Current Applications and Future Perspectives of Fluorescence Light Energy Biomodulation in Veterinary Medicine

Exposure to blue light reduces antimicrobial resistant Pseudomonas aeruginosa isolated from dog ear infections

Introduction

Pseudomonas aeruginosa is a leading cause of canine otitis externa. Enrofloxacin is often applied topically to treat this condition, although recalcitrant and recurring infections are common. There is evidence that exposure to blue light (400-470 nm) has a bactericidal effect on P. aeruginosa and other microorganisms.

Methods

In the present study, we tested the biocidal effect of blue light (375-450 nm), alone or in combination with enrofloxacin, against six isolates of P. aeruginosa from dogs with otitis externa (5 of which were resistant to enrofloxacin).

Results

Treatment of planktonic cell cultures with blue light resulted in significant (p < 0.5) reductions in Colony Forming Units (CFU) for all seven strains tested, in some cases below the limit of detection. The greatest bactericidal effect was observed following exposure to light at 405 nm wavelength (p < 0.05). Exposure to blue light for 20 min usually resulted in a greater reduction in Pseudomonas aeruginosa than enrofloxacin treatment, and combination treatment typically resulted in the largest reductions in CFU. Analysis of the genome sequences of these strains established that enrofloxacin resistance was likely the result of a S466F substitution in GyrB. However, there was no clear association between genotype and susceptibility to blue light treatment.

Discussion

These results suggest that blue light treatment, particularly at 405 nm wavelength, and especially in combination with enrofloxacin therapy, could be an effective treatment for otherwise recalcitrant canine otitis externa caused by Pseudomonas aeruginosa. It may also provide a way of extending the usefulness of enrofloxacin therapy which would otherwise be ineffective as a sole therapeutic agent.

A Prospective, Blinded, Open-Label Clinical Trial to Assess the Ability of Fluorescent Light Energy to Enhance Wound Healing after Mastectomy in Female Dogs

Mammary gland tumors represent the most frequently diagnosed malignant neoplasm in intact female dogs, and surgical removal represents the current gold standard treatment. To promote wound healing and prevent possible bacterial contamination, perioperative antimicrobials are commonly used in clinical practice, even though there are no publications establishing guidelines for the use of such drugs in canine mastectomy. The aim of the present study was to evaluate the ameliorative effect of fluorescent light energy on the quality of the healing process after mastectomy surgery in female dogs, in the absence of perioperative antimicrobial administration. Nine female dogs received a multiple-gland mastectomy due to gland tumors and received FLE application immediately after surgery and then five days after. The surgical incisions were evaluated by a blind investigator over time using the Modified Hollander Cosmesis and Modified Draize Wound Healing Score systems. Statistical analysis revealed a significant ameliorative effect of FLE in the control of step-off borders, contour irregularities, and excessive distortion. In addition, erythema, edema, and serous discharge were lower for those wounds managed with FLE. These results underscore the advantageous impact of FLE on the healing of post-mastectomy wounds in female dogs, offering the dual benefits of reducing potential infection risks and lessening the home care burden for pet owners.

In vitro evaluation of bactericidal effects of fluorescent light energy on Staphylococcus pseudintermedius and S. aureus

BACKGROUND

Staphylococcus pseudintermedius and S. aureus are bacterial species of importance in veterinary medicine. The increasing incidence of antibiotic resistance necessitates the implementation of novel treatment modalities. Fluorescent light energy (FLE) is used as an adjunctive and primary treatment for canine pyoderma. However, no in vitro studies exist investigating its bactericidal effects against S. pseudintermedius or S. aureus.

OBJECTIVES

To determine the bactericidal effects of FLE on S. pseudintermedius and S. aureus isolates.

MATERIALS AND METHODS

Two meticillin-susceptible S. pseudintermedius (MSSP) isolates, three meticillin-resistant S. pseudintermedius (MRSP) isolates and one meticillin-resistant S. aureus (MRSA) isolate were studied. A commercially available blue light-emitting diode (bLED) lamp and photoconverting hydrogel FLE system was used. All bacteria were exposed to five conditions following inoculation: (i) no treatment (control); (ii) blue light (bLED) once; (iii) bLED twice consecutively; (iv) FLE (bLED and photoconverting hydrogel) once; and (v) FLE (bLED and photoconverting hydrogel) twice consecutively. Each individual exposure was 2 min long.

RESULTS

No statistically significant differences (p < 0.05) were found for any treatment group when each bacterial isolate was evaluated individually, MSSP isolates were grouped, MRSP isolates were grouped, when all S. pseudintermedius isolates were combined, or when all isolates of both Staphylococcus species were combined.

CONCLUSIONS AND CLINICAL RELEVANCE

While clinical success is reported when using FLE to treat Staphylococcus infections in animals, no in vitro antibacterial efficacy was identified for S. pseudintermedius or S. aureus under experimental conditions. The clinical success observed with FLE may be the result of a more complex in vivo response.

Treatment of canine periocular dermatitis with rhytidectomy (surgical face-lift) and fluorescence photobiomodulation: A case report

Canine periocular dermatitis may be associated with excessive facial folds and heavy brows (EFF-HB). There is no gold standard therapy for EFF-HB-associated periocular dermatitis, and conventional medical management may fail. Herein, we describe periocular fluorescence photobiomodulation and rhytidectomy as novel approaches to treat EFF-HB-associated periocular dermatitis refractory to medical management.

