What is photobiomodulation therapy?
Photobiomodulation therapy (PBMT) uses red/near-infrared light to produce a clinical effect through the non-thermal interaction of monochromatic radiation with a target site. PBMT helps to modulate cellular functions, upregulating the production of adenosine triphosphate (ATP), nitric oxide (NO) and reactive oxygen species within cells. This can alter gene transcription and increase cell proliferation, cellular motility and growth factor production. A wide range of effects are attributed to PBMT, including stimulating tissue healing, analgesia and reduced inflammation. Additionally, it has a non-invasive nature combined with a lack of adverse effects.
Historically, PBMT has also been referred to as cold lasers or low-level laser therapy, to contrast with surgical lasers. Currently applied Class IV therapy lasers, also called high-power laser therapy, allow the delivery of between 500mW and 60W, which permits targeting deeper tissues, expanding the range of possibilities for this therapy. A consensus was then formed around the term PBMT, which better encompasses the complex mechanisms involved.
Applications of photobiomodulation
The role of PBMT in orthopaedics, rehabilitation and sports medicine is well established. In dogs, it has been described in the management of canine elbow osteoarthritis or during the recovery period after spinal decompression surgery. There are, however, many potential applications of PBMT in other areas of medicine, from surgery to dermatology, wound healing, cardiology, oncology and aesthetic procedures.
This potential, represented by the increasing number of reports on the potential uses of PBMT, indicates that there are many conditions in which vets should consider using it as a treatment or as a part of the treatment protocol. In addition to providing a better service to patients and improving treatment outcomes, including PBMT in an expanded range of interventions allows for a better return on investment in laser equipment.
There are many conditions in which vets should consider using it [PBMT] as a treatment or as part of the treatment protocol
However, calculating and selecting proper treatment parameters for specific conditions can be challenging, particularly when presented with a wide range of patient sizes, body conditions, coats and colours. Although it can be done, having software such as the Companion SmartCoat assisting in setting adequate treatment parameters is invaluable.
Case studies
The author’s practice exclusively serves a large population of police working dogs. Unsurprisingly, the majority of the work is sports medicine and rehabilitation-related and this was the initial motivation for acquiring laser equipment. However, working dogs are still dogs, and all other diseases and conditions also occur. The laser equipment comes with several pre-programmed treatment protocols, and by exploring them, the practice has expanded its possible uses of PBMT. The laser is currently the most used equipment in the practice – PBMT is used as the single treatment or part of the treatment protocol for managing diarrhoea, gingivitis, wounds, otitis, aural haematoma and lick granuloma, and for pain management, particularly post-surgical pain.
Management of chronic idiopathic large bowel diarrhoea
The practice set up a couple of studies to assess the impact of PBMT in treatments, beyond the positive empirical effect that was observed. The first case study evaluated the use of PBMT in the management of chronic idiopathic large bowel diarrhoea compared to a control group (receiving psyllium husk) (Alves et al., 2022). Although PBMT has been described as having a significant positive effect on disease progression in mice with induced colitis, its influence in cases of naturally occurring disease was still not determined (Zigmond et al., 2014).
Chronic inflammatory enteropathies are considered the most common cause of chronic gastrointestinal disorders in dogs. Chronic idiopathic large bowel diarrhoea may occur in dogs without any evidence of inflammation and is frequently observed in working and sporting dogs; it may be linked to their high drive, excitable nature and stressful or competition events. The clinical signs that were considered were low body weight, a body condition score (BCS) less than four, a frequency of defecation of more than three times a day, soft or liquid stool, excess faecal mucus and difficulty maintaining a good body condition score, either continuously or intermittently. Patients with other illnesses were excluded.
Although an improvement was observed in both groups, animals treated with PBMT showed greater improvements in body weight and body condition scores
After selection, 15 dogs were assigned to a control group (CG) and 15 to a treatment group (TG).
Patients in the CG received four tablespoons/day of psyllium husk for one month. They were submitted to a sham laser therapy session on the same days as the treatment group. Patients in the TG received PBMT, with treatment parameters based on the set protocol determined with the equipment’s software. Three sessions were conducted in week one (one every other day), two sessions in week two (two days apart) and a single session in week three. A canine IBD activity index (CIBDAI) score and BCS score were collected on days 0, 8, 15 and 30. On the same days, patients were weighed. A daily faecal scoring log using the Bristol scoring system was maintained throughout the 30 days (Alves et al., 2022).
On day 0, 14 dogs defecated more than three times a day, 15 had a Bristol stool score corresponding to diarrhoea and 23 had a low BCS (of less than four), with no significant differences being observed between groups. While there were no significant differences in the appearance of a first episode of diarrhoea (12.6 days for CG and 12.3 days for TG), an increased time of appearance of the second episode of diarrhoea was observed (16.6 days for CG versus 23.6 days for TG) (Figure 1). The Cox regression results showed that treatment significantly influenced the appearance of diarrhoea episodes, with the CG showing a 4.5-fold probability of experiencing the event compared to the TG. In addition, although an improvement was observed in both groups, animals treated with PBMT showed greater improvements in body weight and body condition scores. PBMT significantly improved clinical signs of chronic inflammatory large bowel diarrhoea and frequency of diarrhoea episodes.
Reduction in gingivitis
In the second study, the effectiveness of PBMT in reducing gingivitis following a professional dental prophylaxis was studied. Forty-seven dogs were included in this study, with a periodontal disease grade of one or two, after screening our population of police working dogs (Alves et al., 2023). Dental prophylaxis and grading on day 0 were conducted under general anaesthesia. Each patient’s mouth was divided into left and right halves and graded individually for gingivitis and calculus. The left side was treated with dental prophylaxis only and served as a control group (CG).
In addition to dental prophylaxis, the right side received a single session of PBMT (PG). Follow-up observations were conducted on days 1, 3, 8 and 15 to determine a gingivitis index. While no differences were observed on treatment day between halves, the side treated with PBMT showed significantly lower gingivitis scores from day 1 to day 15 (Alves et al., 2023).
Although it was not evaluated, as a known effect of PBMT is analgesia, it was assumed that PBMT also improved patient comfort. Further, although not tested in this study, PBMT is used to treat higher grades of periodontal disease and other oral treatments, as it promotes tissue healing and oral comfort.
Conclusion
From a clinician’s perspective, laser equipment should be incorporated into your practice for several reasons:
- PBMT has a wide range of effects, including the stimulation of tissue healing, analgesia and reduced inflammation
- It is a non-invasive procedure, with a lack of adverse effects and very few absolute contraindications
- By expanding the number of procedures in which the laser equipment is used, an increase in return on investment is evidenced
- The Companion SmartCoat software is invaluable in setting adequate treatment parameters, particularly in new procedures. The newer laser models even include demonstration videos on how to conduct specific treatments (treatment area, treatment head and technique)
- By including PBMT in your treatment procedures, a better service to patients and improving outcomes can be evidenced
