Bell boots are for what is known as interference (which goes by several different names depending on which legs are hitting each other. Ex. forging, brushing, etc.). Interference is when the legs come into contact with each other and cause cuts and abrasions from the tough hooves hitting the not-so-tough flesh of the coronet, heel, and pastern area.
They protect the horse's leg from the fetlock down on the backside. Horses who are being asked a lot will often clip their back legs on their front legs, or their front legs together. Posted via Mobile Device
Here is a good reason to use bell boots.
Showed in the stock horse day before yesterday, making a turn on the fence on a tough cow my horse pulled off both bell boots.
These aren't the cheap pull-ons. These are the heavy duty gum rubber ones that you break into a good sweat to pull over a horse's shod foot.
Well worth the money to save heel bulbs and pasterns in my opinion.
I was in a huge hurry and ran without bell boots ONE time. That's what happened.
I have videos of my horse ripping bell boots off and seeing them fly across the screen, or finding them on the backside of barrels, or at random places in the arena. Working cows that happens to me a lot as well. She's growing out of it and isn't ripping them up quite so bad these days, but I still won't ever take the chance again.