Veterinary LASER therapy: what, why, how?October 25, 2016 7:43 pm
So, LASER seems to be a bit of a fashionable thing to use at the moment in the veterinary sector. But, what does it do, is it any good or is it just a funky placebo effect for the owners? I have a Class 3b LASER and use it a lot; I think it’s a very useful adjunct to physiotherapy so I thought I would put some facts down here.
The first clip shows me performing LASER therapy for pain and inflammation using the cluster probe to cover larger areas of a chronic soft tissue injury. In the second clip I am treating a facial skin tag on a lovely elderly Labrador.
What is LASER?
LASER is an acronym for Light Amplification by Stimulated Emission of Radiation; therapeutic LASER as physiotherapists use it can also be called Low Level Laser Therapy (LLLT) or Low Intensity Laser Therapy (LILT). Lots of words, but what is it? Simply, it is light. It can be transmitted, reflected, refracted and absorbed just like all light waves and can be placed within the electromagnetic spectrum.
Where a LASER sits in the spectrum depends on the gain medium, this is the material being stimulated, usually electrically, which amplifies and produces the LASER beam. Different wavelengths (colours) are thought to affect different structures within the body. For example, red wavelengths are thought to be good for tissue healing whereas blue wavelengths are thought to have antibacterial effects.
There are a few properties of LASER that make it different from simply using a torch. The three main differences are:
- Monochromacity (only one wavelength/colour)
- Coherence (all waves are in phase with each other), and
- Polarisation (the vibration of the waves occur in the same plane)
Research has been done into all these aspects and the current belief is that monochromacity is probably most relevant in therapeutic terms. So, this means LED light that is also monochromatic but not coherent might be just as useful and indeed, there are devices available that use LEDs rather than LASER. The plus is these devices are generally cheaper but there is currently less research into LED light therapy, and the power output might have an influence on penetration depth within the tissues.
Types of veterinary LASER units
There is Class 3b vs Class 4. A lot of the veterinary LASER units are Class 4, the ones that Chartered Physiotherapists have been using on humans for decades are Class 3b. So, what does that mean?
Simply, the class of a LASER denotes how powerful it is. The higher the number, the greater the power. Surgical LASERs sit in Class 4. The benefit of more power in a therapeutic LASER can be put in simple terms; it takes less time to impart the same amount of energy to the tissues when compared to a Class 3b LASER. The possible negative effect of more power, however, is heating. The Class 3b LASERs have no distinguishable thermal effects on the tissue (heating is not desirable), while Class 4 might do. The manufacturers of the Class 4 LASERs all have research and/or have integrated technology to negate the thermal effects, so this may not be a problem.
Personally, and this is purely my own preference, I use a Class 3b LASER; The Ralph Mobile Physio & Rehab service uses the Chattanooga Intelect Laser. I haven’t found any animal (or human) so far that I couldn’t treat because it took a few seconds longer to deliver the dose. Having said that, I also know a lot of ACPAT physios who use Class 4 LASERs and would advocate them over Class 3b.
So, what does LASER do to the tissues? In the most basic terms, it is a way to deliver energy to the tissues. The most common term used in the literature is photobioactivation. Karu (1987) states that DNA & RNA both change their activity with irradiation with LLLT, but don’t absorb light themselves. This is done instead by the cell membrane and sets off a cascade response.
The working hypothesis is that a damaged cell, as would be present in a soft tissue injury for example, is more receptive to light energy than the surrounding, healthy cells. These cells use the light energy to attempt to heal themselves.
In vitro, this has been proven. There are many cellular and physiological effects that LASER has been shown to influence. The research in vivo however is not as robust. A list of potential effects that have in vitro evidence are listed below:
- Altered cell proliferation
- Altered cell motility
- Activation of phagocytes
- Stimulation of immune responses
- Increased cellular metabolism
- Stimulation of macrophages
- Stimulation of mast cell degranulation
- Activation & proliferation of fibroblasts
- Alteration of cell membrane potentials
- Stimulation of angiogenesis
- Alteration of action potentials
- Altered prostaglandin production
- Altered endogenous opioid production
I can’t tell you anymore about the efficacy of the research myself. I got the majority of these facts from Professor Tim Watson’s site electrotherapy.org; and would recommend you visit it yourself for much more in-depth information. What I can say is I’ve used LASER throughout the sixteen plus years I’ve been a Physio, both on human and non-human animals, and truly believe that it has benefited the majority of patients I have used it on, beyond a flashy “you must wear these sunglasses” placebo effect.
LASER therapy may be used for example in some patients with joint, muscle, ligament or tendon problems; it may also be applied in the treatment of wounds* and skin disorders.
(*You can read more about the use of LASER therapy for wound healing in dogs here.)
BUT, just like every other “tool” in my physiotherapy box, it is seldom used exclusively (wounds and dermatological conditions are an acknowledged exception here), and should be offered only after a thorough assessment and subsequent generation of a problem list and treatment plan.
Please comment with your preferences and thoughts about LASER, I’d love to hear your views.
Thanks for reading,