Exploring fluorescent light energy as management option for canine superficial bacterial folliculitis

Superficial bacterial folliculitis (SBF) represents a common dermatological diagnosis in dogs that can be successfully managed with either topical and/or systemic treatments. In the present study we evaluated the efficacy of a fluorescent light energy (FLE) device as sole management for SBF. The same FLE device has been shown, as adjunct therapy to systemic antibiotic or alone, to effectively control clinical manifestation of interdigital furunculosis. Twenty dogs were randomized to receive FLE once (six dogs) or twice (six dogs) weekly in comparison with oral anti-biotic (eight dogs) until complete healing. FLE regimen was able to significantly reduce the time needed to clinical resolution for oral antibiotic, supporting owners' compliance and welfare of dogs.

Fluorescent Light Energy in the Management of Multi Drug Resistant Canine Pyoderma: A Prospective Exploratory Study

The increase in prevalence of staphylococcal antimicrobial resistance has been also associated with pyoderma in dogs, and prolonged antibiotic treatment, as often needed in severe cases of pyoderma, has been related to influencing possible development of multidrug resistance (MDR). Fluorescent light energy (FLE) has been indicated to improve pyoderma lesions as adjunct therapy to systemic antibiotics. In the present study, we evaluated the effect of FLE on clinical signs of MDR canine deep pyoderma (CDP) and interdigital furunculosis (CIF) when administered as solely management. Sixteen client-owned dogs affected by CIF (five dogs) and CDP (eleven dogs) were scored using a dedicated scoring system and received a single FLE applications twice weekly, until clinical resolution was achieved. Mean time to achieve complete resolution was 5.20 ± 3.56 weeks (median 3 weeks) for CIF cases and 4.18 ± 1.47 weeks (median 4 weeks) for CDP ones. FLE shows promise as an aid to managing clinical signs while reducing reliance on antibiotics for MDR CDP and CIF. In this study, FLE was responsible for the decrease in lesion scores and resolution of MDR pyoderma infection without any adjunct therapy, having a potential useful role to play in antibiotic stewardship programs, efficiently promoting complete clinical resolution of MDR lesions while optimizing the use of antibiotics.

Critically Appraised Topic on Low-Level Laser Therapy (LLLT) in Dogs: An Advisable Treatment for Skin Diseases?

Simple Summary

Low-level laser therapy (LLLT) is a therapeutic technique with reported regenerative, anti-inflammatory, antibacterial, and analgesic effects. In the last few years, LLLT has been used in dogs for the management of different skin lesions and diseases. This study reports a literature review using the critically appraised topic (CAT) method to determine the canine skin diseases for which LLLT is an advisable treatment. Only primary clinical prospective studies were considered. A meticulous literature search revealed 19 significant clinical trials, and these were critically analyzed. The evaluation of the best accessible evidence in July 2022 suggests that LLLT can be a promising and effective adjunctive treatment in combination with systemic antibiotic therapy for canine interdigital pyoderma and canine deep pyoderma. Furthermore, the use of LLLT is not recommended as a therapy for pedal pruritus secondary to canine atopic dermatitis. In other canine skin diseases, there is a possible helpful effect of LLLT; however, the evidence for its use is not currently convincing.

Abstract

Low-level laser therapy (LLLT) is a therapeutic option that stimulates cellular function through intracellular photobiological and photochemical reactions, promoting better tissue repair and an anti-inflammatory, antibacterial, and analgesic effect. Previous studies in human and veterinary medicine have shown the clinical efficacy of LLLT in many fields. In this study, the literature was reviewed using the critically appraised topic (CAT) method to determine the canine skin diseases for which LLLT is an advisable treatment. A meticulous literature search revealed 19 significant clinical trials, which were critically analyzed. The evaluation of the best accessible evidence in July 2022 suggests that fluorescence biomodulation (FBM), a type of LLLT, can, in combination with systemic antibiotic therapy, be a promising and effective adjunctive treatment for canine interdigital pyoderma and canine deep pyoderma. Furthermore, the evidence suggests that the use of LLLT is not recommended as a therapy for pedal pruritus secondary to canine atopic dermatitis. For other canine skin diseases included in the CAT, although LLLT appears to be a promising treatment, there is not yet good scientific evidence to recommend its use.

Fluorescence Biomodulation for Canine Interdigital Furunculosis: Updates for Once-Weekly Schedule

Interdigital furunculosis is a common multifactorial, inflammatory disease of the canine interdigital skin in which lesions commonly become secondarily infected. Fluorescence biomodulation (FBM) administered twice weekly has shown to effectively control clinical manifestation as adjunct therapy to systemic antibiotic. Since twice weekly regimen could be unaffordable for some pet owners, the aim of this study was to evaluate the effect of once weekly application of FBM in combination with systemic antibiotic on clinical manifestations of canine interdigital pyoderma, comparing the results to those present in literature. Twelve dogs diagnosed with interdigital pyoderma received antibiotic plus once weekly FBM application. Dogs were scored until complete healing based on global lesion score and neutrophil engulfing bacterial score. The results obtained demonstrated that once weekly application of FBM exerts the same beneficial effect on interdigital furunculosis healing as per twice weekly, indicating that once weekly regimen is well tolerated and is yielding similar results to twice weekly applications.