That's right! It's so unique that dogs do have their "Age chart"! Hah! So, how does dog age in related to human age? Well, scientificly speaking, dogs' organs develope and deteriorate just like human but at different rate over the time. That's why it is important to bring your dog for yearly check up once he or she reaches 7 years old onwards in human year besides the annual vaccination.
The body and organs develope rate in dogs are different compare to human. Take for instant, a female dog ( bitch ) reaches maturity for reproduction ( first season in heat ) when she reaches the age of six months old while human at the age of 10 or 12 years old. Another example is human normally reaches the golden age around 50 years old while a dog reaches old age at 7 years old in human year.
Seen here a 13 years old black and white Shih Tzu in short coat.
So, just how accurate is the chart ( below ) in human year? Well, unfortunately not so.... How so? Firstly, the lifespan expectancy and the rate of growth in defferent dog breeds are differ. Secondly, most of the commercial food nowadays are more well balanced in nutrition and more dog owners are educated in taking care of their dogs, hence all these are the factors in prolonging the dogs' longevity.
Below is the comparison age chart ( estimated ) between Human and Dog