Photobiomodulation therapy or “PBMT” sounds rather intimidating, but you might know it by its more well-known name: laser therapy. Despite sounding complicated, or perhaps scary, the practice of PBMT is nothing to be wary of – it is, in its simplest terms, a form of light therapy based on the photochemical process of photobiomodulation. Although the idea of laser-induced photobiomodulation is not a novel concept in veterinary practice, our knowledge of the therapy is constantly evolving. And we now know that PBMT has three core therapeutic outcomes for patients: the reduction of pain, the modulation of inflammation and the acceleration of tissue healing. But why is PBMT useful, what does it actually do and how can we maximise this therapeutic treatment in practice?
These questions were explored as part of Companion Animal Health’s education series, in a day-long conference on Sunday 11 September 2022 in Manchester, wherein Dr John Godbold, DVM, (Figure 1) and Emily Ashdown, RVN, explored “the art of laser therapy” for veterinary surgeons, nurses and technicians alike.
The science of laser therapy
PBMT is an invisible technique – you cannot see anything happening when you treat patients because the therapeutic process occurs under the surface of the skin. So how do we reassure clients that it works, and how do we get them to accept an invisible treatment in the first place? The art of communicating what PBMT is and why you are using it is, therefore, a fundamental skill for practitioners, says John. We have to be able to make the clients comfortable with the science of PBMT – so let’s dive into a quick overview of the science.
What happens under the surface?
The reason we should use the term “photobiomodulation” over “laser therapy” is very simple, argues John. This is because it “describes an interaction of light with the target tissue; a cascade of photon driven cellular and tissue effects”, and we must think in these terms when explaining what happens under the surface during PBMT. Lasers project a beam of light that penetrates deeply into the tissues, stimulating the cell membrane and cellular organelles that harness the light energy.
[PBMT] produces a non-invasive non-pharmacological reduction in pain, modulation of inflammation and acceleration of healing
The primary target, or “chromophore”, for PBMT is the photoreceptor cytochrome C oxidase, which is bound to the inner membrane of the powerhouse of the cell: the mitochondria. On the cellular level, the absorption of light by the chromophore increases the release of adenosine triphosphate (ATP), reactive oxygen species and the homologation of nitric oxide. Overall, says John, this photochemical reaction induces metabolic activity and triggers endocrine and kerocrine signalling within and between cells (Table 1), which, on the tissue and organism level, produces a non-invasive non-pharmacological reduction in pain, modulation of inflammation and acceleration of healing.
|Reduction of pain||Modulation of inflammation||Acceleration of soft-tissue healing|
|Release of endogenous opioids|
Suppression of nociceptors (causing a “neuroblockade”)
Increased free nitric oxide locally alters the nerve stimulation threshold and suppresses depolarisation
|Release of histamines, stimulating vasodilation|
Free nitric oxide promotes oxygen and nutrient transport and angiogenesis
Increases vascular permeability, facilitating leukocyte and macrophage activity to break down damaged tissue and bacteria
Inhibition of inflammatory prostaglandins
Activation of lymph drainage system
|Increases ATP production, accelerating metabolism|
Increase in pro-healing cytokines
Stimulates fibroblast development and migration
Stimulates collagen production and deposition
To summarise, ATP production drops when we have damaged or dysfunctional tissue. So, by applying a therapeutic dose of light to injured tissue we induce a cellular response that is mediated by mitochondrial mechanisms. “We’re not creating supercells,” explained Emily, “we’re not creating anything that the cell is not capable of doing – all we’re doing is increasing that [ATP] level back up to its normal function.” This enhances the environment for cells to repair and regenerate. For clients, we can reduce this information to three principles, says John: “It reduces pain, modulates inflammation and lets healing occur more quickly.”
What else do clients need to know about PBMT?
On top of a basic understanding of the science of PBMT, clients will likely ask about the safety of pets undergoing treatment and the evidence showing that the “invisible” treatment truly works. All of this, says John, is available in the literature. Recently, the evidence for PBMT has grown and continues to grow, with research showing, for example, improved lameness scores and reduced medication requirements in dogs with naturally occurring elbow arthritis after a period of PBMT (Looney et al., 2018). You only have to do a quick search to find a wealth of evidence, says John.
