If dogs have a flaw, and I realize many would argue they do not, it is they don’t live long enough. I think many would agree that a dog lifespan of 40 or 50 years would be perfect, so that you could have the same best buddy for your entire adult life. In the past few weeks, there have been two interesting scientific publications on longevity in dogs. The studies’ conclusions and impact on your dog will be the topic of this blogpost.

“Dog”ma About Longevity

There are two common mantras regarding canine longevity. The first is that small dogs live longer. The second is that mixed breed dogs are healthier and live longer than purebred ones. Let’s discuss…

I think it is a fairly common belief that small dogs live longer than big dogs, and this is supported by data. In a study of breed-specific longevity, the miniature poodle was the longest-lived purebred dog studied between the years of 1980 and 1990. More recent data confirms the longer average lifespan of smaller sized dogs.

The second mantra, that mixed breed dogs are healthier and thus live longer than purebred ones, is also backed by data. In fact, a 2023 study showed mixed breed dogs lived longer than large and giant purebred dogs. The greater longevity of mixed breed dogs has often been attributed to “hybrid vigor” or the increased vitality of offspring combining the best of two very different parents. The newly published studies put a new spin on these “dog”mata.

Size-Related Canine Diseases

Lifespan is in part determined by the diseases we contract. In dogs, large and small breeds develop different diseases. Recently published work by the Dog Aging Project, and supported by information in AMC’s Pet Health Library, shows large dogs are more likely to develop cancer, orthopedic disorders and tummy troubles. These conditions differed from those prevalent in small dogs, who were more susceptible to problems with their eyes, heart, liver, pancreas and respiratory system. For diseases of the urinary system, there was no difference in occurrence based on the size of your dog. This list should help dog owners monitor your dog and help catch potential illnesses early.

Long Noses Live Longer

The modern dog is probably the most varied species on the planet, ranging from 2 to 200 pounds, and has equally diverse physical appearances, personalities, behavior traits and lifespans. A recent study of over half a million British dogs looked at skull structure as one parameter related to longevity. Various breeds were assigned a cephalic index, which is a ratio of the skull’s length to width. In scientific words, dogs with a low cephalic index are brachycephalic (think “snub-nosed” like a French bulldog); dogs with a high cephalic index are dolichocephalic (think Lassie the collie) and those in the middle are mesocephalic. Gender, size, and cephalic index were closely intertwined with longevity. For every combination of gender and size, low cephalic index (or brachycephalic) dogs were shown to have a shorter lifespan. Whether dogs in countries other than the United Kingdom have similar lifespans remains to be confirmed.

The True Age of Your Dog in Human Years

Want to know how old your dog is in human years, really? Read a prior blogpost to find out how to calculate your dog’s true human age.