What was that..?

Walking Dottie on the moor today and this border collie appeared over the horizon. His owner appeared a few minutes later, during which he ran rings around Dottie. His name was Kensey, six months old and bursting with energy. Too much hard work for me... Dottie and I continued on our way rather sedately, but those few minutes of intense activity did it for Dottie. She has slept since we got back!