Although subtle in its onset, osteoarthritis (OA) is one of the most common and career-ending musculoskeletal injuries in horses. Results from a 1998 study revealed that U.S. horse owners spent more than $700 million on medical and surgical management of horses with OA that year.
Recently, Melissa King, DVM, PhD, Dipl. ACVSMR, assistant professor in Equine Sports Medicine and Rehabilitation at Colorado State University's Veterinary Teaching Hospital, in Fort Collins, conducted a study to determine whether aquatic exercise could help reduce OA's detrimental effects. She presented her results at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.
As OA progresses, affected horses often adapt to discomfort by changing their gaits and/or stance. But this frequently does more harm than good. "What are protective actions become maladaptive," she said.
While there's limited data on aquatic exercise's effects on horses, in humans this therapy helps increase limb strength, joint mobility, muscle activation, and neuromotor control. King explained that water's buoyancy helps reduce loading on joints or injured limbs, its hydrostatic pressure reduces edema (fluid swelling), and its high viscosity (which is 12 times that of air) means horses must exert increased effort to move.
To determine whether aquatic exercise could help improve OA-affected horses' balance and postural control—and, thus, help slow the disease's progression—King induced OA in 16 horses' middle carpal (knee) joints. Half of the horses exercised five days a week on an underwater treadmill (with water at shoulder height, which reduces 50-60% of body weight) for 70 days, and the other half served as controls, exercising on a normal high-speed treadmill at the same speed and duration as the underwater treadmill group. The researchers collected force plate data (e.g., movements and center of pressure) from each horse while it stood in three different stance conditions (normal/square, base narrow, and blindfolded) at Days 0, 14, 42, and 70.