Yes, it's just a normal physio ball. I got a heavy duty one. For exercises in which the dog is standing on the ball with two feet or doing other weight bearing, you want a ball that is as close to the height of his shoulders, but not over the height, as possible. This should also work for most other things, such as learning treiball basics, though I don't know much about treiball. (We did some pushing and rolling, because it's great exercise.) You can adjust ball height just a bit by adding or letting out air. There are a lot of videos on Youtube about treiball. It's like herding sheep, except you use the balls. It's a very new sport. Since most of use don't have very good access to sheep, treiball is generally more convenient.