Border collie belongs to large dogs or medium-sized dogs can be distinguished from medium-sized dogs and large dogs?

The Border Collie is a medium sized dog The Border Collie is a normal medium sized dog with a very well proportioned, medium sized, robust looking dog. The grace and agility displayed is commensurate with the physique and energy. Its solid, muscular body with a smooth profile gives the impression of effortless movement and endless stamina, a trait that makes it the number one ranked sheepdog in the world, thus classifying the Border Collie in the medium-sized category based on its shoulder height and weight.