It gives you just a little pause when you see a madly sprinting greyhound coming right for you. Stand still and you are OK, they will go right by. (Usually. My friend with the shattered ankle will argue that point after being taken out by a pack of greys who weren't paying attention.) Move and you're done for. The best part of having one that likes to do run-bys is that you get to see what they look like coming right at you. Looks a little off her rocker, doesn't she?