I love to watch TV reality shows about veterinarians. There are quite a few of them now. My favorite is “The Incredible Dr. Pol.” I learn a lot from them, for example that “polio” in goats means a vitamin deficiency disease, not the infectious disease that humans get. And I have learned that dogs don’t have blood types, so any dog can donate blood to any other dog. That’s good to know, but as a skeptic there are a few things on those shows that I question. I have frequently seen TV veterinarians use laser therapy to speed wound healing from both injuries and surgical incisions. I kept wondering “Is that for real? Is it based on science or superstition?” I decided to look into the evidence.
What are Lasers?
“Laser” stands for “Light Amplification by Stimulated Emission of Radiation.” Einstein established the theoretical foundation in a 1917 paper, and the first laser was built in 1960. Lasers emit coherent light that can be tightly focused and has a limited spectrum, emitting a single color of light. Output can be continuous or pulsed. A laser that produces light is technically an oscillator rather than an amplifier, and it has been suggested that the acronym LOSER — Light Oscillation by Stimulated Emission of Radiation — might have been a more correct acronym, although it is apparent why that didn’t catch on! Today, lasers are everywhere and have many applications, from bar codes to laser printers, from surgery to welding, from entertainment to law enforcement, from DVD players to laser pointers (great for giving lectures and for playing with cats). There are many types of lasers; they can use visible light or other electromagnetic frequencies, from infrared to X-rays and even gamma rays.
Lasers have many applications in medicine. In surgery, they can cut more precisely than scalpels and can stop bleeding. In cancer treatment, they have various uses that are supported by good scientific evidence. The evidence is not so clear for low-level lasers (cold lasers), which have been used for wound healing, smoking cessation, tuberculosis, temporomandibular joint (TMJ) disorders, carpal tunnel syndrome, fibromyalgia, osteoarthritis, rheumatoid arthritis, and much more. Cold lasers are even applied to mythical acupuncture points as “laser acupuncture.”
Veterinary Use
Lasers are widely used by veterinarians to facilitate wound healing, reduce inflammation, and treat musculoskeletal pain. Some veterinarians advocate laser treatment of allergic skin disease, infections, and envenomation (the process by which venom is injected by the bite or sting of a venomous animal); some claim they improve general health and enhance immune function and can even reverse “Qi-stagnation,” whatever that is! Veterinary studies are sparse, poorly designed, and the results are inconsistent. There are no systematic reviews of clinical trials validating laser therapy for specific indications in animals.1
A correspondent in Kentucky tells me his veterinarian pushes laser therapy for animals with sore joints, charging $240 for five treatments. Each treatment lasts 10 minutes. He says his dog hates going to the vet, and he wonders if there aren’t better ways to apply heat at home for longer periods.
Evidence in Humans
There are far more studies in human medicine than in veterinary medicine. Hundreds of systematic reviews are available for specific conditions, but the results are inconsistent. In vitro studies demonstrate effects on tissues, and there are anecdotes galore, but the clinical studies in humans are far from convincing.
Stephen Barrett reviewed low-level laser therapy (LLLT) devices on Quackwatch.2 More than 40 of these devices have been cleared by the FDA under the Class II description of “lamp, nonheating, for adjunctive use in pain therapy” and as infrared heat lamps. Dr. Barrett concluded:
The scientific consensus is that no LLLT has been proven more effective for pain than standard forms of heat delivery. Some benefits have been reported, but the studies have been too small and/or too short to draw firm conclusions. The best-designed study of diabetic patients with sensory nerve impairment of the feet found that 90 days of Anodyne therapy at home brought about no more improvement in peripheral sensation, balance, pain, or quality of life than sham therapy.
He reported various government enforcement actions against manufacturers for illegal marketing claims; in one case, three individuals pleaded guilty of conspiracy and went to prison. Several insurance companies including Aetna, CIGNA, and The Center for Medicare and Medicaid Services have reviewed the published evidence and explained why they don’t cover LLLT.
Aetna considers Class III laser and high-power Class IV laser therapy experimental and investigational for a long list of indications because there is inadequate evidence of effectiveness.3 They provide an exhaustive description of all the relevant published studies.
