JWT has alerted me to this account of a dogwalker trampled by cows in England, and sees this as another mark in favor of owning cats. He's got a point in that no cow would ever make it through those little door flaps.
From the Story Highlights: "Experts say it's very unusual for people to be killed by cows." Can't argue with that. There's also helpful advice about what to do if you're walking a dog and feel threatened by cows. I guess my advice would be "stay the hell away from cows" but perhaps the North of England is not sufficiently expansive.