As with any laser-based treatment, there are risks if the laser is used improperly. But proper and regular training on how to use the device safely makes these minimal
Furthermore, in regard to safety, human patients have described laser therapy as providing a “pleasant warming sensation”, which John equates to “being in a warm shower”. And with the release of endorphins, the rise in systemic serotonin levels and the relaxation of muscles as a result of the therapy, PBMT can be a very pleasurable experience. However, as with any laser-based treatment, there are risks if the laser is used improperly. But proper and regular training on how to use the device safely makes these minimal. Monitoring the patient’s skin and fur temperature using a “trailing finger” technique and ensuring that all individuals – practitioner, patient and owner alike – are wearing appropriate wavelength-specific goggles are essential actions to combat the associated risks.
The art of laser therapy for practitioners
“To effectively treat patients,” states John, “we’ve got to be sure that enough photons actually penetrate to our target tissue.” Due to this, practitioners need to consider two key parameters for maximising the effects of PBMT.
- Energy density (J/cm2). Also known as the dose or “fluence”, energy density changes depending on the target of PBMT treatment. For example, you need to consider whether the target tissue is superficial (“if I can see it, it’s superficial,” says John) or deep tissue (musculoskeletal or in the abdomen/thorax). Large animals and equine patients will also need a larger dose
- Power density (W/cm2). Because not all tissue is the same, different tissue types do not respond to PBMT equally – mitochondria-rich tissue will absorb photons more easily than tissue with fewer mitochondria. Factoring in power density, technically termed “irradiance”, helps adjust treatment to match tissue type through consideration of power of the light per areas of treatment
Other parameters such as pulse mode, duration of treatment, hand-piece selection, preparation of patient, training, having a quiet and comfortable position/place for treatment, evaluating records and patient progress, consideration of referred pain and compensation, and client communication also play a part in the successful management of PBMT cases, observed John. For delegates attending the event, a thorough breakdown of these parameters, hands-on experience and a wealth of practical tips and tricks to maximise treatment results (Figure 2) was delivered by the expert speakers.
Choosing which patients to treat with PBMT can be a tough decision, especially when there are many contraindications, such as malignancies, active bleeds and pregnancy, that have been passed down over the years. However, what we usually consider as contraindications for PBMT don’t always make sense and aren’t always evidence-based, observed both John and Emily. In fact, beside direct or reflected beam exposure to the retina, John declared that “there are no other absolute contraindications” for PBMT. Instead, the practitioner should give special consideration to the “risk or perceived risk” of each individual situation. For example, “in terminal patients entered into hospice care when our only goal is reducing pain, I submit that we ought to be using laser therapy to reduce the pain,” argues John.
Beside direct or reflected beam exposure to the retina, John declared that ‘there are no other absolute contraindications’ for PBMT
Veterinary nurses and the power of marketing
Alongside treatment itself, Emily explained that there is another way for veterinary nurses to get involved in PBMT – marketing. Educating clients is a fundamental part of laser therapy and there are some simple but effective ways of providing information while marketing this treatment, the most effective of which is the power of social media. Clients love taking pictures of their pet in “doggles”, or “moggles” for our feline friends, so capitalise on this. And Emily reminds, “Don’t forget to take videos and photos of your cases, before and after – it’s amazing how much a difference even one session can make, and videos are the best way of capturing that.” After all, seeing is believing.
Why is PBMT useful in veterinary practice?
But you may be asking why is all of this important, and why is it useful to me? Well, Emily explained that “a lot of traditional methods of pain management are very systemic in their approach. But this means that you’re not treating the source of the pain”; instead it’s treating the symptoms systemically. PBMT, on the other hand, is direct and specific about where it is targeting, while simultaneously producing more immediate relief than traditional methods. Furthermore, while many people believe that PBMT is just for arthritic joints and tissue injuries, it’s actually perfect for so much more. Any form of pain or inflammation, and for any case where you need to help the healing process along, can benefit from PBMT. It’s important, therefore, to “think of [PBMT] as a tool” instead of “a treatment for a specific modality”, says Emily.