They report research on everything from carpal tunnel syndrome to knee osteoarthritis, from hair loss to obesity. A typical excerpt:
Although the results from large, uncontrolled, open trials of low-energy lasers in inducing wound healing have shown benefit, controlled trials have shown little or no benefit. The analgesic effects of low-energy lasers have been most intensely studied in rheumatoid arthritis. Recent well-designed, controlled studies have found no benefit from low-energy lasers in relieving pain in rheumatoid arthritis or other musculoskeletal conditions. Furthermore, although positive effects were found in some earlier studies, it was not clear that the pain relief achieved was large enough to have either clinical significance or to replace conventional therapies.
CIGNA concluded:4
Low-level laser therapy (LLLT) has been proposed for a wide variety of uses, including wound healing, tuberculosis, and musculoskeletal conditions such as osteoarthritis, rheumatoid arthritis, fibromyalgia and carpal tunnel syndrome. There is insufficient evidence in the published, peer-reviewed scientific literature to demonstrate that LLLT is effective for these conditions or other medical conditions. Large, well-designed clinical trials are needed to demonstrate the effectiveness of LLLT for the proposed condition.
The Centers for Medicare and Medicaid Services issued a Decision Memo5 saying:
CMS has determined that there is sufficient evidence to conclude that the use of infrared devices is not reasonable and necessary for treatment of Medicare beneficiaries for diabetic and non-diabetic peripheral sensory neuropathy, wounds and ulcers, and similar related conditions, including symptoms such as pain arising from these conditions … [therefore] The use of infrared and/or near-infrared light and/or heat, including monochromatic infrared energy (MIRE), is not covered for the treatment, including symptoms such as pain arising from these conditions, of diabetic and/or non-diabetic peripheral sensory neuropathy, wounds and/or ulcers of skin and/or subcutaneous tissues in Medicare beneficiaries.
The research is marred by inconsistency. The studies use different kinds of laser, different devices, different powers and wavelengths, different treatment protocols, and a variety of different indications. There are both positive and negative studies, and no replications to confirm results.
Are Class 4 Lasers Better?
Therapeutic lasers are classified as Class 1 to Class 4 depending on their potential for injury to eyes and skin.6 A watt is a unit of power defined as 1 joule per second; it is used to quantify the rate of energy transfer. Class 2 lasers produce 0–1 milliwatts, Class 3B lasers produce 5–500 milliwatts, and Class 4 lasers produce greater than 500 milliwatts. For comparison, the lasers used in surgery for cutting and cautery use up to 300 watts, which is 300,000 milliwatts. Class 4 lasers were designed for surgical applications, not for therapeutic use. They heat the tissues, can burn the skin, and can cause permanent eye damage, even from indirect exposure. They can ignite combustible materials, starting a fire. Damage can be limited by increasing the beam diameter, turning down the power, and keeping the device in constant motion.
This article appeared in Skeptic magazine 24.2
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Manufacturers of Class 4 devices who market them for therapeutic uses claim their devices work better because they use certain specific wavelengths, rapid pulses, and proprietary innovations. They are said to penetrate deeper into tissue (6 to 9 inches). A larger treatment head compresses superficial tissues, and a larger area of the body can be treated at once. They say the photons are absorbed by melanin, hemoglobin, oxyhemoglobin, and water. Energy generated by this process is felt as a soothing warmth. Light absorption stimulates cytochrome C to produce more ATP and free nitric oxide (a vasodilator) and reactive oxygen species, growth hormone, cellular proliferation, and mobility increase. This improves blood circulation and speeds the healing process. Marketers claim all this has been documented in the lab. Maybe, but others disagree,7 saying that 90 percent of the light energy is absorbed in the first centimeter. Even if the laboratory claims are true, that doesn’t mean there are significant clinical benefits to humans in the real world outside the lab. The evidence is lacking. There is no evidence that Class 4 devices produce better clinical outcomes than Class 3B devices.
