The Dogs That Live Longest, by a Nose

There are exceptions to those broad trends, and the findings might not apply to dogs outside Britain, where breeding practices — and gene pools — may be different, the researchers noted.

More research will be needed to determine why some breeds have shorter life spans than others. Some breeds are genetically predisposed to serious health problems, but breed-related differences in behavior, lifestyle, diet, environment or other factors could also play a role in shortening some dogs’ lives, experts said.

“Now that we have identified these populations that are at risk of early death, we can start looking into why that is,” said Kirsten McMillan, an author of the new study and the data manager at Dogs Trust, a dog welfare charity in Britain that led the research. “This provides an opportunity for us to improve the lives of our dogs.”

The study is based on a database of 584,734 British dogs, which the researchers assembled from breed registries, pet insurance companies, veterinary companies and other sources. These types of records, which can be prone to various biases, are not necessarily representative of Britain’s general canine population, the scientists acknowledged.

But Dr. Audrey Ruple, a veterinary epidemiologist at Virginia Tech who was not involved in the new study, said the researchers’ use of so many different data sources was one of the study’s strengths. “I think this is a fantastic approach,” she said.

Most of the dogs were purebred, representing one of 155 breeds; the rest were combined into a single crossbred category. The researchers categorized each breed’s overall body size as small, medium or large and its head shape as flat-faced, medium-proportioned or long-faced.

Across all dogs, the median life span was 12.5 years, the researchers found, but average life span varied “quite spectacularly” among breeds, Dr. McMillan said. Lancashire heelers, a breed of petite herding dogs, were canine Methuselahs, living for 15.4 years on average. The much larger Caucasian shepherd dogs, though, had an average life span of just 5.4 years.