High-Power Laser Therapy Improves Healing of the Equine Suspensory Branch in a Standardized Lesion Model

Histological tissue healing following high-power laser treatment in a model of suspensory ligament branch injury

BACKGROUND

High-power laser therapy gained popularity recently as a regenerative treatment for tendinitis and desmitis in the horse. However, studies evaluating effects of laser therapy on tissue repair at histological level in large mammals are lacking.

OBJECTIVES

To evaluate effects of high-power laser therapy on suspensory desmitis healing, using a model of suspensory ligament branch injury.

STUDY DESIGN

In vivo experiments.

METHODS

Standardised lesions were surgically induced in all 4 lateral suspensory branches of twelve healthy Warmblood horses. Laser therapy (class 4, 15W) was applied daily on 2 of 4 induced lesions for 4 consecutive weeks. Horses were randomly assigned to either short-term study (horses were sacrificed after 4 weeks) or long-term study (6 months). Suspensory ligament samples were scored after staining with haematoxylin-eosin and immunostaining for collagen 1- collagen 3- and factor VIII.

RESULTS

In the short-term study, significantly better (lower) scores for variation in density (17% above cut-off score in treated lesions vs. 31% above cut-off score in controls, p=0.03), shape of nuclei (54% vs. 92%, p=0.02), fibre alignment (32% vs. 75%, p=0.003) and fibre structure (38% vs. 71%, p=0.02) were found in laser treated lesions when compared to controls. Collagen 3 expression was significantly higher (32% vs. 19%, p=0.006) in control lesions. In both short- and long-term studies combined, parameters lesion size (44% vs. 56%, p=0.02) and shape of nuclei (53% vs. 84%, p=0.05) scored significantly better in treated lesions. Long-term, significantly better (lower) scores were found in the laser-treated group for lesion size (15% vs. 45%, p=0.008) and a higher percentage above cut-off score for density of the nuclei (27% vs. 9%, p=0.02), compared to controls.

MAIN LIMITATIONS

The model of suspensory branch injury is not an exact representation of clinical overstrain lesions.

CONCLUSIONS

These results suggest that high-power laser therapy enables better lesion healing than conservative treatment.