The Richmar company, which sells 3B laser devices, has a webpage detailing “The Truth About Class 4 Lasers.” They explain:8
- Longer wavelengths do not equal deeper tissue penetration.
- The higher power output could result in tissue damage.
- They’re not a good fit for therapeutic use.
The LightForce website sells Class 4 devices. They describe “5 Painful Conditions Laser Therapy Can Help When Nothing Else Works:”9 tendinitis, plantar fasciitis, arthritis, TMJ syndrome, and carpal tunnel syndrome. Maybe lasers can help, but they don’t provide even a shred of evidence. Why should we believe their bald assertions? As Christopher Hitchens said, “What can be asserted without evidence can be dismissed without evidence.”
Bottom Line
The use of therapeutic lasers by veterinarians and medical doctors is not warranted by the existing scientific evidence. As the Mayo Clinic says, “the question of whether these treatments offer hope, or are merely hype and hokum, is unanswered.”10
More research is needed. 
About the Author
Dr. Harriet Hall, MD, the SkepDoc, is a retired family physician and Air Force Colonel living in Puyallup, WA. She writes about alternative medicine, pseudoscience, quackery, and critical thinking. She is a contributing editor to both Skeptic and Skeptical Inquirer, an advisor to the Quackwatch website, and an editor of sciencebasedmedicine.org, where she writes an article every Tuesday. She is author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon. Her website is SkepDoc.info.
References
This article was published on August 13, 2019.
A few references to some credible research in this area:
https://www.laserfocusworld.com/lasers-sources/article/16551613/lowlevel-light-therapy-photobiomodulation-takes-the-spotlight
And
https://www.wnycstudios.org/story/bringing-gamma-back
The field may be getting some serious scientists involved, finally.
Enjoy
Dr. Hall – thank you for publishing this article. A strong placebo effect has been demonstrated to occur in both pet owners and veterinarians, which has led to the widespread use of many unproven therapies. The pet owner truly believes the pet is better, and so does the veterinarian. Unfortunately, there is not a placebo effect for the dog or cat, so their condition persists. There are FDA approved medications for animals that do have proven efficacy, but not enough.
And last, please remember that “reality” shows like Dr. Pol are for entertainment only, and they may or may not show the level of care that is available in the majority of veterinary practices in the US.
Thanks again for a factual and science-based article.
Chuck Lemme, DVM
Good article, as always. thank you.
Dear Dr Hall, I apologise if I misunderstood you. I have no experience of cold lasers or LLLT and I suspect I never will have. Perhaps the way you phrased your conclusion is what confused me.
I think I understand how lasers work and I certainly have extensive personal experience of Class 4 lasers and their benefit to patients. I think one of the problems is that lasers are very expensive both to buy and maintain. They are very complex machines. For example the fractionated CO2 we use cost £60 000 to buy and costs £1000 a year to maintain. The laser I use in the private sector cost £110 000 to buy!
This limits their use to those people who can afford the purchase and running costs. Because all Class 4 lasers are inherently risky (to eyesight and fire risks etc) then laser practitioners need a sophisticated set up to use them. This includes the necessary protective eyewear etc. It is disingenuous of manufacturers of Class 3 lasers to dismiss Class 4 lasers on the grounds of lack of evidence. There isn’t any high quality evidence for any medical laser. There is however a wealth of anecdotal evidence, published articles in peer reviewed literature and thousands of patients who have clearly benefitted. How do I know this? Because I ask my patients.
In the UK in the NHS ,and in private clinics, there are considerable health and safety conditions that have to be met to use lasers. As a result of this companies have developed and marketed cheaper machines and sometimes clinics dupe patients by implying that IPL is a laser etc.
I am glad you quoted Hitch and reminded us all that what can be asserted without evidence can be dismissed without evidence. I also like Carl Sagan’s statement that extraordinary claims require extraordinary evidence. It is right and proper to be skeptical about novel medical or surgical treatments. One of the big problems in surgery is that it is very hard to do randomised controlled trials of surgical procedures as there are so many variables. As you know there are very few RCTs in surgery but none the less we still have to treat our patients. This means that usually we have to use level 3,4 or 5 evidence. I don’t think we will ever have level 1a or 1b evidence in burns or laser surgery. That means in my clinical practice I have to do my best for my patients by : audit of my practice, research what I can, ask experts, keep up to date with the literature, read the journals and attend conferences and symposiums. The most important thing though is to ask the patients what worked and what didn’t and be honest about one’s own experience or lack of.
