Penetration Profiles of a Class IV Therapeutic Laser and a Photobiomodulation Therapy Device in Equine Skin.
Authors: Luna Stelio Pacca Loureiro, Schoen Allen, Trindade Pedro Henrique Esteves, Rocha Paula Barreto da
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Light Penetration Profiles in Equine Photobiomodulation Therapy Whilst photobiomodulation therapy (PBMT) is increasingly used in equine practice, the actual tissue penetration of different devices remains poorly characterised—a critical gap given that therapeutic efficacy depends entirely on light reaching target tissues. Loureiro and colleagues compared penetration profiles of a Class IV therapeutic laser against a portable PBMT device in 12 clinically healthy horses (six with light coat, six with dark coat), measuring skin thickness via ultrasound and quantifying light transmission through the skin using an optical power meter over 120 seconds post-application. The PBMT device demonstrated substantially greater energy penetration than the Class IV laser across both coat colours (0.01303 versus 0.00122, *P* < 0.001), with skin pigmentation also influencing penetration efficiency of the PBMT system. These findings suggest that portable PBMT devices may deliver superior therapeutic dosing to deeper tissues than traditional Class IV lasers in clinical applications, and that practitioners should account for coat colour when estimating effective tissue penetration. For farriers and therapists incorporating light therapy into treatment protocols, this work reinforces that device selection and patient coat colour warrant careful consideration when targeting specific tissue depths, particularly for conditions affecting deeper structures such as suspensory ligaments or deep flexor tendons.
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Practical Takeaways
- •If selecting between these two devices for therapeutic laser treatment, PBMT devices deliver significantly better penetration depth than class IV lasers in equine skin
- •Account for coat color when using PBMT—darker skin may respond differently to treatment than lighter skin due to altered penetration profiles
- •Ultrasonography can reliably measure skin thickness as an alternative to cutometry for baseline assessment before treatment
Key Findings
- •PBMT device penetrated skin significantly deeper (0.01303 ± 0.00778) compared to class IV laser (0.00122 ± 0.00070) with P < 0.001
- •Light penetration was greater in both light and dark skin regions with PBMT versus class IV laser
- •Skin color (light vs dark) changes penetration profiles of PBMT therapy
- •No significant difference in skin fold width measurements between cutometer and ultrasonography methods