Advertisement How does a dog “accidentally” run a half marathon? Great question! It’s actually pretty simple and straightforward. And hilarious. Mostly hilarious! A half marathon is 13.1 miles. Something I doubt Ludivine, the two-and-a-half-year-old Bloodhound knew anything about before accidentally “competing.” The “accident” part comes into play because Ludivine’s owner didn’t run or participate in the race. Ludivine got let out to use the bathroom on Sunday and somehow ended up at the starting line of the Elkmont Trackless Train Half Marathon in Alabama.