Founder isn't necessarily a disease of the horse, but a complication of many horse diseases. Founder occurs when a disease, such as laminitis, goes untreated for a long period of time, and most horses who founder are profoundly neglected. Founder occurs when the coffin bone sinks through the hoof frog, making standing and moving impossible without extraordinary pain. Most horses that founder will require constant attention and perhaps hospitalization in an equine clinic to heal.