Kindly regards
Bruce
Thank you both doctors Hall and Philp.
I’ve learned something from both of you.
Apples and oranges. I did say lasers had many applications in medicine, but that’s not what this article was about. When I concluded “The use of therapeutic lasers by veterinarians and medical doctors is not warranted by the existing scientific evidence.” I was referring to the use of cold lasers and LLLT for the conditions cited in my article. If I had specified that I meant THIS use of lasers rather than THE use of lasers for any reason, I think we would have no cause for disagreement.
Hi Dr Hall. I strongly disagree with the conclusions of your article.
There are three targets (chromophores) in human skin; melanin, haemaglobin and water. The lasers designed to target these chromophores are Q switched, pulse dye PDL) and carbon dioxide (CO2) respectively. For example PDL uses a 595 nm wavelength of light with pulse durations in a millisecond range and fluency of 7-12 J/Cm2). The wavelength of a laser is deliberately chosen to match the peak absorption of the target chromophore. Q switched lasers have a microsecond pulse duration and the chosen wavelength matches the peak absorption of melanin. Because melanocytes have such a broad absorption spectra depigmentation or hyperpigmentation is a potential complication of all lasers. CO2 lasers target water and can ablate anything containing water. This includes skin, skin lesions, scars or even wood. For example intractable viral warts can be ablated. The downside of traditional CO2 ablation is scarring. Fractional CO2 however results in minimal scarring as the holes are so tiny.
Evidence to support a contrary view are as follows: Laser treatment of unwanted hair
(Laser Hair Removal – LHR) is now a world wide billion $ industry. Q switched lasers target the melanin in the outer root sheath of the hair follicle. The heat resulting kills the hair stem cells in the bulge region and in the hair bulb. Hairs are only susceptible to damage in their growing phase and human hair growth is not synchronous, with only 10% of hairs actively growing at any one time, hence only 10% of hairs can be killed during each treatment. There are numerous publications on LHR – try searching for David Gault, the plastic surgeon who pioneered laser hair removal. I gave the first presentation ever on laser hair removal in 1994. The effect of LHR on patients lives can be dramatic. Some of my patients were virtually house bound recluses before treatment. After 8 treatments (each treatment reducing hair density by ~10%) they were able to socialise, get jobs and had massively improved self esteem. Alternative light based therapy includes Intense Pulsed Light (IPL) and Photo Dynamic Therapy (PDT). IPL is an excellent treatment for facial rosacea. PDT combined with Metfix can treat superficial basal cell carcinoma, actinic keratoses, and viral warts.
Lasers have a big role in the management of congenital skin lesions. These lesions often have profound adverse psychosocial effects. For example:
The treatment of choice for Port Wine Stains (PWS) is Pulsed Dye laser. For the vast majority of patients Pulsed Dye Laser (PDL) is the only treatment option. For most PWS there are no surgical or other non-surgical options. There are now numerous publications in the world literature supporting this treatment modality. The theory of extended photo-thermolysis (Anderson & Parrish) is very plausible. The target chromophore is oxygenated haemoglobin. The red blood cells absorb the laser light and heat up and this heat damages the vascular endothelium. This results in inflammation and then fibrosis and closure of the vessel. The same process occurs in treatment of telangectasia (spider navi), facial erythema and burn scar erythema.
