My brother-in-law, Dr. Jeff Bowra, is a veterinarian and he has an animal hospital in Aldergrove, here in BC. What's cool is that his clinic was the first clinic in all of Canada to have a pool and hydro-treadmill and is the first of its kind in all of the world.
The stainless steel 12' x 6' salt water (no disinfectant chemicals needed) pool has a treadmill that is adjustable depending on a dog's height. There are four jets which create currents for dogs to swim against and the entire room has a specialized dehumidification system to keep the room's humidity and temperature down while keeping the pool warm.
There's an underwater camera system in place to record the dog's recovery progress / gait as it walks and/or swims.
There's a harness system hooked up to an electric winch system to help lift some of the patients up and lower them into the pool. It's pretty impressive.