Why do smaller dogs live longer than bigger breeds?

Biggest is not always best...
08 August 2017



Why do smaller dogs live longer than bigger breeds?


Chris asks Sarah Harrison from the University of Cambridge why smaller dogs live longer than bigger breeds?

Sarah - Absolutely it’s the case.  I think that’s why this makes a great question because, as Michael says, larger mammals tend to live longer, so elephants tend to live a really, really long time. But when you look within species, the trends almost reversed and this is why, as Michael points out for dogs, if you are a larger dog, you tend to have a shorter lifespan than a smaller dog.

It’s not just dogs, this trend holds in humans as well. The tallest every human that’s ever been recorded to have lived was about 8 ft. 11, but this poor chap died at 22 years old so being large didn’t gift this poor guy with longevity.

Chris - Those people are obviously a little bit exceptional aren’t they because something made them become extraordinary big compared to the norm, but going back to the original question about dog size,what is the reason why a bigger breed will be outlasted by a smaller breed?

Sarah -  We don’t know the full answer to this and we think the reason behind this is because larger animals grow a bit faster. This means they’ve got a higher resting metabolic rate so they’re exposed to more reactive oxygen species that can lead to DNA damage. The other thing is these animals have a lot more cells in each of their organs which means more cells have a higher chance of getting some kind of somatic mutation that might lead to cancer or tumour regenesis.  But, as I say, the full answer is not known.


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