I've read a lot of reports recently and even heard someone say that it's 'cow trampling season' when lots of walkers/runners get trampled/kicked etc. Must be because they have calves. I think the best thing is to stay away or move away quietly and slowly. Lots of dog walkers have been atacked and the worst thing they can do is try to save the dog, although that must be instinctive but your dog can run faster than you and the cows anyway. I'm wure I've read something about this in a James Herbert book?