that maybe difficult on land. The warm water also produces sensory stimulation that is important in spinal cases.
For buoyancy, the more of the body that is submerged, the less weight will be taken through the joints. This allows painful joints to move more easily due to reduced loading. Hydrostatic effect is the pressure the water puts on th parts of the body that are submerged. The hydrostatic effect will help reduce swelling and venous congestion in the sub-chondral bone that has been cited as a major cause of pain in arthritic joints. Moreover, water viscosity provides resistance to movement. This is an extremely good way to help rebuild muscle. Resistance can be further increased by the use of water jets. The resistance can also be useful to correct gait abnormalities such as the swaggering gait with hip dysplasia.
The water offers support to the body that it would not experience on land. This is useful for the neurological patient who maybe uncoordinated and liable to falling. The water will support the body and slow down the fall. This allows the patient to take more time to correct the incoordination and avoid failing.
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