Walking the dog isn’t always a peaceful outing. Sometimes there’s actual danger out there, both for your dog and you. When thinking about this, you probably tend to worry most about other, more aggressive dogs.

But if you live in farm country, there’s another aggressor species to avoid running into, at least at certain times of the year: cows.

Yes, cows. In Britain, they’ve trampled four dog owners to death in the last two months, Reuters reports.

Robert Sheasby of the National Farmers Union says  the cows are going after the dogs rather than deliberately attacking the humans, but, of course, “there’s a high chance they will get the walker too”.

Why do these placid farm animals turn violent? We’re used to the idea of Mama Bear as a creature to fear, but Mama Cow? We’re also used to the idea of bulls being aggressive, but we’ve come to expect more self-control from the female of the species. (Though my mother has told me that, as a farm child, she hated the chore of bringing the cows home from pasture because, if they met another herd, they would fight.)

Motherhood is what does it, the NFU explains. In summer, as well as fall, many cows have one- or two-month old calves around, and they’re feeling very protective. When they see a carnivore running toward them and their children, they don’t know if it’s there to herd them away, hunt fresh veal, or just take a stroll, but they don’t take any chances.

The NFU advises people to let their dogs off the leash when they go through a field of cattle. This should at least make it easier for the human to escape if needed. Maybe the safest option for both is to stay away from cows altogether.