You could use just about anything. I use PVC pipe that I have around we started out walking and then trotting over them. I do it while on his back and on the ground. I also vary the distances and height so that way they have to pay attention to what they are doing. I also have an area the I can walk over and step up and down telephone poles. Also maybe ask you farrier to square or roll the toe to help with breakover. Depending on age it could be early arthritis setting in.

Hope this helps