Underwater treadmills are more suited to muscle development and is more commonly used where a dog has had cruciate or hip displasia ops as well as shaping for show dogs and building/ developing muscles in greyhounds and such.
Straight swimming is better for overall fitness and weight control.
I think your dog is training you to stop after 5 minutes of jogging and, unless there is an underlying medical issue, I would extend time and distance. What does she do to tell you she has done enough?
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