It always seems to me like a dog ages in behavior/personality (capacity?) in the following way:
0 – 6 months upto a human 1 year old
6 months – 2 years – human toddler (2 – 4 years old)
2 years - 5 years human teenager
5 years - 9 years human adult
9 years on – human senior
What have you found?
This is an excerpt that I found from an excellent and fun article. Gayle did a nice job on this.
By Gayle Hickman
Aging is much faster during a dog’s first two years but varies among breeds. Large breeds, while they mature quicker, tend to live shorter lives. By the time they reach 5 they are considered “senior” dogs. Medium-sized breeds take around seven years to reach the senior stage, while small and toy breeds do not become seniors until around 10.
Many veterinarians agree that a pretty good guess on the age of pets can be made using the following formula. Although still simple, it is much more accurate than the seven-year method.
Assume that a 1-year-old dog is equal to a 12-year-old human and a 2-year-old dog is equal to a 24-year old human. Then add four years for every year after that. (Example: A 4-year-old dog would be 32 in human years.)
Since this method takes into consideration the maturity rate at the beginning of a dog’s life and also the slowing of the aging process in his later years, Martha Smith, director of veterinary services at Boston’s Animal Rescue League, feels that this is the more accurate calculation formula. Here is a chart, for easy reference:
A dog’s average lifespan is around 12 or 13 years, but again, this varies widely by breed. The larger your dog is, the less time it will live. Female dogs tend to live a little longer.