Broken horn repairs must be done as soon as possible after the break. Most horns break and go down rather than up, therefore the repair must normally lift the horn back up to a normal symmetrical shape. Often the horn will not go back into the exact original place. It will not easily squeeze into the jagged edges and will need pressure.
For repairs you will need 3 items: a half dozen rolls of cast material, one ladies underwear (new or used but clean) and a rebar rod a little shorter than the total horn spread.
Place the broken horned critter carefully in a squeeze chute. Promptly attach a nose tong and tie its' head in a direction so it can not flop around and do more damage to the broken horn.
It will heal better if the horn is still attached with a seal of hide. If it is broken and dirty it becomes less likely that the repair will be successful. Go ahead and wash out the dirt and proceed.
Bend the rebar to the shape of the top side of the horn spread. (see ilustration below) Roll the soft undies in a ball and place them right on top of the pole. Place the rebar on top of the undies. Start wrapping the casting material around the good horn which will pull the rebar up above the bad horn. Put one full roll (rolls are about 4 foot long) around the rebar and good horn all the way from the head to the end of the rebar. The casting material will dry in a few minutes.
Start a second roll of casting material around the broken horn and draw it up to the rebar (like a spring) to pull it up into correct placement. Wrap it from the head to the end of the rebar. Then take 2 or 3 more rolls and figure eight it back and forth all over the top of the head connecting all the material together. Totally cover all the rebar and undies water tight.
Don't let the critter lose until the casting dries. Then put it where other critters won't butt heads for 3 to 4 weeks.
If the material stinks or bleeds in the next two weeks it means you did not get it soon enough or it had dirt in the break. You will notice the critter walking like a drunk with a hang-over and a busting head ache. All is lost. Call a vet.
If you succeed the critter will act healthy, eat well and act normally. Put it in the chute at about a month. Saw right into the middle of the rebar into the undies and cut the cast in half. Pull it off the horns away from the head and you have won the war.
The younger and shorter the horns the easier.
I cast the famous bull Bail Jumper. If you look close at photos you can see where the break is, but if you don't know it you wouldn't guess it.
When I used to show a lot I always carried the 3 items to every show. It doesn't happen often, but being ready is the most important thing. All ITLA members should have the materials ready. It only takes one prepared person per show to save the day.
Good Luck. Darol Dickinson