What Is Photobiomodulation Therapy?

Photobiomodulation is an innovative therapy that can increase the comfort of patients and enhance your practice’s multimodal approach to a variety of clinical cases. Knowing how this therapy works and when to best use it is key to its successful implementation.

Some Tips and Considerations

Therapeutic laser therapy is becoming an increasingly available option that veterinary practices can offer their patients. It has many beneficial uses in veterinary patients, including providing analgesia as part of a multimodal pain management plan, promoting wound healing, and reducing inflammation. With the proper training, it is a relatively easy and noninvasive therapy that can be added to a number of treatment protocols.

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Properly trained technicians can take on laser therapy
appointments, if state regulations permit, freeing
veterinarians for other tasks.

The therapeutic lasers most commonly used in clinical practice work via a process called photobiomodulation—previously known as low-level light/laser therapy (LLLT). Photobiomodulation therapy (PBMT) uses nonionizing light sources in the visible and infrared spectrum, including lasers, LEDs, and broadband light.

Although the term “photobiomodulation” was first proposed in a publication in 1997, it was more widely adopted only recently, and is often still used interchangeably with LLLT. In 2014, the North American Association for Light Therapy and the World Association for Laser Therapy met to update laser therapy nomenclature, and in 2015, photobiomodulation was officially accepted as a Medical Subject Headings (MeSH) term by the National Library of Medicine.

Photobiomodulation is an innovative therapy that can increase the comfort of patients and enhance your practice’s multimodal approach to a variety of clinical cases. Knowing how this therapy works and when to best use it is key to its successful implementation.

What Is Photobiomodulation?

When a laser or other form of light within a specific spectrum is applied to tissue, it causes chemical and biological reactions within the tissue that can be both stimulatory and inhibitory, depending on the cellular process. The idea that light can be used for healing is ancient; early Greek physicians observed that exposure to light seemed to help wounds, and sunlight has been noted anecdotally as a healing treatment for centuries.

In the late 1800s, physicians began using red and blue light to treat conditions like Lupus vulgaris, and in 1903, Niels Ryberg Finsen won a Nobel Prize for demonstrating that concentrated rays of sunlight can stimulate wound healing and kill bacteria. However, because the mechanisms of these actions were not well understood, therapeutic light therapy was, for the most part, excluded from mainstream medicine. That is, until lasers were invented in the 1960s and revolutionized the field.

Although it is a household term now, the word “laser” is an acronym for Light Amplification by Stimulated Emission of Radiation. Lasers are designed to emit and amplify light at specific wavelengths, producing a tight beam of radiation. A laser is essentially a sealed tube where an energy source (the power cord, in the case of most therapy lasers) is applied to a substance contained within the laser between two mirrors. Depending on the laser’s intended use, this substance could be a gas (like carbon dioxide or argon), a liquid, or a solid crystal. The crystal aluminum gallium arsenide is often used in therapeutic lasers. When energy is applied to this substance, it releases light particles called photons, which are amplified by the mirrors at either end of the tube and create a focused beam of light.

This beam of light then moves along a fiber optic cord to the handpiece, which is applied to the patient. Lasers are able to produce light that is a uniform, single wavelength that can penetrate tissues. Lasers can deliver continuous or pulsed beams of light.

The FDA divides lasers into four classes based on their power. Class III and IV are the most common lasers used in veterinary practice.

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How Does Photobiomodulation Work?

Photobiomodulation uses light photons to target water, hemoglobin, and cytochrome C oxidase at the cellular level in the bloodstream and mitochondria. This stimulates cellular respiration and ATP generation and can also promote the formation of enzymes that fight against oxidative stress, like superoxide dismutase. As a result, a number of secondary effects occur, including:

  • DNA and RNA synthesis
  • Fibroblast, macrophage, and lymphocyte activation
  • Release of growth factors and neurotransmitters
  • Vasodilation and increased
    blood flow
  • Collagen synthesis
  • Angiogenesis
  • Increased oxygen and nutrient availability leading to increased protein synthesis
  • Improved cell membrane permeability
  • Removal of cellular debris
  • Release of endogenous endorphins
  • Increased production of anti-inflammatory mediators

All of these effects contribute to better wound healing, decreased inflammation, and improved analgesia.

mainillustration.pngJennifer Johnson, VMD, CVPP, is the immediate past president of the International Veterinary Academy of Pain Management and a member of the 2022 AAHA Pain Management Guidelines in Dogs and Cats task force. She noted that while photobiomodulation reduces inflammation and pain and speeds healing, knowing the appropriate dose is important in order to achieve the desired effects of the therapy. “Over recent years, appropriate wavelengths and doses have been published, which demonstrate efficacy,” she said. It’s important for veterinarians to be aware of recommended doses for conditions.

But in terms of photobiomodulation’s pain management possibilities, Johnson said, “Using laser therapy in general practice as part of a multimodal pain management program is becoming standard of care in veterinary practice.”

What Conditions Can Photobiomodulation Treat?

Photobiomodulation therapy can be used in many conditions to increase healing, decrease inflammation, and achieve better pain management for patients. According to Johnson, “When PBMT is combined with pharmacologic pain management, there can be a reduction in the dose of medications necessary.”

PBMT can be useful in the following conditions:

  • Sprains and some fractures
  • Wounds, abrasions, and hematomas
  • Ligament and tendon injuries
  • Inflammation in joints, ears, muscles, and skin
  • Joint injuries
  • Myofascial trigger points, pain points, and deep-tissue acupuncture points
  • Chronic and acute pain
  • “Hotspots” and lick granulomas
  • Postoperative healing

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“Using laser therapy in general practice as part of a  multimodal pain management program is becoming standard of care in veterinary practice.”

