This is false logic. Dogs are living longer today because of improved social status and advances in medical care. "Back in the day" dogs were not considered the valuable family members and companions they are now. Dogs were left outside to brave the elements. They were guardians of house, possessions, and livestock. Dogs had a purpose, a job, and when they could not do that job, they were retired or disposed of. Medical care for dogs was scant and typically unimportant, as more prestige was gained from being a livestock vet than a canine vet. Very little notice was given to the dog's health as long as it could still do what was asked of it.
Nowadays, dogs enjoy a better life, one that is easier and less taxing (except for the great injustices that are kibble and excessive vaccination). They sleep inside with their owners. They enjoy the social status of family companions. People care more about their welfare. They receive the benefits of improved health care—much of which has evolved in the last 50 years because of the ailments caused by processed foods—and the added bonus of people caring about them receiving that care. For example, 100 years ago people would have never paid thousands of dollars to give their dog a hip replacement, or hundreds of dollars to get routine dentals performed on their pets. Nutrition has had a very negligible role to play in increased longevity other than the fact that dogs are no longer starving and do not have to hunt or scavenge (both of which are energetically costly). Instead of contributing to longevity, these "nutritional advances" have contributed to more and more health problems previously unheard of in dogs—diabetes, various cancers, inflammatory bowel syndrome, and bloat, for example. Veterinary medicine has evolved into 'modern veterinary medicine' because of the increasing prevalence of processed food-related diseases and the need to treat and fix them (which often involves switching your dog onto a higher-priced "therapeutic" processed diet). Granted, these diseases are diagnosed more frequently today because people actually know what to be looking for, but the amount of dogs suffering from these ailments today as opposed to earlier dogs indicates a VERY strong link to the foods they eat, links that have been proven to exist between humans in developed countries and processed foods.
What about increased longevity? Dogs' longevity has only recently been determined by 'research' performed by the pet food companies. They use these estimates to "show" that their food helps animals live longer. But longer compared to what? No one cared about canine longevity in the earlier days (except the select few concerned with breeding canines), so no one kept records or performed surveys. So this longevity estimate is only valid from when the surveys started. Indeed, kibbled food has been improving from the early prototypes that created a variety of nutritional deficiences (like overgrowth and bone malformations in puppies; this STILL is a problem.), but this "nutrition" has not contributed to longevity in nearly the same manner that increased social status has.
In reality, canine longevity and quality of life has been decreasing for many breeds since the advent of processed food. People who remember the 'old days' when dogs were fed raw meaty bones often report their dogs living well through their late teens. Nowadays it is a "miracle" and a testament to the "excellent nutriton" the dog must have received, and vets and pet food companies claim this "miracle" as occurring often enough to become 'commonplace'. Too bad most of the vets who remember the good old days have now retired or even moved on. It seems this new generation of veterinarians will know nothing but kibbled, processed food and the ailments induced by it.
So they say dogs are living longer. And indeed people can step forward and say they have 16-year-old Golden Retrievers and 14-year-old German Shepherds and 11-year-old Great Danes. But what about the quality of life for these old dogs? They have horrible teeth and rancid breath, severe arthritis or degenerative joint disease, cancerous or benign tumors, diabetes, kidney failure, nasty greasy coats, and soft fatty bodies lacking muscle tone. People say this is just "old age" and that we see this more often nowadays because dogs are living longer. But is this really true? Many of these ailments are caused by or heavily influenced by a lifetime of eating processed food and developing periodontal disease and bacteria-laden teeth (Lonsdale, T. 2001. Raw Meaty Bones.). Those who remember the 'early days' remember long-lived dogs enjoying better quality lives until one day they just did not wake up. This slow, accumulating progression of disease is invariably linked with processed foods—something that has been proven time and again in human medicine and is being proven daily by the amount of processed food-fed pets suffering from a variety of these ailments and sitting in vets' waiting rooms.
If pets are living longer, then why are they being considered "old" at younger and younger ages? A dog is now a senior by the age of 7 or 8; some even say a dog is "old" at 5 or 6. Cats are considered seniors by the ripe old age of 7 (tell that to raw fed cats still going strong at the age of 20!). This premature aging is caused in large part by processed foods (Lonsdale, T. 2001. Raw Meaty Bones.). Cancer, diabetes, obesity, kidney failure, heart problems, and arthritis (among other things) are being seen in younger and younger dogs. Dogs 3 years of age are being euthanized for malignant, systemic cancers! What happened to this "dogs are living longer" claim? It is high time we stop slowly poisoning our beloved friends through commercial diets and excessive "preventative" health care measures!
TIDBIT: The oldest living raw-fed dog is Jerry, an Australian cattle dog-bull terrier mix. He is 27 and lives with his owner in Australia (Outback Mongrel Could Be Oldest Dog. USA Today. 7-13-2004.). To see the full text story, please click here (if this link does not work, please tell me; it may mean the story has moved elsewhere).