Why Don’t Giant Dogs Live Longer?

Metabolism is a key factor in this quandary.

As puppies, large-breed dogs drive their metabolic engines pretty hard. By: Jay Iwasaki

If elephants live for 70 years, why don’t Great Danes live longer than Chihuahuas?

It’s an acknowledged fact that large-breed dogs don’t live as long as smaller ones. For example, here are some average lifespans:

Do the math and you can expect licks and wags for almost twice the time from a smaller dog. But when you think about it, why is this? When giant animals, such as elephants, live as long as people, why does larger size means shorter life for dogs?

Science Thinks It Knows “Why”

The other side of the argument is to ask why smaller mammals, such as mice, lead shorter lives than elephants. The answer is the smaller the mammal, the faster their metabolic rate. Their inner “engine” runs harder and faster, and burns out sooner.

Think of this as having a finite amount of energy programmed into the body, and a small animal uses their quotient up faster. However — and this is where it becomes relevant — this doesn’t hold true for dogs.

When you compare the metabolic rate of small dogs with large, then teacup-sized individuals have a relatively slower metabolic rate than you’d predict for their size and are relatively energy-efficient.

But this doesn’t tell us why big dogs lead shorter lives.

An antioxidant-rich diet may give your giant dog a longevity boost. By: Dallas Krentzel

Why Do Big Dogs Die Younger?

A research study at Colgate University looked into this question. After taking tissue samples from a variety of different-sized dogs — both puppies and old timers — the research team grew cells from the samples in the lab and analyzed them to look for significant differences. And they found one.

Long story short: Large-breed puppies have a revved-up metabolism in early life. In other words, they’re driving their “engine” hard (just like those short-lived mice). Indeed, they rev things so hard that those developing cells are overwhelmed with free radicals. These free radicals cause what’s called “oxidative damage.”

Oxidation is the same process that causes metal to rust — think of this happening inside cells, and you see the problem. That early push for growth sets up long-term cellular damage that programs in a shortened lifespan.

It’s a chicken-and-egg situation. Large-breed puppies have a phenomenal amount of growing to do and need rapidly metabolizing cells to do it. Those hyperactive cells produce more waste products than the body can get rid of, which lights a fuse for self-destruction in the long term.

Ways to Help Your Dog Live Longer

The obvious answer is, from a young age, feed a diet rich in antioxidants. A bit like opening the garage door to let those toxic engine fumes out, antioxidants break down free radicals and take away their sting.

This is a new field of research, so feeding antioxidants isn’t yet backed up by science as a way to extend your giant dog’s life, but heck — what harm can it do?

This big bullmastiff needs a little help from Dad:

Vitamin E, the hero of antioxidants, can be found in fish oils (those wholesome omega-3 oils), green leafy vegetables, wheat germ, blueberries, cranberries and blackberries, among other things. Obviously, a balanced diet is essential for healthy growing bones, so if you supplement your pup, get the advice of a veterinary nutritionist first.

Other ways to keep a giant dog around for longer include:

  • Screening parents: Many large dog breeds are associated with hereditary health disorders. Always source a puppy from responsible breeders who have screened the parent dogs.
  • Knowing your breed’s problems: Familiarize yourself with the health problems linked to your dog’s breed and be proactive. For example, a big issue with Dobermans is dilated cardiomyopathy. But yearly heart screening can identify dogs who would benefit from medication that can extend life by months or years.
  • Feeding age-related diets: From a growing puppy to a senior dog, feed a diet designed for both their size and age to nurture healthy organ function.
  • Taking preventative care: Prevent avoidable problems with regular vaccination or parasite control.
  • Feeding nutraceuticals: Consider food supplements to boost the immune system, encourage joint repair and have an antioxidant action.

Also, watch their weight — a lean waistline means a longer life. Studies comparing litters of puppies showed those who were slim in the first year of life lived 2–3 years longer than their chubbier counterparts.

So there we have it. There’s no miracle answer for extending the life of your giant dog, but you can definitely make a difference in their quality of life.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed April 28, 2017.

Dr. Pippa Elliott, BVMS, MRCVS

View posts by Dr. Pippa Elliott, BVMS, MRCVS
Dr. Pippa Elliott, BVMS, MRCVS, is a veterinarian with nearly 30 years of experience in companion animal practice. Dr. Elliott earned her Bachelor of Veterinary Medicine and Surgery from the University of Glasgow. She was also designated a Member of the Royal College of Veterinary Surgeons. Married with 2 grown-up kids, Dr. Elliott has a naughty puggle called Poggle, 3 cats and a bearded dragon.

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