Why Do Big Dogs Live Less Than Small Ones?

Why Do Big Dogs Live Less Than Small Ones?

A dog as big as a Saint Bernard does not usually reach 10 years of life, however, a small chihuahua reaches 15 years of life without problems. What are the reasons that big dogs live less?

In the animal kingdom, size usually equals longevity, since normally, large animals such as elephants or whales can exceed 60 years of age and a small animal such as a mouse only lives one or two years or a butterfly that he comes to live only a few months.

In the world of dogs, it is totally the other way around, since big dogs live less than small dog breeds.

Some of the possible hypotheses that the scientists give are:

1. Big dogs jump more, run more and may wear out their body more quickly than small ones.Why Do Big Dogs Live Less Than Small Ones?

So, big dogs usually lead harder lives than small ones. Since they Big dogs run more, they jump more and they may wear out their body faster than the little ones. Also, if we compare the wear of a working dog, dedicated to pulling sleds or grazing, with a small dog that is dedicated to being at home and take short walks, the theory can fit us, and it may be one of the reasons why what large dogs live less.

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2. Large dogs are more likely to develop cancer.

According to medical research, Large dogs are more likely to develop some type of cancer, especially bone cancer. This could be another factor that affected the life expectancy of our big dogs.

3. Large dogs have a small heart.

Another possible theory may lie in the difference between the body mass of a large dog and the size of its heart since in proportion, big dogs have a smaller heart than small dogs. It may be that this makes the hearts of big dogs live less because they suffer more and wear out earlier than that of smaller dogs.Why Do Big Dogs Live Less Than Small Ones?

4. The fault could be oxygen free radicals.

Speaking now scientifically, according to current research by a team of students at Colgate University in Hamilton, New York.

Oxygen free radicals appear as a waste of the process by which cells obtain energy from food. They are molecules that have lost electrons and try to recover them by removing them from other cells in the body, “oxidizing” them in the attempt. The body generates “antioxidant” molecules that neutralize them, but the more energy an organism produces, the more free radicals escape to harm.

This metabolic process seems to be one of those responsible for the aging and deterioration of the body and could explain why big dogs live less and usually die before smaller ones.


This happens because puppies of large breeds have rapid metabolisms that consume an amount of energy much higher than that of small dogs. This imbalance causes damage to the cells that will appear in a few years and will shorten the life expectancy of big dogs.