He-Ne laser therapy by fibroendoscopy in the mucosa of the equine upper airway

Abstract
Background and Objective: A study was made of the effects of low‐level laser irradiation on the cicatrization of superficial wounds in the pharyngeal mucosa of the horse. Study Design/Materials and Methods: Duplicate pharyngeal mucosal ulcers were induced in 12 Spanish horses with submucosal injection of sulfuric acid. A fibroendoscope and an He‐Ne laser were used to treat one of the ulcers and the second ulcer in each animal was left untreated, serving as a control. Biopsy samples for the histological study were taken after the seventh laser therapy session from the two animals. Results: Irradiated lesions cicatrized at 10.5 days and nonirradiated lesions cicatrized at 18.0 days. Statistical analysis revealed highly significant differences (P < 0.0001) between the irradiated and control groups. Histological study of the control samples showed epithelial coagulation necrosis, edema, and microthrombi. However, in samples from the irradiated lesions no inflamatory edema, numerous active fibroblasts, connective tissue, and intensive epithelial regeneration were observed. Conclusion: Macroscopic and microscopic results indicated that laser treatment accelerated the cicatrization. Irradiated lesions cicatrized faster than control. These results suggest beneficial effects of low‐level laser irradiation therapy on equine pharyngeal ulcerative lesions.