The "Patagonian Sheepdog" is a local working dog breed that was produced by selection from European working sheepdogs that arrived in the Magallanes region of southern Chile in the late nineteenth and early twentieth centuries. Currently, the Patagonian Sheepdog is most commonly found in the Chilean Patagonian region (43 degrees 12' S to 56 degrees 30' S), where it plays a fundamental role as a working dog in sheep and, to some extent, in cattle farming. Dog types that may have contributed to the Patagonian Sheepdog include the Old Welsh Grey and other old UK herding dogs. The modern Patagonian Sheepdog has been selectively bred by local sheep farmers to produce a herding dog that is well adapted to the area: a medium body size, long or semi-long fur, drooping or semi-erect ears, a docile character, and a great aptitude for sheep herding. Morphological studies have determined the body measurements, zoometric indices, coat color, and marking for Patagonian Sheepdogs. The objective of this investigation was to collect historical information related to the presence of this dog in Chilean Patagonia, providing general aspects of the morphology and behavior, all key factors for the recognition and conservation of this little-known herding dog.