great dane smelling tiny chihuahua
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Why do small dogs live longer than large dogs?

By Justine Seraphin Country Manager

Updated on the

In the canine world, a small dog is likely to live much longer than a large dog. While research is still being conducted on the subject, there are some answers as to why this is.

In the animal kingdom, larger species of animals such as elephants live significantly longer than smaller species of animals, like mice. So why then, do small dogs live longer than big dogs?

Well, within the same species, the trend can be reversed. For example, a tiny Chihuahua can live 12 to 20 years while a Great Dane may only live 8 to 10 years. 

Why do small dogs live longer than big dogs?

While not everything is understood about the subject, there are some things we know affect the reduced lifespan of large dogs.


The quick answer to the question “Why do small dogs live longer than big dogs?” is simply that big dogs age faster. According to research, when dogs of any breed reach one year old, that equates to about 15 human years. When they reach two years old, that equates to about 25 human years. After that point, ageing starts to change dramatically between breeds, with larger breeds ageing much faster than smaller ones. A 9-year-old Great Dane is about 86 years old in human years, while a 9-year-old Chihuahua is only around 50 years old in human years. 

This, of course, means that large dogs can succumb to age-related illnesses, or simply to old age much sooner than smaller dogs. The question as to why large dogs age faster is still being explored by scientists today.


Not only do large dogs age faster than small dogs, but their size also increases health problems. Indeed, a Chihuahua and a Great Dane may take approximately the same amount of time to reach their adult size, but the Great Dane has a lot more growing to do in that time than the Chihuahua. This accelerated growing process means they may experience abnormal cell growth which could be linked to cancer. Many large breeds of dog are indeed well-known for developing cancers (e.g. Rottweilers, Bernese Mountain Dogs, and Boxers to name a few).

Additionally, large dogs tend to put more strain on their bodies than small dogs, so they ‘wear out’ more quickly. Many large breeds of dog suffer from joint problems, for example, and may succumb to hip dysplasia

What factors affect how long dogs live?

Apart from size, there are many other factors which can affect a dog’s lifespan. Scientifically speaking, three main points stand out:

  • Breeding: A dog bred from a smaller gene pool is more likely to succumb to genetically transmitted diseases than dogs bred from larger gene pools. That’s why mix-breeds or cross-breeds live longer than purebreds, on average. This is also why rarer breeds of dogs tend to be healthier than very popular breeds, where unscrupulous breeders are often involved.
  • Dental health: Going to annual dental cleanings can reduce your dog’s risk of death by up to 20%!
  • Weight: Overweight and obese dogs are more likely to suffer from joint disease, breathing issues, and some cancers than dogs at an ideal weight. That’s why it’s so important to feed your dog a healthy diet and to exercise them according to their needs.

Of course, so many other factors contribute to your dog’s life expectancy. Dogs need mental stimulation, regular heartworm, tick, and flea medication, regular grooming, and of course, lots of love and companionship.

How much longer do small dogs live than big dogs?

There’s no exact answer to this question. However, as a general rule of thumb, it’s thought that the average lifespan for very large dogs is around 7 years, while the lifespan for small dogs is around 14 years. So, on average, small dogs tend to live 7 years longer than their larger counterparts.

What dog breed lives the longest?

Yorkshire Terriers, Chihuahuas, Dachshunds, Toy Poodles, and Lhasa Apsos are currently top of the charts when it comes to longest lifespans. 

The oldest dog in history was Bluey, an Australian Cattle Dog who lived to be 29 years old!

Whatever breed you own, one thing is the same for everyone: We know our dogs sadly won’t live as long as we will. So enjoy every moment with your beloved furbabies.

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