Intravenous Injection of Sodium Hyaluronate Diminishes Muscle Inflammation

I was not aware of the practice of using hyaluronate IV for horses in competition. In this study, the practice is evaluated for efficacy and to look at the possible adverse effects of using antiinflammatories on muscle recovery following exercise. The practice was effective at reducing inflammation and did not appear to interfere with post-exercise muscle recovery. The paper does go on to say that the process is a complicated one and further study is needed. It should be noted this is off-label use and you should discuss this thoroughly with your veterinarian before such use.
DrO

Excerpted from the article’s discussion:
“The systemic delivery of HA prior to competitions is gaining popularity in the lay equestrian community, possibly due to its nociceptive properties [26]. Because of its noted anti-inflammatory properties, the hypothesis that HA injection would suppress inflammatory gene expression in skeletal muscle and impede the immediate post-exercise recovery period was tested in adult horses.”

Intravenous Injection of Sodium Hyaluronate Diminishes Basal Inflammatory Gene Expression in Equine Skeletal Muscle
Animals (Basel). 2023 Sep 27;13(19):3030. doi: 10.3390/ani13193030.
Authors
Savannah R Gregg 1 , Madison R Barshick 1 , Sally E Johnson 1
Affiliation

1 School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA.

PMID: 37835636
DOI: 10.3390/ani13193030

Abstract

Following strenuous exercise, skeletal muscle experiences an acute inflammatory state that initiates the repair process. Systemic hyaluronic acid (HA) is injected to horses routinely as a joint anti-inflammatory. To gain insight into the effects of HA on skeletal muscle, adult Thoroughbred geldings (n = 6) were injected with a commercial HA product weekly for 3 weeks prior to performing a submaximal exercise test. Gluteal muscle (GM) biopsies were obtained before and 1 h after exercise for gene expression analysis and HA localization. The results from RNA sequencing demonstrate differences in gene expression between non-injected controls (CON; n = 6) and HA horses. Prior to exercise, HA horses contained fewer (p < 0.05) transcripts associated with leukocyte activity and cytokine production than CON. The performance of exercise resulted in the upregulation (p < 0.05) of several cytokine genes and their signaling intermediates, indicating that HA does not suppress the normal inflammatory response to exercise. The transcript abundance for marker genes of neutrophils (NCF2) and macrophages (CD163) was greater (p < 0.05) post-exercise and was unaffected by HA injection. The anti-inflammatory effects of HA on muscle are indirect as no differences (p > 0.05) in the relative amount of the macromolecule was observed between the CON and HA fiber extracellular matrix (ECM). However, exercise tended (p = 0.10) to cause an increase in ECM size suggestive of muscle damage and remodeling. The finding was supported by the increased (p < 0.05) expression of CTGF, TGFβ1, MMP9, TIMP4 and Col4A1. Collectively, the results validate HA as an anti-inflammatory aid that does not disrupt the normal post-exercise muscle repair process. Keywords: equine; exercise; hyaluronic acid; inflammation; skeletal muscle.

Excerpted from the article’s conclusion:
“Sodium hyaluronate acts as an anti-inflammatory in equine skeletal muscle through the suppression of basal inflammatory gene expression. Genes involved in leukocyte activation and cytokine production are not irreversibly downregulated and exhibit increased expression following an exercise stressor. Expression analysis pre- and post-exercise reveals a complex cellular network replete with monocytes, macrophages, fibroblasts and myogenic precursors. The interactions between these cells following exercise and during metabolic insults and disease require further elucidation.”