Per information on the National Trails website -
After three tragic deaths and several injuries this year the National Farmers' Union has issued advice to walkers, especially those with a dog. To keep you and your family safe, we strongly advise you to read and follow this advice.
The most important piece of advice is to let go of your dog's lead if cows attack, then make your way safely out of the field before calling your dog.
If you encounter aggressive cows or are chased by cows please phone the Health and Safety Executive's Incident Report Centre on 0845 300 9923. They log both reportable and non-reportable incidents. A reportable incident is one that results in someone needing hospital treatment, a non-reportable incident is a near miss. This helps to establish a more informed picture of what is happening in the countryside.