Why Underwater Treadmill Depth Matters for Joint Loading in Dogs Water depth dramatically changes how much weight and force a dog places through their joints during underwater treadmill therapy. By adjusting the water level, we can carefully control joint loading, muscle activation, balance demands and gait mechanics — making hydrotherapy highly adaptable for both rehabilitation and conditioning. How Water Reduces Joint Loading Water creates buoyancy, which supports part of the dog’s body weight. The deeper the water, the more buoyancy provided and the less load placed through the limbs and joints. This means: * Higher water levels = less weight bearing * Lower water levels = more weight bearing For dogs with pain, arthritis, post-operative restrictions or weakness, this reduction in loading allows movement with less discomfort and reduced stress on healing tissues. Approximate Effects of Water Depth Hip Height Water * Greatest buoyancy support * Significant reduction in joint compression * Easier for painful or weak dogs to move * Encourages range of motion and early gait retraining * Often used post surgery or with neurological patients Stifle (Knee) Height Water *Moderate unloading *Increased muscle engagement compared to deeper water * Useful during mid-stage rehabilitation * Encourages controlled strengthening while still protecting joints Hock Height Water * Minimal unloading * Higher limb loading and greater strengthening demand * More challenging for balance and stability * Often used for conditioning and return-to-function work Why This Is Important Changing water depth allows therapists to progressively increase or decrease difficulty without increasing concussive forces seen on land. For example: * A painful arthritic dog may initially work in deeper water to improve mobility comfortably. * A post-TPLO patient may gradually transition to shallower water as healing progresses and stronger weight bearing is required. * A sporting or show dog may train in lower water to improve strength, drive and endurance. Water Depth Also Changes Gait Mechanics Different depths influence: * Stride length * Joint flexion and extension * Muscle recruitment * Core activation * Balance and proprioception Deeper water often slows movement and increases flexion, while shallower water encourages more natural loading patterns and propulsion. The Key Takeaway Underwater treadmill therapy is far more than “walking in water.” Precise depth adjustments allow rehabilitation professionals to tailor joint loading and exercise intensity to each individual dog’s needs, stage of recovery and conditioning goals.