Veterinarians might soon turn to a new, high-tech treatment option for horses with gait-altering fibrotic myopathy: laser surgery.

When a horse suffers a skeletal muscle injury the normal healing process results in scar tissue formation at the injury site. Scar tissue is relatively inelastic and, depending on how much forms and where it develops, it can compromise motion by reducing the affected muscle’s elasticity. In horses, this movement restriction in hamstring muscles is called fibrotic myopathy. Typically, only one hind limb is affected, but both limbs can be affected—in which case one side is more severely affected than the other. While this condition has long been diagnosed, veterinarians still don’t fully understand its impact on locomotion, and current treatment options aren’t always effective.

To that end, researchers at the University of Missouri (UM) carried out a multifaceted study to evaluate fibrotic myopathy’s effects on equine locomotion and laser surgery’s ability to cut through scar tissue in hamstring muscles. The team also examined whether a rapid return to exercise encourages affected horses’ tissues to remain more elastic.

“Exercise soon after surgery helps to stretch the immature scar tissue, leading to longer (i.e., less restrictive) mature fibrotic tissue, which will not produce significant effects on the forward advancement of the leg,” said study co-author Marco Lopes, MV, MS, PhD, research associate at the MU College of Veterinary Medicine.

Lopes and colleagues performed gait analysis with high-speed cameras on eight horses with fibrotic myopathy before the