Very little is actually understood about dog aging because there is such a tremendous variance in life expectancy for dogs. Great Danes have a life expectancy of eight years of age. In contrast, a miniature poodle could potentially live up to 20 years or more. The oldest dogs have approached 40 years of age, but this is also somewhat negligible because it’s impossible to determine with accuracy whether this was actually their age (after all, they probably didn’t have birth certificates).
Life Expectancy and Maximum Age
The maximum age of a species and its life expectancy is not the same thing. Mankind has had a general life expectancy of between 50 – 70 years for the majority of our existence.
Though our life expectancy is between 50 and 70 years, the maximum lifespan of a human has always been around 110 years. That’s the maximum amount people are known to be able to live to. We have never been able to increase this, but it has stayed static; there are reports of people living to 110 from biblical times and on.
Longevity treatments generally serve to reduce aging, not increase lifespan. They help to ensure that people live up to the maximum rather than extending the ceiling. Thus, the average life expectancy of a Border Collie may be between 12 to 16 years of age. Still, we know from records that the maximum age of a Border Collie (or at least a BC mix) is up to 38 years old.
The Role of Breeds
Why Do Smaller Dogs Live Longer than Larger Dogs?
This is a fascinating question because the answers are not what you might traditionally expect. Most of the answers given by individuals, online and otherwise, actually don’t really make sense.
Larger dogs tend to die earlier than smaller dogs. Of all things about aging, we know this one best. Dogs have significantly been affected by breeding, and larger dogs such as Great Danes and Saint Bernards are, with all respects, larger than the species was ever intended to grow. Their cardiovascular systems, heart, and lungs, must operate with higher intensity and thus simply wear down easier.
However, it’s not merely an issue of size. Were it an issue of size, elephants (lifespan of 60 years) would never outlive mice (lifespan of 2 years). People tend to simply say, “large animals require more effort to survive” without really thinking about this point. In fact, the ultimate answer may simply be that larger breeds of dogs were tampered with, genetically speaking. Wild dogs tend to be around 30 to 40 pounds; dogs that exceed this weight have been bred for appearance, weight, disposition, and many other factors that notably did not include breeding for longevity.
Why are smaller dogs exempt from this? Small dogs–companion dogs, not working dogs–have been bred towards longevity, whether consciously or not. Everyone wants to have a companion that is intelligent, long-lived, and healthy. Furthermore, the genetic alterations may not have been as severe. If you take a 30 to 40-pound dingo and make it smaller, it will have issues with its teeth and nails, something that many “mini” breeds have to this day. However, these issues aren’t fatal. If you take a 30 to 40-pound dingo and make it a 120-pound beast, then you will have heart and lung problems.
It should be noted that dingos, when brought into captivity, often live up to 24 years of age. While it would be impossible to draw distinct conclusions from such a vague subset of data, it could very well be that dog lifespan today is chiefly determined by the amount and direction of human intervention.
The Role of Neutering and Spaying
Studies have repeatedly shown that neutered and spayed pets live longer. What they have not stated clearly is why. Statistics can be very misleading. People who take care of their pets and take them to regular vet visits are more likely to neuter and spay their pets, after all, and thus the neutered and spayed pets may be cared for more often.
At the other end of the spectrum, neutering and spaying in dogs is said to increase the possibility that the dogs will get cancer. But that’s not true; it’s correlation, not causation. The dogs that are spayed and neutered are living longer (whether due to spaying and neutering or due to increased owner care) and thus are living long enough to get cancer. Dogs remaining intact average 8 years old, whereas dogs that are spayed or neutered average 10 years–two extra years to get cancer, which targets elderly animals.
Thus, it’s not really possible to say what effect, if any, that neutering and spaying actually has upon an animal. Even the experts who ran these studies stated they weren’t clear on why the effect was, but some have theorized that it’s purely behavioral; animals not neutered or spayed will get into fights and roam more. Thus, again, the actual act of neutering and spaying doesn’t necessarily affect anything directly. A poor understanding of what impacts lifespan can only lead to further issues.
Purebred Dogs vs. Hybrid Vigor
It’s commonly known that mutts are healthier than purebred dogs. This is widely true because nature has a wide variety of genes to choose from, and the most successful one will be replicated. Purebred dogs are grown by humans and thus are bred for things other than health. In fact, some breeds are so intensely distorted that they have been labeled as cruelty in some countries. But that doesn’t mean that a purebred dog is necessarily unhealthy. Some dogs are bred for stamina, vigor, and health, such as working dog breeds. While other dogs are bred purely for “conformation” and appearances.
Hybrid vigor, itself, is often poorly understood. A mutt is not necessarily inherently “better” than either of its purebred parents. It merely has a wider genetic pool to choose from. Thus it has the possibility of getting the best of both worlds and neatly sidestepping potentially hazardous health issues. This doesn’t mean that a hybrid is magically healthier than either of its parents.
What, Exactly, Gets a Dog to Live Longer?
The question is something that may not be able to be answered. There are longevity supplements, such as resveratrol and probiotics, designed to increase a dog’s general health. Dogs that are taken regularly to the vet will be treated for potential health issues faster. Dogs that are overweight are almost definitely unhealthy, and many dog owners need to be educated on the proper weights for dogs. Certain breeds may be, unfortunately, doomed from the start.
Healthier diets and exercise can definitely contribute to a dog’s health, but even this is controversial. Some vets hate raw diets, others swear by it, and still, others don’t know anything about it–which is intriguing, because what did dogs eat until now? Dog foods don’t need to follow rigorous standards the way human foods do. Dogs can’t graze, so they can’t make up for any malnutrition in their diets the way people can follow their instincts. Multivitamin supplements may be useful but may not be adequately digested without help.
Does exercise help? Perhaps and perhaps not. Exercise might help purely insofar as it keeps weight off. After all, cats live longer than dogs and sleep about 18 hours a day.