Published in the journal PLOS, University of Washington researchers looked at data from over 25,000 dogs across 238 breeds in the United States.

They found that small dogs had an average lifespan of 13.8 years, while larger dog breeds had an average life expectancy of 10.8 years.

When looking at specific breeds, the difference between life expectancies widens.

Chihuahuas have a lifespan of 17.8 years while one of the largest dog breeds, the Great Dane, have an average life expectancy of 7.8 years.

Researchers believe the reason for the long life expectancy for smaller dog breeds is that they have a slower metabolism than large dogs. This means they burn a lot less energy and produce less waste which can help protect them from disease.

Small pooches are also less likely to be injured and are less likely to be overweight.

They found that infectious diseases, bone diseases, gastrointestinal issues, neurological and endocrine problems and ear/nose/throat issues were more prevalent in large dog breeds.

Smaller dogs were more likely to suffer from respiratory issues, heart problems, eye issues, and liver and pancreas issues.

The authors wrote, "Age in dogs is associated with the risk of many diseases, and canine size is a major factor in that risk. However, the size patterns are complex”.

“While small-size dogs tend to live longer, some diseases are more prevalent among small dogs," the authors said.

"These results provide insights into the disease categories that may contribute to reduced lifespan in larger dogs and suggest multiple further avenues for further exploration.”