depends what ground you ferret. Jack russells are good some like whippets. I prefer beddy whippet and wouldn’t want anything else. ground I frequent is hedgerows, railway embankments etc. the one I work now at 18 1/2 inch she tackles brambles, nettles, is a excellent marker and is quick enough for short 20 or so yard bolters. but I certainly wouldn't call her a running dog.