Most animal geeks have heard that one human year is equivalent to seven dogs years, but the 1-to-7 ratio is not entirely accurate, however, as dogs of different breeds grow at varying rates. While larger breeds usually have shorter life spans than smaller breeds, they also reach physical maturity more slowly than their smaller counterparts. For instance, a Great Dane will be fully-grown at around 2-years of age and a Yorkshire terrier will reach full adulthood in approximately 1-year. Continue reading for more before and after images.
[Source]
