tor - a prominent rock or pile of rocks on a hill. rock, stone - a lump or mass of hard consolidated mineral matter; he threw a rock at me.
To become an equine veterinarian, you must obtain a Doctor of Veterinary Medicine (DVM) degree from a college or university accredited by the American Veterinary Medical Association (AVMA). A DVM program takes four years to complete.
I wouldn't think the average was 50 - some equines have been known to live into their 50s but it's pretty rare. This article says that minis average 25-35 years.