Using sound is nothing new to medicine. Diagnostic ultrasound machines generate pictures of injured tendons and ligaments by using sound waves that bounce back off objects and appear on the screen. Ultrasonic scalers annihilate plaque on dogs’ teeth.
Powerful, well-focused sound-wave generators disintegrate kidney stones in people. Doctors even use ultrasonic scalpels and machines that can destroy tiny masses of tumor cells, while leaving the surrounding tissues intact.
This sound technology is catching the attention of more equine veterinarians as therapy, beyond its diagnostic and surgical use. But, like most high-tech therapies, it’s expensive, requiring a cost-versus-benefits decision. To find the answer, we used both ultrasound and infrasound on horses with chronic and acute pain.
We looked at safety, time involved and ease of treatment. We studied any available scientific studies we found about these therapies. Then, we noted changes in the test horses, who had a variety of problems involving muscles, stifles, tendons/ligaments, curbs and painful joints. Some results were more dramatic than others, but all displayed a lesser degree of pain and inflammation.
Ultrasound
The difference between the terms “ultrasound” and “infrasound” is not that difficult to understand, if you relate it to sound. Ultrasound is composed of waves with a frequency too high to be audible (above 20,000 Hz or cycles per second). Infrasound has a frequency too low to be audible (below 20 Hz).
One of the first things you’ll notice about therapeutic ultrasound is that it generates heat in the treated area. Indeed, many of the noted benefits of ultrasound center on heat-related effects, including increased blood flow, relaxation of tensed muscles/ligaments, and soothing warmth. But, the physical reactions actually go far beyond this.
Therapeutic ultrasound applied to tissues results in increased levels of a cell’s stress proteins (also called heat shock proteins or HSPs). The HSPs protect intracellular structures from oxidative damage, encourage synthesis of cell proteins and accelerate healing.
HSPs also stimulate an increase in antioxidant defense mechanisms inside cells, an effect that can last for several days. In arthritic joints, increases in HSP levels triggered by ultrasound correlate with increased levels of GAGs (glycosaminoglycans) in joint fluid and the healing of cartilage lesions. Once healing occurs, HSP levels drop back to normal.
Ultrasound can also increase the production of specific types of intracellular chemicals called cytokines, which are responsible for encouraging the growth of new blood vessels. While there is much yet to be learned about biochemical responses to ultrasound, the glimpses we have show more involved than just a mechanical pushing, shoving and heating of the tissues.
Most equine practitioners limit therapeutic ultrasound use to muscular and tendon/ligament injuries (sprains, strains, chronic stiffness). Because of the research regarding the effects of ultrasound on healing cartilage lesions and the production of joint GAGs, we included a variety of joint problems in our trials. Our chart on page 13 shows the types of problems we treated in our field trial and the outcomes.
Mettler Sonicator 730 Ultrasound
As with many therapy devices, mastering the operation of the machine is the biggest battle. Delivering the treatment is a snap.
The Mettler Sonicator 730 we used actually made the selection of settings relatively easy, and the automatic timer eliminated any risk of overtreatment from not paying attention. Frequency of the waves is determined by the head you use and is clearly marked on its handle. Lower frequency (1.0 MHz) penetrates deeper and heats more slowly. We used this for all problems except curbs (see chart at end of story).
Dosage is a function of time and intensity. The amounts are set via buttons and digital displays on the machine, as is the choice between pulsed and continuous emission of ultrasound. Details of settings we found most effective are listed in the chart. Always use pulsed instead of continuous emission to minimize tissue heating. Note: Anyone considering the use of ultrasound at home should have a thorough education in the operation of the equipment, safety factors and selection of treatment parameters by a professional.
Ultrasound waves are not well conducted by air and require the use of gel as a coupling medium between the skin surface and the treatment head. However, since treatment times were relatively short, we didn’t mind the extra effort needed to wipe and wash the gelled areas. Leaving gels on won’t hurt or irritate the skin but does result in a flaking residue when it dries. Gels are best removed by wiping off the excess and cleansing the area with a mild soap.
Infrasound
Unlike ultrasound, infrasound does not heat the tissues. Because it has a low frequency, wavelengths are long and penetrate better than other types of sound. It also doesn’t require the use of a coupling gel. Although traditional medicine considers infrasound basically a deep-tissue massage, the idea behind using it is different.
