Effectiveness of photo-ozone therapy against equine Pythium insidiosum.
Authors: Rodrigues V S, Trevisan L A C, Cintra B S, Pires R H, Ribeiro A B, Tavares D C, Oberhaus E, Ferreira J C
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Photo-ozone therapy against equine Pythium insidiosum Cutaneous pythiosis represents a significant clinical challenge in equine practice, often requiring aggressive intervention to prevent progression and tissue loss. Researchers isolated Pythium insidiosum from ten affected horses and tested the antimicrobial efficacy of combined photo-ozone therapy (low-level laser therapy [LLLT] plus ozone) against cultured hyphae samples across four treatment groups (n=30 plugs each), monitoring growth inhibition over 21 days and assessing cytotoxic effects on equine keratinocytes. The combination therapy proved substantially more effective than either modality alone, inactivating 92.3% of fungal samples compared to only 30% with ozone monotherapy, whilst LLLT monotherapy failed entirely with 100% hyphae persistence; critically, no regrowth occurred when inactivated plugs were recultured on fresh media, suggesting genuine pathogen destruction rather than temporary growth suppression. Although the sequential LLLT-O3 protocol demonstrated a modest 20% cytotoxic effect on skin cells in vitro, this remained clinically acceptable compared to the dramatic antimicrobial activity observed. For practitioners managing pythiosis cases, these findings suggest that combined photo-ozone therapy warrants investigation as a potential adjunctive or primary treatment modality, though further in vivo studies and clinical validation will be essential before widespread protocol adoption.
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Practical Takeaways
- •Photo-ozone therapy may offer a promising adjunctive treatment for cutaneous pythiosis in horses, achieving high pathogen inactivation rates in vitro with minimal harm to healthy tissue
- •Combination therapy (LLLT + ozone) was significantly more effective than either treatment alone, suggesting synergistic antimicrobial action worth investigating clinically
- •While in vitro results are encouraging, clinical efficacy and optimal treatment protocols in live equine pythiosis cases remain to be validated through field trials
Key Findings
- •Photo-ozone therapy (LLLT-O3) inactivated 92.3% of P. insidiosum hyphal samples compared to 30% with ozone alone and 0% with LLLT alone
- •Inactivated hyphal plugs showed no regrowth after 7-day reculture on fresh media, indicating viable pathogen elimination
- •LLLT-O3 treatment caused only 20% cytotoxicity in HaCaT keratinocytes versus isolated treatments which showed negligible toxicity
- •Combined photo-ozone therapy demonstrates superior antimicrobial efficacy against equine P. insidiosum with acceptable safety margin for skin cells