Similarly the best treatment for Congenital Melanocytic Naevi (CMN) not amenable to surgical excision is combination laser therapy, especially on the face and exposed areas of skin where scars are cosmetically disastrous. Depigmentation is achieved using Q switched lasers ( such as the ruby laser) which have micro second pulse durations. The chromophore in this case is the melanin in melanocytes, the pigment making cells found in the epidermis and hair follicles. The light/tissue interaction with Q switched lasers is photo-acoustic and the laser light shatters the pigment and kills the melanocytes in the lesion. If the CMN is raised then CO2 laser ablation can flatten the lesion. Benign facial moles can also be treated with C02 and ruby laser. Q switched lasers targeting ink pigment is the basis of laser tattoo removal. Tattoo removal is also a multi million dollar industry. Another disfiguring condition is sebaceous naevus. The lesions, which can be extensive, can be smoothed flat with an ablative CO2 laser.
There is now extensive evidence for the benefit of lasers for scar management, especially in burn scars. Scarring in burns is inevitable if there is a dermal injury. Such scars have enormous adverse functional psycho-social and cosmetic outcomes. In our burns service ( St Andrew’s Centre, Broomfield Hospital, Chelmsford, UK) ,which is the largest in the UK , we use lasers for all burn scars including in children. The major advance in CO2 laser treatment was the development of fractionated CO2. These lasers deliver light with tiny spot sizes and the light is delivered using a computer generated scanner. The tiny holes created heal rapidly by edge re-epithelialisation. Lasers can address 3 aspects of scarring- persistent erythema (scar redness), dyschromia (hyper or hypo pigmentation, a significant problem in patients with pigmented skin) and scar contracture and tightness. We use a Pulsed Dye Laser (PDL) for redness and scar itch, a Qswitched laser (Ruby laser and now more modern lasers) for scar dyschromia/unwanted pigmentation and a fractionated CO2 laser combined with topical steroid for scar contracture. The results have been amazing and we now offer combination laser therapy to all our burn scar patients (ie everyone). We offer treatment to children as young as 1 years old. We have children as young as 5 years old having treatment as out patients. In children and adults 90% of patients have treatment under local or topical anaesthesia. Patient reported outcomes have been uniformly good to excellent. Complication rates are minimal. The tiny wounds from fractional CO2 treatment heal within 48 hours. Because of the limited penetration of fCO2 we combine it with micro-needling. Our physiotherapy and occupational therapists believe the results of combination laser therapy to have been incredible. For example patients report scar contracture improvement occurring with even one treatment or even during the treatment. We now start laser treatment as soon as the wounds have healed. We used to start treatment at 6 weeks post burn but now offer it as soon as wound healing has occurred. Laser therapy can be combined with silicon gel treatment and pressure garments.
The pioneers of laser treatment of burn (and other) scars in the UK are Max Murrison ( a plastic surgeon in Swansea, Wales) and Tapan Patel (A dermatologist, Phi clinic, Harley St, London). A Medline search for their names, or for laser treatment of burn scars, will reveal numerous publications on the benefit of laser therapy for scarring.
About 90% of the work of our laser service is scar treatment- our service runs 10 hours a day, 5 days a week (up to 20 patients a day) and currently we are so busy that we are finding it difficult to start therapy as early as we would wish.
Indeed the indications for laser treatment in dermatology and plastic surgery are numerous. The use of fractionated CO2 laser for facial rejuvenation is one example. Another is the treatment of hypertrophic scars (red, raised and persistently lumpy scars). Another is post mastectomy and DIEP flap reconstruction- hair removal on the transposed abdominal flap and fCO2 for the scars on the breast and abdomen. Another is laser ablation of metastatic malignant melanoma.
In my own experience as a consultant laser surgeon and burns/Plastic surgeon since 2003 I believe that combination laser treatment of burn scars has been revolutionary. Laser therapy is also the treatment of choice for PWS and many other cutaneous congenital and acquired lesions.
Kind regards
Bruce Philp MA BMBCh FRCS FRCS (Plast)
Consultant Burns & Plastic surgeon & Director St Andrew’s laser service
Chiropractors in Northern Virginia advertise laser treatment
Hi Dr Hall. I strongly disagree with the conclusions of your article. Evidence to support a contrary view are as follows: Laser treatment of unwanted hair is now a world wide billion $ industry. There are numerous publications – try searching for David Gault, the plastic surgeon who pioneered laser hair removal. I gave the first presentation ever on laser hair removal in 1994. The effect on patients lives can be dramatic. Some of my patients were virtual house bound recluses before treatment. After 8 treatments (each treatment reducing hair density by ~10%) they were able to socialise, get jobs and had massively improved self esteem.
