Why do dogs have such short lifespans?

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We talk a lot about improving your dog’s life span by making sure he is healthy and fit through exercise and proper nutrition. Many of us do what we can to help them live longer by following these guidelines. But if dog’s are man’s best friend, and I would certainly argue that they are, why, oh why, are their lifespans so short???
dog life spans

The average lifespan of dogs range from 7-8 years for some large breeds like a Great Dane or Mastiff to 14-15 years for smaller breeds like Miniature Poodles or Dachshunds. Labradors like Jack & Maggie fall in the middle with an average life span of only 12.5 year.
I did some research into why their life spans are so short, but found nothing that really provided me with any insight or answers to my question. I did find some interesting information on the the “Rate of Living” theory. This theory states that the faster the metabolism of the organism, the shorter their lifespan. Animals with slower heart rates, like elephants and whales, tend to live much longer lives. It’s not really about the size of the animal, but about the number of heart beats – most animals get about 1 billion heart beats in their lifespan, so the faster the heartbeat, the quicker those heart beats are used up and then…the heart stops beating.

Runner's World April 20, 2013

Runner’s World April 20, 2013

Humans are the only mammal that don’t fit the mold. Here’s an interesting chart from an article that appeared in Runner’s World. You can see humans are way out of whack to the 1 billion heart beats theory with almost 3X as many beats. But as the article states, humans have benefited from advances in science, sociology and medicine which has allowed us to extend our lifespan considerably and likely accounts for that discrepancy.

But, circling back to my question about dog’s short lifespan, we do have some evidence that they are beginning to benefit from those medical advances. Between the 1950s and 1960s, pet care in America had made so much progress, that the average life expectancy of cats and dogs had increased by two to three years 1. So, while I didn’t find a specific answer, it seems that their life span is normal relative to that their fellow mammals. Here’s hoping that the trend for a longer life span seen in the 50’s – 60’s continues and our beloved pets stay with us longer and longer.


1. The History of the ASPCA
Additional Readings:
Rate-of-living theory
How Many Heart Beats Do We Get?
Size Matters: The Hidden Mathematics of Life

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  1. Yes, the short lifespan of a dog is the ONLY thing I hate about them!!!
    I’m doing my very best by providing daily exercise & healthy nutrition to keep my pups around as long as possible. One of my Great Dane client pups just turned 10 years old (that’s already pretty old for a Great Dane!), while one of his sisters crossed over the rainbow bridge at age 8 last year. It really sucks that larger breeds have a fairly short life expectancy.
    Barbara Rivers recently posted…Comment on Kibble vs. Raw: An Experiment by K9sOverCoffeeMy Profile

  2. What we all wouldn’t give for more time! Pet trends follow human trends, so hopefully as we better understand anti-aging mechanisms we can pass along the benefits to our pups.

  3. As Sam is now over 10, I too hope he is fortunate enough to stay with us as long as possible. Thinking of life without him is simply incomprehensible though in my heart I know that reality will be eventual.

  4. It really is a dog’s only fault but we all know that when we welcome them into our hearts. I have had to say good-bye to six dogs as an adult and there is no way to ease that pain. We just have to love them and hope that veterinary medicine continues to advance. The heartbeat information makes sense.
    M. K. Clinton recently posted…Baby, It’s Cold Outside for PetsMy Profile

  5. So now I’m thinking I should give up on cardio as it causes my heart to beat faster, thus shortening my life. It does make sense in general with the heart rate, but still it is not fair for dogs to have such short lives.
    Emma recently posted…French Scent Hound Meets French RabbitMy Profile

  6. This may not make sense – but I know you’ll get it. After losing Leo I cannot breathe at times when I think about life ww/o Harley. His physical departure will break me forever. I cringe at just the thought. He’s got to defy the odds and hang on twice his life span 🙂 My sanity depends on it!

  7. This has always been in the back of my mind since I brought home Linus. He’s an aussie mix and still going strong at 11 years old.

  8. I always thought Daisy would be like 13 or 14 because she was in amazing shape. I heard a quote that said that the only thing wrong with dogs is they don’t live long enough. I want to do everything I can do to keep Cocoa Bean healthy and happy!!
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  9. This niggles at the back of my mind all the time, as I watch Sampson slowing down, sleeping more and creeping closer to the age of 12. I’m not sure what the answer is, all I know is it simply isn’t enough time. It isn’t.

    The one thing that gives me hope is the vet said by helping them lose the extra weight, we have probably added 2 to 3 years to their lives.
    Jodi recently posted…Funny and Sad…Life with Old Dogs – Barks and BytesMy Profile

  10. Oh, I get tears in my eyes just thinking about losing Haley and I’ve shed countless tears while reading about Maggie and so many other pups out there that are battling cancer and other illnesses. It’s so tough to even think about losing them.

    That’s why we dog lovers celebrate every day with them and spoil them a little too. 🙂
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  11. You’ve hit upon something that has fascinated me for years. If you compare all mammals, generally larger mammals live longer than smaller ones. However, if you compare within species with a very large size range (like dogs or horses), the opposite is true. The smallest ones live the longest.

    It’s all part of the field that looks at “scaling”, which involves how various physiological and biomechanical factors change with body size. I’ve always thought that the opposite trends for mammals in general and for dogs specifically would be a fruitful area to explore to understand better what determines an animal’s expected lifespan.

    Fascinating topic!
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  12. Animals have shorter life spans so that many can come into our lives and share their love with us. 🙂
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  13. I’ve only ever found one blessing to the short lifespans of my dogs. It has allowed me to love so many more of them.

    I’ve had six dogs in my life. I can’t imagine raising them all at once (especially not on a boat). So if I could only have one or two for 40 or 50 years, which one would I choose?

    Yes, saying goodbye is heart breaking. But it’s worth every tear.

    BTW, I would have loved to have seen where large birds fit on that chart. I’ve heard of parrots living a lifespan comparable to humans.
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  14. I think in the end it all boils down to genetics. I agree that smaller dogs tend to live longer than larger ones but I have know large dogs who made it well past life expectancy and usually it is carried through their lineage (exceptions occur of course).
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