During inflammation, the hydrostatic pressure applied by water on a submerged body part promotes lymphatic drainage and circulation, which consequently removes inflammatory toxins, provides pain relief and reduces oedema. In water the pain associated with weight-bearing is minimised, enabling early-onset exercise while minimising the risk of falls, erratic movements and secondary soft tissue damage. Water viscosity provides more resistance to movement than air, thus promoting strengthening, endurance and straightness while exercising at a slower pace. Greater joint flexion is achieved during water exercise compared to land exercise, particularly when a joint is submerged just below the water’s surface.
The moving belt of a hydrotherapy treadmill passively extends the joints of the limb and the ground contact experienced in a hydrotherapy treadmill simulates an on-land gait-pattern, incurring the stresses required for return to full function. Alternatively, swimming is a completely non-weight bearing form of exercise and is therefore ideal for recumbent patients. Additionally, the increased muscular and cardiovascular effort required by swimming makes it also ideal for fitness training. A combination of land and water exercise is recommended for returning animals to full function.
In horses exercise in water also promotes core muscle strengthening and encourages the horse to work in a round outline.
Post-operatively, hydrotherapy must only be implemented once the surgical wound has sealed and the stitches have been removed, unless otherwise advised by your veterinarian. Hydrotherapy must only be performed in a safe and controlled environment and cold water is contraindicated in osteoarthritic dogs, instead warm water (~30C) is preferable. On the other hand, horses must be exercised in water no warmer than air temperature due to their sensitivity to over-heating.