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. The natural life span of the border collie is between 12 and 15 years, with an average lifespan of 12 years. The median longevities of breeds of similar size are usually 12 to 13 years. Leading causes of death are cancer (23.6%), old age (17.9%) and cerebral vascular afflictions (9.4%). The use of dogs for herding sheep makes good economic sense for many farmers. Attempts to replace them with mechanical approaches to herding have only achieved a limited amount of success. Thus, stock handlers find trained dogs more reliable and economical.