The notion of dog years stems from the common belief that one year for a dog equals seven years for a human. Although canine aging is more nuanced than a simple formula, any dog lover knows that dogs' lives pass far too quickly.
Even so, America's 70 million dogs, like their human companions, are living longer, on average, because of better medical care and nutrition. Caring for elderly dogs can be heart-wrenching. Many pet owners struggle to understand when to pursue aggressive care and when to stop and help a beloved pet pass on.