We run our 7 sheep (3 Shetlands, 1 Heb and 3 Dartmoors) in with 3 horses - having watched carefully when they first went in together. One of the horses will chase the sheep away if they eat his pile of hay, but putting out several piles sorted that. We also run some electric tape around the field shelter, so the sheep can run into a protection zone if necessary. We are about to put the sheep in their own field for a while now as we rotate the grazing (the horses have completely trashed one paddock over the miserable wet winter)