"We all have something of magnetic and electric forces in ourselves, and in the same way as the magnet itself, we exercise an attracting and a repelling force, depending upon whether we are in contact with something similar or dissimilar."
Johann Wolfang vonGoethe Johann Wolfang vonGoethe came to this conclusion a long time ago, and there is no doubt that when we say people and events "affect us negatively or positively" we are talking about magnetism and magnetic qualities. There are many types of magnetic therapy devices on the market today for humans and for animals, with a vast array of prices and features. And there are virtually no side effects.
Sometimes we can use fewer medications for chronic problems by using magnetics for maintenance therapy. Magnetic therapies are flexible enough to be used for a wide array of injury and disease states. If you understand the differences between the major classifications of static, bi-polar and electro-magnetic field magnetic therapy systems, chances are better that you will choose the type that will significantly benefit the problem you are treating, and that you won't expect a magnet to do something it just can't do.
All types of magnets begin their work "magnetically," but once these fields enter an organism, their mode of interaction becomes electrical. Most magnetic therapies in wide use today fall into three categories: static, bi-polar and pulsing electromagnetic. They have different characteristics, different prices, and different applications.
Bar magnets, with an N pole and an S pole, are the most common form of magnet, although they come in many different shapes today. Bi-polar or multi-polar magnets have strips of N and S material fused into some sort of medium. They are usually sewn into wraps. And finally, pulsing magnetic field systems (PMF systems) contain coils of wire, a pulse generator and a power source.
There are a few basic concepts that form a baseline for a discussion about magnetic therapy. Magnetic strength is measured in gauss, and up to a point, more is better, since too little gauss can be ineffective for a large animal.
Certain materials like iron, cobalt and nickel make strong magnets, and "rare earth magnets" made of boron, cobalt and neodymium are the strongest, and most expensive magnets. Rare earth magnets are usually 2,000-3,000 gauss, up to 10,000 gauss, and they are typically found in bar magnets, also called "static" magnets. Most magnets are commercially manufactured from ferromagnetic alloys that measure between 400 and 1500 gauss at the surface of the magnet. The composition and method of manufacture determine the magnetic strength of the magnet. Larger magnets have more strength than smaller magnets, so both size and composition affect penetration. In any magnet, the magnetic field flows in lines of "flux" around the magnet, from N to S (Figure 1). The strongest lines of flux are those closest to the magnet, and they decrease in strength as you move away from the magnet. The flux field from a large bar magnet extends a good distance, and if the composition of the magnet is very good, it would extend even further.
Figure 1: Bar or Static Magnet.
As you might expect, larger magnets have more strength, as do rare earth magnets. Bi-polar magnets have the N and S poles very close together in some type of pattern, usually parallel strips, or checkerboard, or concentric circles (Figure 2). The placement of the poles close together means the lines of flux don't have to travel very far to reach the opposite pole, which limits the field. Most bi-polar magnetic strips are only about 1/16 of an inch thick, which limits their field.
Bi-polar strips place the North and South magnetic material very close together, to enhance the motion of ions in the blood. Ions are positively or negatively charged particles in the cells. Figure 3 shows the blood vessel with Na+Cl- (sodium chloride), which normally circulates with a net electrical charge of 0. The magnetic material, in this case a bi-polar strip of alternating N and S material, is placed perpendicular to the capillary. According to Faraday's law and the Hall effect, the resulting electromotive force (EMF), is greater when the angle at which the conductor cuts the magnetic field is greater. This holds true since, when the conductor is at right angles to the magnetic lines of force, it cuts the maximum number of lines of force per second, producing a maximum EMF.
Figure2: Different types of bi-polar strips, commonly found in magnetic wraps.
The separation of the ions results in the EMF, which liberates heat. The back and forth motion of the ions works to dilate blood vessels. The magnetically charged molecules move more efficiently through the body, increasing blood flow rate, and taking nutrients and oxygen to the injured areas.
Checkerboard and concentric circle patterns maximize this effect, because the design places a maximum number of alternating N and S fields, regardless of where the capillary lies. When using parallel bi-polar wraps, it should be placed at a 90-degree angle from the capillary for maximum effect. The Kobluk study -- published and well known among equine owners and trainers --showed increased activity of soft tissue and bone in 15 of 16 limbs after treatment with magnetic wraps (1). Although this study has been criticized since the patients were well and not injured, it is hard to argue with the conclusion, that it "could" be useful in injured limbs.
Pulsing Magnetic Field Therapy systems, or PMF, rely on basic principles of physics that utilize coils of wire and small electrical voltages to generate a pulsing magnetic field. Pulsing current flows through the coil, generating a magnetic field that alternately expands and then collapses. As the current flows through the wire, which is wound into a coil, it creates lines of flux.
