While we all adopt a pup with the understanding that they are going to have far shorter lives than our own, have you ever wondered to yourself, what the longest living dog breeds are? The average lifespan of a dog is 10-13 years, but certain dogs have the potential to outlive others within their breed and the breeds who fall into the general statistic above. To the surprise of most, this is especially true for smaller dog breeds!
In general, we are accustomed to seeing smaller animals live far shorter lives than larger ones, so why is this the other way around for different breed of dogs? If you’re interested in learning more about why small dogs challenge this rule take a look at the guide below. You will find out which dog breeds outlive them all, and take a detailed look at the science behind it.
Why Do Smaller Animals Tend to Have Shorter Lifespans?
According to Kleiber’s law, proposed by Swiss biologist Max Kleiber in the 1930s, smaller mammal species essentially live faster than larger ones. This is due to the fact that smaller animals:
- Have smaller hearts that must pump faster, meaning that they wear down faster than the hearts of larger animals.
- Find it difficult to keep warm, requiring them to produce more energy per square inch of their body weight.
- Have a higher metabolic rate than larger animals, which can impact how quickly their body begins to take damage.
As a result, we see that larger animals outlive their smaller counterparts. But this rule doesn’t seem to apply to smaller dog breeds. If the general rule applies to a greater portion of the animal kingdom, why does it not work with dogs?
Why Does the Opposite Apply to Dogs?
If you are a canine lover, chances are that you have either had a small dog or have had a friend or family member with a small dog, and have noticed that they are among the longest living dog breeds. To understand why, simply take a look at the chart below, and you will see that dogs over 90 pounds tend to reach 17 years of age and dogs under 20 pounds reach up to 28 years of age (blue line).
Again, this is a statistic that will not always apply to all animals; your oversized Irish Wolfhound might very well live to be 15 years or older. The fascinating bit here being that the size rule between mammalian species does not hold true for different breeds of dogs.
The difference in lifespans related to size is statistically significant enough to warrant separating lifespan by weight, but why might this occur within a species?
Ancestry and Breeding
While it would be nice and neat for domesticated dogs to have originated from one wolf species, this is not the case. In 2010, the Annual Review of Genetics published a paper about recent findings in dog genetics. In the paper, it was stated that there is a great deal of variety in the dog genome. Scientists do not know exactly how this happened, but it is likely to have occurred through migration and the reintroduction of domesticated dogs to wild populations.
As far as scientists can tell, the friendliest wild dogs or wolves did the best living alongside human colonies. Naturally, friendly wild dogs that lived around humans tended to breed with one another. Making themselves better human companions by providing certain advantages for humans.
From here, dogs were bred to select for various traits, with size sometimes being a key factor. Something to note is that most dog breeds were created in the last 300 years. While dogs are thought to have been domesticated for somewhere around 40,000 years.
Many small dog breed types have a certain version of a growth hormone called insulin-like growth factor 1 (IGF1). The variant originated somewhere in Persia long ago.
Growth is stunted in most small dog breeds because this growth factor is inhibited. Amazingly enough, instead of being unhealthy runts, these animals tend to be the longest living dog breeds.
Another group looked at the period of expression of IGH genes in large and small dogs. They found that large dogs tended to express the gene for a longer period of time than smaller breeds.
Putting these two pieces of research together implies that the size of a dog is controlled by the mechanisms that turn on growth factor signaling. That means, for the most part, the length of time that a dog will live is partially dependent on the mechanisms in charge of its growth.
So, Which Dog Breeds Live the Longest?
Back to the initial question, the Chihuahua lives, on average, around 18 human years. Many Chihuahuas live well beyond 20 years. Other breeds that follow closely behind include the:
- Shetland Sheepdog
- Yorkshire Terrier
- Shih Tzu
- Lhasa Apso
In case you were curious, the oldest dog that ever lived reached the ripe old age of 29 years and 5 months. Bluey was the name of the Australian Cattle Dog. Bluey lived out his years on a farm in Australia and holds the current world record for the oldest dog.
Want One of the Longest Living Dog Breeds? Choose a Smaller Breed!
The Chihuahua takes the win for the dog breed that lives the longest, with many other small breeds following closely behind.
While we are not exactly sure why these smaller breeds tend to thrive despite their compact bodies, we do know that the reason behind their longevity has to do with their genetics. Looking further into the differences between breeds could lead to significant scientific discoveries in the future.
Please comment below with some of your favorite dog stories. Tell us about your own family dog who had lived to a great age and what they did during their lives! Do you know any other longest living dog breeds? If so, feel free to share more with us about your own personal experience.