Rehabilitation of human patients after injury is common and it is becoming more common in equine medicine. One of the most common forms of rehabilitation in horses is hydrotherapy. Cold water hydrotherapy cools the tissues, decreasing pain by reducing conduction velocity of peripheral nerves. Also, cooling decreases the metabolism of the tissues reducing requirements for oxygen and glucose. Cooling also causes constriction of blood vessels which decreases bleeding and inflammation. For this kind of cold water benefit, spraying cold water on the leg is not enough. Ice is required because tissue temperatures need to get down to 10°C to reach the tissues.
Alternating therapy of cold and heat can also be helpful for treating soft tissue injuries by increasing blood flow to tissues. Cold constricts the blood vessels, while heat dilates them, increasing blood flow. However, it is very difficult to consistently heat the tissue to 40°C and then cool it to 15°C. A cold water leg spa that sprays the leg with cold salt water and air to help decrease swelling and increase oxygen to the tissue has been used but there are no studies to support this use.
Underwater treadmills are commonly used for horses and have been shown to be effective for improved limb function and range of motion. The underwater treadmill is also helpful for some cardio work and is better than swimming for targeting specific joints. Although swimming is great exercise, it should not be used for injured horses or horses with respiratory dysfunction as swimming horses hold their breath after inspiration.