The FCI divides dog breeds into 10 different groups. For laymen, however, the size of the dog is more likely to play a role in the purchase of a dog. For this reason, dogs are often distinguished between small, large and medium-sized breeds on the basis of shoulder height.Among the medium-sized dog breeds are those whose shoulder height ranges from 40 to 59 centimetres. Weight and appearance can vary greatly. For example, the Beagle with a weight of nine kilos or more is a medium-sized dog, as i..