Rufus R. Noble Simple Summary
Photobiomodulation, or light therapy, is used collectively for techniques where tissues are exposed to different kinds of light to promote healing. The list includes methods including lasers, Light Emitting Diode (LED) light Ultra and infrared light, and tanning beds. The primary reasons for using light therapy are neurological injuries, musculoskeletal conditions, wounds, and pain in animals. Despite its widespread use, there has yet to be any consensus on the best treatments for light therapy or its clinical effectiveness. The purpose of this review is to examine the evidence-based clinical effects of light treatments, with a particular focus on LED light and lasers used in dogs, horses, and cats. The comprehensive review of the literature identified some gaps in the scientific literature. The inconsistent results of studies and the unclear clinical application of these therapies are caused by the variety of treatment parameters utilized in the studies that were analyzed, including wavelength and laser class dosage, effect, and wavelength and how often and for how long the treatment is. Positive results have been observed in laser therapy; however, the studies that have been published also lack scientific validity on these treatments, with a risk of high or moderate bias.
Abstract
Photobiomodulation, also known as light therapy, is a term used for techniques wherein tissues are irradiated by different kinds of light in the hope of stimulating healing. While it is widely utilized, however, there isn’t a consensus about the most effective treatment methods for light therapy or its clinical effectiveness. A systematic review of the literature was conducted by searching for relevant research on light therapy in three databases that were published between 1980 and 2020. The possibility of bias in each of the articles was assessed. Forty-five articles fulfilled the inclusion criteria. Twenty-four of them were about dogs, one was about cats, and the remainder were about horses. The treatment options included neurologic and musculoskeletal disorders such as skin diseases and wounds, and discomfort. The review of the literature revealed conflicting research results and unclear applications for use in clinical settings. This could be explained by the range of parameters for treatment utilized in the search studies, like wavelength and laser class dosage, effect, and wavelength, in addition to the frequency and duration of the treatment. Although there were some positive effects documented for laser therapy, these studies were not scientifically rigorous on these treatments, with an increased or moderate risk of bias.
Keywords:
Light therapy ; laser therapy ; therapeutic laser ; cold laser ; low-level laser ; Photobiomodulation
- Introduction
Photobiomodulation, also called light therapy, is a common term for techniques where tissues are exposed to different kinds of light in order to stimulate healing. The list includes methods like lasers, Light Emitting Diode (LED) light Ultra and infrared light, as well as tanning beds. For humans, laser therapy has been employed for many years to treat diseases like depression, skin diseases, and painful wounds and to speed up the healing process of the musculoskeletal tissue. 1 ]. When it comes to animals, the most common reasons are musculoskeletal injury, neurological disorders, wounds, and pain 2 ]. Different sources of light have distinct characteristics. For instance, the light emitted from the laser is monochromatic, collimated, and has only one wavelength. This is different from ordinary light, which has many different wavelengths that are not collimated. One distinction between LED light and laser beams is that the laser’s light wavelengths are continuous and contain the wavelengths being in phase with space and time. The nature of light therapy isn’t fully comprehended. Photons, or light particles, are transmitted to the tissues. One theory for the method of action could be that the photons are absorbed into mitochondrial chromophores in cells, which trigger an image dissociation of inhibitory nitric oxide from the cytochrome C oxidase. This is followed by the growth of electron transport enzyme activity and ATP production, which are parameters associated with the proliferation of cells and tissue repair. 3 ].In practice, various kinds of light-emitting methods and sources are utilized with
multiple settings of wavelength, area of radiation intensity, and treatment duration. The majority of the time, they have a power of less than 50 J/cm 2 [ 3 ]. In recent years, more powerful lasers in class IV have been utilized for small animal training and can be as powerful as 15 watts/cm 2. Continuous lasers and pulsed lasers up to 300 milliwatts/cm 2 peak power are being used. Also adding confusion to any discussion on therapy lasers are the terms like the types of laser (CO2 HeNe, CO2, GaAs, and GaAlAs) and the use of single or multiple wavelengths and cluster probes that use various photon emitting devices within one unit. Although they are frequently utilized on animals, there isn’t a consensus about the most effective treatment procedures or their efficacy in the treatment of different conditions. Thus, the purpose of this review is to assess the evidence-based clinical benefits of light therapy, with a particular focus on LED light and lasers for dogs, horses, and cats.
