Different dogs enter old age at different times and many factors play a part in determining when your dog will become a senior citizen. Some of those factors include your dog’s health throughout his life, how active she is, whether she’s overweight or not and what breed he is.
The general rule of thumb is the last 25% of your dog’s life is considered his senior years. Since different breeds have different lifespan expectations, the year your dog enters old age depends on his breed. Below is a chart of the 10 “favorite” breeds of dog (according to AKC) their average lifespan and, therefore, when they are ready for their doggie AARP card.