The treatment of choice for Port Wine Stains is Pulsed Dye laser. There are numerous publications in the world literature supporting this treatment modality. The theory of extended photo-thermolysis (Anderson & Parrish) is very plausible. Similarly the best treatment for Congenital Melanocytic Naevi is combination laser therapy, especially on the face and exposed areas of skin where scars are cosmetically disastrous.
There is now extensive evidence for the benefit of lasers for scar management, especially in burn scars. Scarring in burns is inevitable if there is a dermal injury. Such scars have enormous adverse functional psycho-social and cosmetic outcomes. In our burns service ( St Andrew’s Centre, Broomfield Hospital, Chelmsford, UK) ,which is the largest in the UK , we use lasers for all burn scars including in children. Lasers can address 3 aspects of scarring- persistent erythema (scar redness), dyschromia (a significant problem in patients with pigmented skin) and scar contracture and tightness. We use a Pulsed Dye Laser (PDL) for redness and scar itch, a Qswitched laser (Ruby laser and more modern lasers) for scar dyschromia/in wanted pigmentation and a fractionated CO2 laser combined with topical steroid for scar contracture. The results have been amazing and we now offer combination laser therapy to all our burn scar patients (ie everyone). We offer treatment to children as young as 1 years old. We have children as young as 5 years old having treatment as out patients. In children and adults 90% of patients have treatment under local or topical anaesthesia. Patient reported outcomes have been uniformly good to excellent. Complication rates are minimal. The tiny wounds from fractional CO2 treatment heal within 48 hours. Our physio and occupational therapists believe the results of combination laser therapy to have been incredible. For example patients report scar contracture improvement occurring with even one treatment or even during the treatment. We now start laser treatment as soon as the wounds have healed. We used to start treatment at 6 weeks post burn but now offer it as soon as wound healing has occurred.
The pioneers of laser treatment of burn and other scars in the UK are Max Murrison ( a plastic surgeon in Swansea, Wales) and Tapan Patel (A dermatologist, Phi clinic, Harley St, London). A Medline search for their names or for laser treatment of burn scars will reveal numerous publications on the benefit of laser therapy for scarring.
About 90% of the work of our laser service is scar treatment- our service runs 10 hours a day, 5 days a week (20 patients a day) and currently we are so busy that we are finding it difficult to start therapy as early as we would wish.
Indeed the indications for laser treatment in dermatology and plastic surgery are numerous. The use of fractionated CO2 laser for facial rejuvenation is one example. Another is the treatment of hypertrophic scars (red, raised and persistently lumpy scars). Another is post mastectomy and DIEP flap reconstruction- hair removal on the transposed abdominal flap and fCO2 for the scars on the breast and abdomen. Another is laser ablation of metastatic malignant melanoma.
In my own experience as a consultant laser surgeon and burns/Plastic surgeon since 2003 I believe that combination laser treatment of burn scars has been revolutionary.
Kind regards
Bruce Philp MA BMBCh FRCS FRCS (Plast)
Consultant Burns & Plastic surgeon & Director St Andrew’s laser service
Good article by Dr. Hall, as usual. These often seem like fringe treatments, which common sense would say not to spend money on, but who wants to argue with your doctor/vet? Well, I do–as a confirmed skeptic, son of a veterinary professor, and growing up in an arguing family of six (the others were usually wrong, especially you, little brother)–but I understand those who do not.
The articles could include possible actions at the end, like:
* send/present a copy of this article to doctors/veterinarians who suggest this treatment
* if you’re presented with this topic, tell the doctor/vet, you need to research it, with the article listing research sources (I know this is the same as a bibliography, but make it more explicit).
Perhaps an article on how to research a topic might be useful, both for skeptics and for skeptics to present to others. Many people in the academic world take this knowledge for granted–but it’s not.