Comparison of the Effect of High-Intensity Laser Therapy (HILT) on Skin Surface Temperature and Vein Diameter in Pigmented and Non-Pigmented Skin in Healthy Racehorses.
Authors: Zielińska Paulina, Soroko Maria, Howell Kevin, Godlewska Maria, Hildebrand Weronika, Dudek Krzysztof
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: High-Intensity Laser Therapy Response in Pigmented versus Non-Pigmented Equine Skin Melanin content fundamentally alters how equine tissue responds to high-intensity laser therapy (HILT), according to research conducted on 20 Thoroughbreds comparing treatment effects on pigmented and non-pigmented skin over the lateral fetlock joint. Using thermographic and ultrasonographic imaging immediately before and after HILT application, researchers documented a striking divergence in thermoregulatory response: pigmented skin experienced significant temperature elevation whilst non-pigmented skin temperatures actually decreased (p < 0.001), indicating that melanin actively absorbs and converts laser energy into heat rather than allowing it to penetrate deeper. Despite these contrasting surface temperature changes, lateral digital palmar vein diameter increased in both groups following treatment, though the difference between groups was not statistically significant (p = 0.14), suggesting that vascular effects may operate through mechanisms partially independent of superficial heat generation. For practitioners selecting HILT as a therapeutic modality, these findings underscore the importance of skin pigmentation as a treatment variable—pigmented areas will generate greater local heat accumulation, which may benefit some conditions whilst potentially limiting deeper tissue penetration, whereas non-pigmented areas may allow greater photon penetration despite less dramatic surface heating. Further investigation into the clinical significance of these photothermal differences is warranted, particularly regarding optimal treatment protocols for varied equine phenotypes and specific soft tissue pathologies.
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Practical Takeaways
- •Skin pigmentation significantly affects thermal response to HILT treatment, with pigmented skin showing increased temperature while non-pigmented skin shows decreased temperature—practitioners should account for this variable when treating horses with different coat colours
- •Vascular effects (increased vein diameter) occur similarly regardless of skin pigmentation, suggesting HILT may improve local circulation independent of melanin content
- •Further research is needed before making definitive clinical recommendations, but these findings suggest HILT's photothermal effects depend on tissue melanin concentration
Key Findings
- •Pigmented skin surface temperature increased significantly after HILT while non-pigmented skin temperature decreased (p < 0.001)
- •Vein diameter increased after HILT in both pigmented and non-pigmented skin groups with no significant difference between groups (p = 0.14)
- •Melanin content in the epidermis plays an important role in light energy absorption and photothermal effects of HILT
- •Vein diameter changes suggest that photothermal mechanisms in irradiated tissue may partly explain vascular responses to HILT