They might not look harmful, but farmers have warned walkers to be careful around cows with calves.
Three people in as many months have been killed and many more injured after run-ins with angry cows.
Cows try to protect their calves, and even attack people and dogs that they think might be a threat.
Walkers who do get in trouble with cows should first of all let their dog go, and should carry a walking stick with them at all times.
Farmers also advise being brave and just walking straight through the herd of cows.
It's thought cows see dogs as a threat, because they look a bit like wolves.