- Materials and Methods
The general structure of this review was affixed with the Cochrane guidelines for how to conduct an organized review 4 As modified to be used by and adapted by the Swedish Agency for Health Technology Assessment and Assessment of Social Services (SBU) in its handbook on methodological procedures 5 ].
2.1. Review Topic/Research Question
To determine the scientific evidence that supports the clinical effectiveness of LED and laser therapy for animals, horses, and cats.
2.2. Search Strategy
Professional librarians searched for journals within these databases: Web of Science Core Collection, CABI, and PubMed (1980-2020) in August 2020. The keywords included terms that are relevant to cat or dog, or horse and vet medicine or veterinarian therapy * or treatment *. These keywords were paired with
words associated with light therapy, i.e., laser therapy, therapeutic laser low-level laser, photobiomodulation, and lighting emitting diode.
2.3. General Inclusion and Exclusion Criteria
The research included was to be original research that was released in a peer-reviewed journal during the period 1980 to 2020. The primary focus was on observational studies, which would include only one method of study in each treatment group was incorporated. Research studies may also be included if the study was a simulation of a clinical scenario. The subject species was to be either canine feline or equine
.Textbook chapter abstracts, conference proceedings, conference papers and opinion notes, reviews, cases, and articles (subject number 5) were not considered. Studies on the mechanism of action were also ruled out, along with those that utilized different treatments at the same time for each study group.
2.4. Study Selection and Categorisation
The screening process was conducted using the journal’s name, title, and publication or abstract. All cited articles were transferred into Endnote (X9.3.3 2018, 2018.) as well as duplicates eliminated. One author (DM) used the inclusion and exclusion criteria for every publication
.In the process of screening, articles with possibly relevant to the review and articles that described a specific kind of treatment in dogs, cats, or horses were deemed suitable to be read in full text. Therapeutic intervention is defined as an intervention designed to decrease the symptoms or severity of a medical disease. After the initial phase of screening, any articles considered to be relevant were read. In every study, the details were listed with templates that were modified following SBU 5 1) First author, the year of publication, study design and population of the study, the intervention, control results, and importance (external validity).
Assessment of bias risk (scientific high quality) of each paper was carried out according to the Cochrane study protocol. 4 ] and SBU [ 5 ] guidelines. The evaluation was based on the following criteria that were considered: the study’s design and statistical power, the treatment that was not planned, and the loss of follow-up kind of outcome assessment and relevance. When assessing observational studies, the risk for confounding risk was taken into consideration. The paper’s writing was carried out in accordance with a PRISMA 2022 checklist. This study was not recorded in PROSPERO since it isn’t intended for human health.
Results
An aggregate of 2581 abstracts Has been identified from three databases ( Figure 1 ). Duplicates were eliminated, and abstracts were reviewed by using inclusion criteria. A total of 125 articles were examined in detail. In relation to laser treatments for the musculoskeletal structure, 50 studies were identified, out of which 28 were studies on dogs, 22 of them were studies on horses, and none were cat-related studies. Thirteen of them fulfilled the criteria for inclusion. Concerning the effects of lasers on wound healing and skin, The abstracts included 44
Of which 32 were studies of dogs, 12 were studies on horses, and there was no study related to cats. Nineteen of them fulfilled the criteria for inclusion. For the treatment of pain using lasers, three of the studies dealt with dogs, one of them was about
cats and six research studies were conducted on horses. Seven of them were considered. From 20 studies on dogs that dealt with the use of lasers to treat various neurological disorders, only six studies were included. The study of a horse was recognized
. However, it didn’t satisfy the criteria for inclusion. The studies that didn’t meet the criteria for inclusion were case reports, reviews article, method papers, or used phototherapy as a part of a mix of treatments, making the assessment for phototherapy treatment as a singular treatment unattainable.
