Neither rain nor snow nor horse/pony can keep a border collie from his appointed rounds herding sheep. Red herds alongside donkeys, other dogs, horses grazing, in the rain, snow, wind, cold and heat. He has a natural kind of laser built into his head, he stays focused no matter what. To my knowledge, Red had never seen or worked with a horse before, but almost all animals react to his calm and professionalism.
Chloe is happy to graze while Red works, the two have worked out an easy and trusting relationship.