Qigong is an ancient Chinese discipline of mental and physical exercises designed to strengthen the body’s Qi (“chi”) or its life force. There are several hundred versions of Qigong — some of which are medical — focusing on either self-healing or a master’s ability to heal by touch.
Questions of individual healing powers aside, researchers found that there is an energy field containing infrasonic waves around the human body. The researchers also found Qigong masters could emit infrasonic waves over 100 times stronger than those of ordinary people and could indeed enhance or weaken energy fields of other people. This finding is what led to the Equisonic QGM.
Researchers in Eastern Bloc countries have also been using infrasound waves to treat musculoskeletal injuries for years, noting it has obvious analgesic effects. These early applications of sound therapy are what eventually led to the development of more focused, powerful sound/pressure waves, now being used to actually treat many equine lamenesses (see sidebar at end of story).
Equisonic QGM Infrasound
Infrasound as a treatment modality is in its infancy. The China Healthways Equisonic QGM unit we used has been available for about three years (its human counterpart is the Chi machine).
Information on what might be going on at the cellular/biochemical level is basically nonexistent. There are some reports on using infrasound for musculoskeletal disorders in Russian medical literature, but we could not find full articles and the abstracts we read don’t have much information in them.
However, a study by Dr. Ron Riegel in Ohio looked at the effects of the Equisonic QBM on hock inflammation in racing Standardbreds and showed there is more going on than just a pain-blocking effect. This machine emits infrasonic, low-frequency sound waves (7.53 to 13.85 Hz). Horses were matched by age and breeding and scanned using thermography for inflammation in the hocks. The degree of inflammation in the right and left hocks was similar to within 20%. The right hock was treated with the left hock left as a control.
A 10-minute treatment to the hock, including focusing on local acupuncture points, resulted in a 20 to 30% decrease in thermographic readings at 30 minutes, which returned to baseline by six hours. With a 20-minute treatment, 40 to 60% reductions were noted, which took 36 hours to return to normal levels.
When two 20-minute treatments were done, 12 hours apart, a major change was noted. The average 50% change jumped to almost 80% 24 hours after treatment and stayed at 50% or higher to the 120-hour mark, down to 32% at 144 hours and back to baseline at 156 hours.
Even though only the right hock was treated, drops in thermographic readings were also observed for the left hock with all but the initial 10-minute exposure test. This was presumed to be due to the animal not overstressing the left hock when making up for the right, but some sort of central effect can’t be ruled out.
In the final phase of the study, both sides were treated, concentrating on the 12 acupuncture points associated with hock dysfunction. Results were dramatic. A 100% reduction in thermographic readings was found beginning 30 minutes after treatment and persisting for 72 hours. At 96 hours, it was still 95%. At 120 hours, it was 79%. At the 7.5-day mark, there was still almost a 50% reduction in the thermographic readings.
All horses continued to train as usual during the treatment. Significant reductions in muscle enzymes in treated horses was also noted, compared to an untreated control group. Performance was also better.
Bottom Line
Supporting scientific studies are more readily available for ultrasound than infrasound therapy, but we saw benefits from both forms of therapy.
Although ultrasound requires a conductor gel, this inconvenience is balanced out by shorter treatment times. Still, we found infrasound was better tolerated and more effective with acute muscular problems.
Both helped with chronic tendon problems. Infrasound was better for those that involved a tendon/ligament and bone junction, but ultrasound with ice lead to more rapid control of acute low-grade tendon problems and also seemed better for treatment of curbs. This was in terms of time to actual resolution of the problem. The control of symptoms was good with both.
Which is better for joints is a tough call. Both gave excellent symptomatic control of joint problems, but it remains to be seen if infrasound can match the documented benefits in terms of actual healing and joint GAG/mucopolysaccharide levels that have been shown for ultrasound.
From a safety and overall ease-of-use perspective, we prefer the Equisonic QGM unit for owner/trainer use. It wins on price, too. However, if your vet suggests ultrasound, jump at the chance. It may save you down time or prevent the need for risky injections — and your vet may have a unit to rent.
Also With This Article
Click here to view ”Sound-Wave Therapy.”
Click here to view ”Field Trials With Ultrasound And Infrasound.”
Click here to view ”Infrasound Acupuncture.”
Click here to view ”Drive In The Medicine.”