—JENNIFER JOHNSON, VMD, CVPP

PBMT can also be used for many chronic conditions in dogs and cats, including osteoarthritis, stomatitis, hip and elbow dysplasia, intervertebral disk disease, feline asthma, otitis, and chronic pain.

For canine patients, Johnson noted, “More studies have been published providing good evidence for the use of PBMT in dogs—most recently showing positive effects in the treatment of colitis in dogs and as a treatment for osteoarthritis pain in dogs.”

“Any patient with inflammatory conditions can be a good candidate, for example: dermatitis, cellulitis, gastroenteritis, pancreatitis, cystitis, arthritis, myositis,” said Johnson.

What Conditions Are Contraindicated?

PBMT is generally considered safe for a wide range of applications, but it can be harmful if used incorrectly. Johnson cautions it should never be used on or near the eyes. Both direct and reflected light exposures in the eyes can cause retinal damage, and eye protection should always be worn by both patients and practitioners.

Conditions where caution and special considerations are required include areas in which medications have been injected locally, cancer, pregnancy, open growth plates, and active hemorrhage. Johnson gave an example of when these special considerations come into play: “We always say use caution around obvious tumors, like, for example, dogs get an aggressive skin tumor called [a] mast cell tumor.” She noted that using PBMT judiciously means practitioners must understand what the treatment goals are. “And if I had an inkling or was worried, I wouldn’t do laser therapy on or around it [the tumor], but that wouldn’t preclude me from using it for the hips of this dog with osteoarthritis who happens to also have a skin tumor.”

The therapy should not be used on testicles or the thyroid gland. Areas of hyperpigmentation and tattoos should be monitored carefully to ensure they are not experiencing any heat or discomfort.

PBMT can be used near suture material and tissue adhesives as well as over orthopedic implants. However, if metallic implants are present, they will reflect photons from the light beam into the surrounding tissue. Because of this, the light beam should be angled away from the implant as much as possible and doses should be reduced.

In the past, antimicrobial infections have been considered a contraindication for PBMT, but some recent studies have shown that it may stimulate the immune system and help clear an infection faster. Photosensitizing medication is not considered a contraindication for PBMT, based on a 2014 review article that reported no adverse effects.

How Fast Does Laser Therapy Work?

How long and how often PBMT is used depends on the patient’s condition. “Acute conditions will respond quickly,” said Johnson, “sometimes with only one treatment.” She noted that acute otitis is one example where rapid improvement can be seen: “An ear infection in a dog can be treated to reduce the swelling, inflammation, and pain quickly.”

In general, acute conditions can be treated two to three times or more and should show a response after one to two treatments. For chronic conditions, a treatment plan should be made with the patient’s condition and the client’s capabilities in mind. Initially, patients may be treated daily or two to three times weekly, with a gradual tapering of sessions until maximum effect is achieved.

“Conditions like osteoarthritis can be treated chronically, and we often will start out with once-a-day treatment until there is improvement, then taper treatments slowly over time,” said Johnson. She pointed out that for many of the chronic conditions treated with PBMT, resolving the condition is not possible. In these cases, PBMT becomes an important tool that clinicians can use to alleviate discomfort, provide a better quality of life, and help their patients become more functional. “With conditions such as osteoarthritis, which have no cure, the treatment is aimed at reducing pain and improving quality of life.”

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Considerations for Using Laser Therapy in Practice

PBMT can be a valuable option for comprehensive, multimodal treatment plans for both acute and chronic conditions in dogs and cats. However, there are several factors to consider before adding laser therapy to your practice.

The first step, according to Johnson, is to do your homework. “Not all therapy lasers are equal,” she cautioned. “Just like with so many medical devices, there are many products available that profess to be effective but are probably not.” She suggests that a resource like Laser Therapy in Veterinary Medicine: Photobiomodulation, edited by Ronald J. Riegel and John C. Godbold, Jr., is a good place to start to become familiar with the ins and outs of laser therapy.

Another consideration is how you will integrate laser therapy into your practice, including pricing structure, staff training, client and veterinary team buy-in, and marketing. The location is also important—consider whether there is a dedicated area or room available for PBMT that is quiet, calm, and free of interruption where the patient can relax.

Johnson suggested initially adding PBMT as an adjunctive postoperative pain management strategy. She said, “If you’re a great surgeon, things are going to heal well, but [with PBMT,] they’re going to heal faster. And that’s really nice thing to be able to see quickly.”

PBMT provides an excellent opportunity for technician involvement, and time and investment are required for proper training on its use and safety. Properly trained technicians can take on laser therapy appointments, if state regulations permit, freeing veterinarians for other tasks. “PBMT has to be applied by trained staff in the office,” said Johnson, “and it can be totally [driven by] support staff and technicians.” She recommends the American Institute of Medical Laser Applications’ training courses for veterinary staff.

Holding a veterinary team training within your practice that explains how PBMT works and why it’s a good option for some patients can help the veterinary team develop consistent messaging when talking to clients. This time can also be used to present your practice’s simple core message about PBMT to the staff, which they can then convey to clients.

Finally, determine how and when information about PBMT will be presented to clients, and in what form. Clients may want to know how effective it is, what it will feel like to their dog or cat, and how long it will take to see results. It may be helpful to have answers and materials already prepared that can answer clients’ questions, assuage any concerns they may have, and set realistic expectations for therapy.

Johnson pointed out that, compared with 15 years ago when she first started using laser therapy, clients today are pretty savvy and likely have already heard of it. She’ll often tell clients that PBMT works to help cells that aren’t functioning their best get back up to their normal capacity. “It’s just adding to what you’ve already done, to make your outcomes that much better.” 

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Ingrid Taylor, DVM, is AAHA’s technical content specialist.

Photo credits: ©AAHA/Robin Taylor

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