The horse on the left shows bite marks on its back. Horses often bite each other in playfulness. A horse’s skin is not as sensitive as a human’s. The hair will grow back.
These Exmoor ponies were pretty comfortable in their winter hair coat out there in the open field, while my fingers were freezing off handling the camera. You may bring your comfy, fingerless mittens to the job but when you forget to put them on because you are too preoccupied making pictures of these definitely smarter animals it becomes a horse and water thing with roles reversed.