Dog Friendly Tips: Horse fields
A field full of horses can be dangerous as the horses can excite each other and can run around madly, lashing out with their hooves at dogs.
A single horse, or maybe two horses, may be OK. My mother kept horses and horses that are accustomed to dogs will tend to be OK, though this is normally when their owner is around. A field full of loose horses with no owner around is a risk.
My own dog Jack was chased by a horse when we had no option but to cross a field with four or five horses in it. We were on a circular walk around the reservoir at Llangorse. Jack lost half a tooth from a well aimed kick. He was walking nervously to heel behind me at the time. The horses came up behind me and chased him around the field. Even though he was minding his own business he still got kicked.
We all beat a hasty retreat and had to make a long detour along a busy road, all because we had to leave our cross-country path through the fields and take the roads back to where we had parked.