Large dogs live much shorter lives than small ones. Researchers believe they have found the answer to the mystery

Size matters. Of course it matters. It matters in many things, but especially in longevity. Because it is no coincidence that a bowhead whale live to be 200 years old, while The common fly lives, on average, 28 daysIt is almost a “law” of zoology: small animals tend to live fewer years than large animals.

And yet, this doesn’t happen with dogs.

And what about dogs? It’s funny because, although we usually talk about the “life of dogs” as something homogeneous and expressions like “dog years” are very well known, but precisely in dogs the situation varies a lotTo give you an idea: the life expectancy at birth of some breeds can double that of others.

And the worst off are the big dogs. In fact, body size is the best predictor of life span in domestic dogs. The question is why.

There are thousands of theories. However, not all of them make sense. For example, Silvan Urfera veterinarian who works in the Dog Aging Project from the University of Washington, explained in National Geographic that those that relate it to inbreeding do not seem to make much sense. Not only because there is nothing that makes us think that there is more inbreeding in small breeds than in large breeds, but because The difference between mixed breed and purebred dogs is just a few months old.

Other theories relate this difference in life expectancy to things like dental healththe obesity or the cognitive developmentHowever, none of them has managed to comprehensively (and effectively) explain the problem.

So? Researchers at the University of Washington are working on another hypothesis: that growth is to blame. Let’s think about it this way, the size difference between breeds is also twice as large. “An adult Newfoundland lives between 9 and 10 years and weighs up to 70 kilos. A Chihuahua lives between 14 and 16 years and weighs 3 kilos,” explains Urfer.

This has led them to believe that large dogs have a huge amount of growth left to do, and that development can end up causing damage at the cellular level: from the loss of telomeres to greater oxidative damage. In essence, it means that large dogs age faster (and develop age-related diseases earlier).

Why does this happen to dogs? The reason, According to researchersIt’s simple: they are one species. When we compare giant tortoises to tiger mosquitoes, we are comparing different species with completely different phylogenetic histories and evolutionary adaptations. But when we talk about German shepherds and Maltese bichons, we are talking about the same genetic mechanisms working in very different ways (and much more).

It stands to reason that, in some ways, they work better in one context than in another. And it seems that size is one of the contexts in which this is most noticeable.

Image | Mahmoud Ayad

At Xataka | Solving one of the big questions about pets: whether they are good for our health or not