Canine hydrotherapy is a form of hydrotherapy directed at the treatment of chronic conditions, post-operative recovery, and pre-operative or general fitness in dogs. Wikipedia
As an alternative or complement to weight-bearing exercise and medication, canine hydrotherapy may speed recovery after operations or slow the progression of degenerative conditions. It may be used as a pre-operative fitness regime to allow a dog to maintain condition before an operation if it can not exercise normally. When a congenital condition is identified in a puppy, it may be the case that surgery is not possible until the animal is physically mature; during the period preceding the surgery, hydrotherapy can be employed to maintain the dog’s condition.
Spinal injuries or surgery can cause impairment of motor function, which may be treated by allowing the dog to exercise in water; it provides support and allows the dog to exercise its muscles while nerve regeneration is taking place. Degenerative conditions can make normal weight bearing exercise difficult and pressure on joints and limbs may aggravate some conditions, so hydrotherapy can be used in these cases to allow the dog to exercise in an environment where there is no pressure on the affected areas.
Obese dogs can build fitness and lose weight as a result of exercise in a hydrotherapy pool without putting excessive weight on their joints. Hydrotherapy may be used as part of a general fitness routine for dogs. Wikipedia