I made some ice boots years ago and they worked very well. You do have to use bagged ice though. I took a couple pair of old jeans and cut the legs off. Put one inside the other so you have a double layer. Sew the bottom together of both layers so it will hold the ice but leave the top open so you have a sort of a bag. Attach velcro to the top, and the bottom so you can velcro attach on the horses leg. Slip the boot on and pull up the leg and secure the bottom velcrow around the pastern. Fill between the 2 layers with ice, and secure the top velcro. It worked well for years and ice is available where ever you go.