Underground and overground water treadmills can be useful tools when rehabilitating horses after a variety of injuries or conditioning them for sport. Swimming can also be used for rehabilitation but is more suited toward conditioning due to its more strenuous nature. The modality used depends on the goal—rehab or conditioning—said Steve Adair, MS, DVM, Dipl. ACVS, ACVSMR, a professor at the University of Tennessee, in Knoxville, in his presentation at the inaugural American College of Veterinary Sports Medicine and Rehabilitation Symposium, held April 27-30 in Charleston, South Carolina.

How Water Treadmills Help Horses Heal

Aqua therapy’s most important mechanisms of action are buoyancy, which can range from the horse being totally weight-bearing to almost non-weight-bearing, and resistance, which increases the animal’s sensory awareness and workload. The greater the resistance, the greater strengthening the exercise provides, said Adair. The secondary mechanisms of action with aqua therapy are joint motion, hydrostatic pressure, and thermal effects.

“The primary use for underground and overground water treadmills in rehabilitation is to provide therapeutic exercise to the horse in a reduced weight-bearing environment with controlled stress on the injured tissue,” he explained, describing below- and aboveground units (underground units hold more water, creating more buoyancy; aboveground allow you to tailor the water depth to the rehab protocol). Owners and veterinarians can also use all three modalities for full body and cardiovascular conditioning of “normal” horses to improve or maintain performance.

When rehabilitating a horse in an underground or overground water treadmill, buoyancy allows the horse to exercise without further trauma to the injured tissue and can be adjusted based on the water level: The higher the water level, the greater the buoyancy. Hydro-jets aerate the water and can be used to increase buoyancy and resistance. Higher water levels and speed also create greater resistance than lower speeds and water levels, added Adair, resulting in an increased workload.

“The height of the water affects joint motion,” said Adair. “Slightly higher water will increase joint flexion, but once the water is above the carpal (knee) area, the joint flexion plateaus. This is the same in both the front and hind limbs.”

Safety Considerations When Using Aqua Therapy With Horses

Handlers must consider safety in any water activity with horses, whether for conditioning or rehabilitation. In either type of underwater treadmills horses might panic and try to jump or climb out, but these machines have emergency exits, Adair said. “Reconditioning muscles, the cardiovascular system, or mental status of the horse prior to full skeletal recovery might lead to an overeager horse that reinjures itself,” he noted.

When considering swimming as a conditioning tool, it is important veterinarians and owners understand that horses are not natural swimmers. Horses have unnatural locomotion when swimming, with their head high, back extended, no contact with the ground, and violent kicking of the back legs, said Adair. “I just find that it is too violent for rehabilitation and recommend that it only be done for conditioning.”

The water pressure on the chest of the horse when swimming can cause respiratory stress in some horses, and most pools don’t have emergency exits.

Water Treadmill Choice for Horses Depends on Your Goals

“For conditioning horses, I recommend utilizing swimming, an overground treadmill with an incline, or an underground treadmill,” said Adair. “When rehabilitation is the goal, I use an underground or overground treadmill and adjust the height of the water based on the individual horse’s needs. I start by having them walk slow in higher water for 15-20 minutes, three to five days per week, and gradually build up to 40-45-minute sessions over a two- to four-week period.”