A Preliminary Study of the Influence of High Intensity Laser Therapy (HILT) on Skin Surface Temperature and Longissimus Dorsi Muscle Tone Changes in Thoroughbred Racehorses with Back Pain

SIMPLE SUMMARY: Back pain in Thoroughbred racehorses is frequent and significantly decreases their athletic performance. The most common thoracolumbar alteration in Thoroughbreds is Kissing Spines Syndrome (KSS). The objective of the current study was to evaluate and compare soft tissue response to high-intensity laser therapy (HILT) by measuring changes in skin surface temperature and longissimus dorsi muscle tone, located in the thoracolumbar back area, in Thoroughbreds with back pain diagnosed with and without KSS. The Thoroughbreds were divided into two groups, those with KSS (n = 10) and those without KSS (n = 10). A single laser treatment of the longissimus dorsi muscle (on the left side, between the fifteenth thoracic and the second lumbar vertebrae) was performed. Thermographic examination and palpation were repeated before and after HILT to assess changes in skin surface temperature, muscle tone and pain response. In both groups, HILT was associated with an average skin surface temperature increase of 2.5 °C and a palpation score reduction of 1.5 points, without any differences between the groups. In conclusion, HILT was found to be a safe and supportive treatment method for longissimus dorsi muscle pain and discomfort as assessed by digital palpation in Thoroughbreds. The results of the present study are encouraging, but further studies with larger samples, a longer follow-up period and comparisons with placebo control groups are needed to draw a more valid conclusion. ABSTRACT: The reason for undertaking this study was to investigate soft tissue response to high-intensity laser therapy (HILT) by measuring changes in skin surface temperature and longissimus dorsi muscle tone in the thoracolumbar back area in Thoroughbreds with back pain and diagnosed with and without Kissing Spines Syndrome (KSS). Thoroughbreds aged 3–4 years with clinically presented back pain underwent a radiological examination (to assess a lack or presence of KSS) and longissimus dorsi muscle palpation (to assess muscle tone and pain degree). The subjects were divided into two groups, those with KSS (n = 10) and those without KSS (n = 10). A single HILT treatment on the longissimus dorsi muscle, on the left side, was performed. Thermographic examination and palpation were repeated before and after HILT to assess changes in skin surface temperature and muscle pain response. In both groups, HILT caused a significant increase in skin surface temperature of 2.5 °C on average and a palpation score reduction of 1.5 degrees on average (p = 0.005 for both measurements), without differences in any outcome measures between the groups. Furthermore, the correlation between changes in the average skin surface temperature and the average palpation scores in horses with and without KSS were negative (rho = 0.071 and r = −0.180, respectively; p > 0.05). The results of the present study are encouraging, but further studies with larger samples, a longer follow-up period and comparisons with placebo control groups are needed to draw a more valid conclusion.