The Border Collie is a working and herding dog breed developed in the Scottish borders for herding livestock, especially sheep. It was specifically bred for intelligence and obedience. It is very fetch-oriented. Eye color varies from brown to blue, and occasionally eyes of differing color occur; this is usually seen with merles. The ears of the border collie are also variable — some have fully erect ears, some fully dropped ears, and others semi-erect ears (similar to those of the rough collie). There is now a DNA test available for CEA and, through its use, breeders can ensure that they will not produce affected pups. There are different types of hip testing available including OFA (Orthopedic Foundation for Animals) and PennHip. Radiographs are taken and sent to these organizations to determine a dog's hip and elbow quality.