In comparison, does the standard 7 years to 1 of a human still measure up in dog years? It seems not, at least not anymore! Animal scientists have known the "dog year" ratio to be flawed, yet the 7 year myth remains. Where did the idea of dog years originate in the first place and why do scientists disagree with the math?
Dog Year Origins
The "7 year myth" origin is shrouded in an enigma not even Scooby-Doo and Mystery, Incorporated would be able to solve! Some say an inscribed 'Judgement Day' computation etched at Westminster Abbey in 1268 proclaims a ratio of 9 to 1, meaning humans live to 81 and dogs live to age 9. An 18th century naturalist, Georges Buffon had a theory along the same lines: Humans live into their 90's or up to 100 and dogs live to 10 or 12.
The 50's Standard
Then sometimes in the 1950's the idea emerged that humans live around 70 years and dogs live to 10. This was an easy translation that somehow became a standard of sorts for dog owners to calculate their pets human age. Veterinarians most likely adopted this '7 year rule' as the truth!
William Fortney, a veterinarian at Kansas State University, told the Wall Street Journal that the 'rule' probably was a marketing trick; a way to educate the public on how fast a dog's age advances as compared to a humans age, predominantly from a healthy standpoint. This was a method devised to encourage owners into bringing their pets to their vet's office for yearly check ups.
Doesn't Add Up
If you think about the 7 year rule, you'll discover that the math doesn't add up at all! "If this ratio had any truth to it, reports Carl Balik of The Wall Street Journal, "humans would be capable of reproducing by age seven, and high percentages of us would live to be 150."
Size is a Related to Lifespan
The first year of a dogs life is, in actuality like 12-15 in human years because dogs usually reach sexual maturity within that first year. By their second year dogs are fully mature. What complicates matters are the smaller breeds who mature even faster than larger dogs. In 'Dog-Dom', unlike the rest of the animal kingdom, size is inversely related to life span where dogs live between 16 to 18 human years and smaller dogs outlive larger dogs. Calculating your dog's age is no longer a case of simple multiplication since dogs age faster in their early years and slower in their later years. Aging expert David J. Waters explains simply , "Eight years in one breed is not equivalent to eight years in another."
Advanced years in dogs (as in humans) bring changes in a dog's ability to hear, see and even move or stand. Certain skin conditions appear. Energy levels decrease as does appetite. Sleeping time overtakes play time and serious medical conditions may arise with age. The age at which dogs become geriatric averages to around 11 years of age for small dogs, 10 for medium, 8 for large and 7 years for giant breeds.
Weight Determines Size
Your dog's weight plays an important factor in determining your dog's age because weight determines size:
20 pounds or less equals small (ex. chihuahuas, toy poodles.)
21 - 50 pounds equals medium (ex. labrador retrievers, bulldogs.)
51 - 90 pounds equals large (ex. Afghan hounds, Irish setters.)
Over 90 pounds equals giant breeds (ex. Great Danes.)
Click here for a handy-dandy chart that will help you figure your dog's approximate age.
A Sad Truth
Even with new charting and knowledge concerning the life expectancy of all breeds, there is one thing we know for certain - a dogs life isn't as long as we'd want it to be - and that's the sad truth!
By Tom Matteo