This study investigates the susceptibility of common pathogens to totarol and assesses its clinical effectiveness in promoting wound healing in client-owned dogs with open wounds. Twenty-three client-owned dogs with open wounds were divided into two groups: (1) the treatment group (T-group) and (2) the control group (C-group). Clinical samples were collected from the wounds for the bacterial identification and determination of the minimum inhibitory concentrations (MICs) of totarol. In the T-group, wounds were treated with standard wound care together with the application at a dosage of 0.3 mL (two sprays) of commercial totarol product per 25 cm² of the wound area. The C-group received only standard wound care. This in vitro study found that totarol exhibited antimicrobial activity against both standard pathogens and clinical wound pathogens. The MIC values of totarol dissolved in absolute ethyl alcohol were 4 µg/mL for Gram-positive pathogens and ranged from 256 to 512 µg/mL for Gram-negative pathogens. However, the MIC values of the commercial totarol product ranged from 512 to 1024 for both Gram-positive and Gram-negative pathogens. Clinically, the use of a commercial totarol product as an adjunctive therapy significantly improved wound healing, as indicated by a greater percentage of wound area reduction (p < 0.05). From day 2 to day 7 of the treatment, the percentage of wound area reduction differed significantly between the T-group and the C-group. At the end of the study, the average percentage of wound area reduction was 69.18% ± 18.12 and 41.50% ± 20.23 in the T-group and C-group, respectively. The finding of this study illustrates the antimicrobial properties of totarol and its product against prevalent wound pathogens. These results suggest the potential of totarol as an adjunctive option for canine wound care.

Background and Aim: Antibiotic resistance poses a growing threat to wound management in veterinary medicine. Blue light phototherapy has emerged as a non-antibiotic bactericidal alternative with additional benefits for wound healing. However, its effectiveness in clinical veterinary contexts remains inadequately explored. This study evaluated the bactericidal efficacy of 465-nm blue light against standard pathogens and bacteria isolated from infected canine wounds, aiming to determine optimal energy doses for clinical use. Materials and Methods: Three standard bacterial strains – Staphylococcus aureus (American Type Culture Collection [ATCC] 25923), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922) – along with five clinical isolates from canine wounds, were exposed to 465-nm blue light at energy doses of 28, 56, and 112 J/cm2 (15, 30, and 60 min, respectively). Colony-forming units (CFUs) were quantified post-irradiation and compared to non-irradiated controls. Statistical significance was assessed using appropriate parametric and non-parametric tests. Results: P. aeruginosa (ATCC 27853) exhibited significant, dose-dependent inhibition at all energy doses, resulting in reductions of 36.3%, 60.5%, and 82.8%. Clinical P. aeruginosa isolates demonstrated 21.1% and 78.8% inhibition at 56 and 112 J/cm2, respectively (p < 0.05). E. coli (ATCC 25922) was significantly inhibited only at 112 J/cm2 (46.4% reduction, p = 0.045). No significant reductions were observed for S. aureus, Acinetobacter baumannii, Staphylococcus haemolyticus, clinical E. coli, or Enterococcus faecalis at any dose. Conclusion: Blue light at 465-nm exhibits selective bactericidal activity, effectively inhibiting P. aeruginosa and E. coli (ATCC), with efficacy dependent on bacterial species and applied energy dose. Its limited effect on other pathogens underscores the importance of species-specific treatment planning. Higher energy doses (112 J/cm2) may be required in unknown or mixed infections. Further investigation is recommended to refine device specifications and assess clinical utility in veterinary settings. Keywords: antimicrobial resistance, blue light therapy, Escherichia coli, photoinactivation, Pseudomonas aeruginosa, veterinary phototherapy.