Everyone has either seen, pet or owned a dog in their lifetime. There are even dog shows on T.V. for “Pure Bred Dogs”; which is funny because they all eventually descended from ancient wolves, but that’s a different story. Selective breeding is how many pure bred dogs are achieved, however, by doing this people not only changed the breeds looks but led to some health problems. Listed below, there are several dog breeds with their changes over the last 100 years.