The gauss of the field that develops depends upon two variables: the voltage, and the number of turns of wire. With more turns of wire, or more voltage, gauss increases (Figure 4). The gauss fields of 90 to 100 are measured as an average of the field, which is off, then turns on and peaks, and turns off again. A computer initiates the on/off characteristic of current through the coils, generating the pulsing magnetic field. Most therapeutic frequencies are found in the 5-20 pulses per second (PPS) range. The coils and the control unit are placed in pockets in a sheet or jacket. Since PMF completely permeates a living body, treatment times are typically from 30 minutes for muscle therapies to 5-6 hours daily for non-union fracture therapies. Pulsing from the coils can be felt by holding a strong magnet up to 18" away from the coil; even though a coil is not placed directly on an area, it receives the benefit of the magnetic field from the coils nearby.
A typical equine system contains ten to fourteen coils placed in a sheet. Dressage, show jumping and 3 day event competitors use them on a daily basis to treat stiffness and soreness. Leg boots, hock boots and neck wraps can be used at the same time to take care of all major muscles and joints. In case of leg or hock injury, there are stand-alone boots with a pulse generator and battery source, permitting use without a full body system.
CASE STUDIES
Figure 3:Blood vessel with sodium chloride (Illustration courtesy of Norfields.
- A large clinical study by Hermann Focke, was published in Der Prakische Tierart in 1982 (2). Focke studied 250 horses with a number of injuries, both acute and chronic, in ligaments, sheaths, and joints. In general, he treated acute injuries at 5 PPS with 20 to 30 gauss. For chronic injuries he used 10 PPS and 50 gauss. This study showed that younger horses reacted particularly well to PMF therapy, with problems resolving and not recurring at the 2-year point. Older horses with serious joint and tendon disease needed extended treatment. Many jumping horses who had been kept free from lameness with bute were free of the analgesics for 6 months. Patients with moderate or little lameness were exercised from the first day of treatment.
Figure 4:
Schematic of pulsing magnetic field.
- A more recent clinical study was presented in September 2002 at the American Equine Sports Medicine Conference in California by Dr. Kayla Shaw, regarding her use of PMF on osteolytic degeneration and bone healing. Horse Journal reported in September 1998 that PMF provides good (usually reliable) to very good (a reliable and predictable effect) for pain relief, reduction of swelling, control of inflammation and speeding healing. A variety of cellular effects are responsible for the improvements noted in Focke's study. Studies looking at the effect of PMF found that it activates cellular processes by means of induced electrical potentials.
Cadossi and others in 1988 summarized much of the work done earlier, pointing to the cell membrane as the target for activity (3). A healthy cell membrane has a voltage potential of 70-90mV, which is responsible for the movement of electrochemical ions through the membrane. Channels that normally move sodium and potassium into and out of the cell are affected by the pulsing currents, moving the ions across the channels in a way that is opposite that which would be expected according to their electrochemical potentials. When cells are injured or diseased, normal cellular responses are inhibited. Ion exchange and membrane potentials are abnormal, resulting in accumulated waste products. PMF restores a more normal ion exchange, improving cell metabolism and reducing waste products.
CONTRAINDICATIONS
If you have a fresh fracture, you need to wait until the injury is fourteen days old or magnetic therapy can actually impede healing. In case of an injury with bleeding, it must be stabilized before using PMF. When using static and bi-polar magnets, cautions are straightforward. Very ill patients should be treated for short periods of time when first beginning therapy. Wait before using magnetic therapy on a fresh injury or open wound. If there is a negative reaction to the therapy, you can either cut back on the treatment time, or discontinue treatment altogether.
Now that you know something about magnetic therapies, you can let your budget be your guide. Start out simple. Bi-polar magnetic materials can be purchased for as little as $15. Wrap the material in a polo wrap and place on the area. Or, if you don't want to make your own, for a bit more money, you can buy specially made wraps for tendons, hocks and feet. If these methods don't work, you may have a more deep-seated problem requiring a more expensive, deeper penetrating PMF system.
REFERENCES
1. Kobluk C. 1994. A Scintigraphic investigation of magnetic field therapy in the equine third metacarpus. Veterinary and Comparative Orthopaedics and Traumatology 7:9-13.
2. Focke H. 1982. Experiences with the use of magnetic field therapy in equine medicine (original article in German). Der Praktische, Tierarzi, 7.
3. Cadossi R, Emilia G, Ceccherelli G, Torelli G. 1988. Lymphocytes and pulsing magnetic fields. In: Modern Bioelectricity, Marino AA, ed. Marcel Dekker, Inc., New York.
Doreen Hudson is Vice President of Respond Systems, Inc., manufacturer of Bio-Pulse PMF and Respond Laser Systems. Located in Branford, Connecticut, they have designed, manu- factured and serviced the popular Respond Laser 2400 and Bio-Pulse magnetic field therapy systems since 1986. They were named official supplier to the United States Equestrian Team in 1995. Contact Doreen Hudson at Respond Systems, Inc., 20 Baldwin Drive, Branford, CT 06405, 1-800-722- 1228.