Mackenzie
Old Brightonian
Yes and no. A splint bone injury can be treated, but other leg bone injuries are more difficult. A horse can't take the weight off of its leg, they don't heal.Broken legs can be treated but horses are a commodity that have to be earning. If they can't race then it's easier to shoot them.
Our old commodities have either been re-homed or are living the life of riley with muggins here at their beck and call....although as you say it would have been much easier, cheaper, less time consuming and ultimately soul destroying to shoot them.