Longevity of companion dog breeds: those at risk from early death.

McMillan, K. M., Bielby, J., Williams, C. L., Upjohn, M. M., Casey, R. A., & Christley, R. M. (2024). Longevity of companion dog breeds: those at risk from early death. Scientific Reports, 14, 531. https://doi.org/10.1038/s41598-023-50458-w

What Was This Dog Longevity Study Trying to Find Out?

Dogs vary enormously in size, body shape, behavior, and inherited traits. Their lifespans vary considerably as well. The researchers behind this study wanted to examine those differences across a much larger population than is available in most breed-specific longevity studies.

The analysis looked at survival according to breed, body size, sex, skull shape, and whether dogs were recorded as purebred or crossbred. Researchers also examined whether breeds that share evolutionary ancestry tend to have similar longevity patterns.

The paper places those questions within a broader discussion of inherited health and breed structure. It notes that hundreds of inherited disorders and traits have been described in dogs, including hip dysplasia, brachycephalic obstructive airway syndrome, cardiomyopathies, endocrine dysfunctions, and blood disorders. The authors also discuss conformation-related health problems such as orthopedic disorders, skin disease, ear disease, eye disease, and breathing difficulties as part of the wider welfare context surrounding selective breeding. These conditions were not measured as causes of death in this study, but they help explain why breed longevity is biologically important to investigate.

How Large Was the Dog Lifespan Study?

The final dataset contained 584,734 dogs living in the United Kingdom. Of those dogs, 284,734 had died by the time the data were analyzed.

Records came from 18 organizations rather than one veterinary network or registry. Breed registries contributed 45.0% of the data, veterinary corporations 26.5%, pet insurance companies 17.1%, animal welfare charities 5.9%, and academic institutions 5.5%.

The dataset included 473,423 purebred dogs and 111,311 crossbred dogs. Researchers had enough information to calculate survival estimates for 155 recognized purebred breed groups. Dogs ranged from puppies to individuals as old as 24 years.

Why Were Dogs That Were Still Alive Included?

A survival study does not need to wait for every dog in the dataset to die.

About 300,000 dogs were still alive when the study ended. Their information could still contribute because the researchers used statistical methods designed for censored data.

A censored observation means that a dog’s survival is known up to a certain age, but its eventual lifespan is not yet known. A 12-year-old dog that is alive when the dataset closes provides evidence of survival through age 12 even though the dog’s final age at death remains unknown.

The researchers used Kaplan-Meier survival analysis, which incorporates information from both deceased dogs and dogs whose lifespans were still ongoing. Treating a living dog’s current age as its final lifespan would bias the analysis.

What Does Median Survival Mean in This Study?

The paper primarily reports median survival rather than mean, or arithmetic average, lifespan.

Median survival is the age at which the estimated survival curve reaches 50%. Half of the studied population is estimated to survive beyond that point, while half does not.

The researchers chose median estimates because dog longevity data are not normally distributed. A small number of exceptionally old dogs can pull an arithmetic mean upward and make it less representative of the broader population.

Across all 584,734 dogs in the dataset, median survival was estimated at 12.5 years. Purebred dogs had a median survival of 12.7 years, while the broad crossbred group had a median survival of 12.0 years.

This is one reason lifespan figures from this study may differ from the “average lifespan” ranges commonly listed on breed websites. Different sources may use different populations and different ways of calculating longevity.

How Should These Median Survival Numbers Be Read?

The median survival figures are best understood as population-level midpoints, not as predictions of how long an individual dog will live. If a breed had a median survival of 13 years, that means the estimated survival curve reached 50% at about age 13: roughly half of the dogs were estimated to survive beyond that age and half were not.

The number does not mean that most dogs died at 13 or that 13 years is a typical maximum lifespan. It shows where the middle of the breed’s survival pattern fell in this particular UK population, making it useful for comparing groups without letting a small number of exceptionally old dogs distort the result.

How Much Did Lifespan Differ Between Dog Breeds?

Breed was strongly associated with survival.

Among the analyzed breeds, the Caucasian Shepherd Dog had the lowest estimated median survival at 5.4 years. Other breeds toward the lower end included the Presa Canario at 7.7 years, Cane Corso at 8.1 years, Mastiff at 9.0 years, Saint Bernard at 9.3 years, and both the Bulldog and French Bulldog at 9.8 years.

At the other end, the Lancashire Heeler had an estimated median survival of 15.4 years. The Tibetan Spaniel reached 15.2 years, Shiba Inu 14.6 years, Papillon 14.5 years, Border Terrier 14.2 years, and Miniature Dachshund 14.0 years.

The study’s survival curves also show why a single breed number only tells part of the story. For example, Figure 3 compares Border Collies, Border Terriers, Bulldogs, French Bulldogs, Labrador Retrievers, Mastiffs, Miniature Dachshunds, Pugs, and crossbred dogs across age. The curves show how survival probability changes gradually rather than ending at one fixed lifespan.

How Did Body Size Relate to Dog Lifespan?

Body size showed a clear relationship with survival.

Small purebred dogs had an estimated median survival of 12.7 years, compared with 12.5 years for medium breeds and 11.9 years for large breeds. Overall, larger dogs tended to have shorter survival than smaller dogs.

The study identified this population pattern but did not establish one biological mechanism responsible for it. Body size can reflect differences in growth, skeletal development, metabolism, inherited disease risk, and breed history, all of which can overlap.

Did Female Dogs Live Longer Than Male Dogs?

Females showed a modest survival advantage.

Across purebred and crossbred dogs together, females had an estimated median survival of 12.7 years compared with 12.4 years for males.

The same pattern appeared when purebred and crossbred dogs were considered separately. Purebred females had a median survival of 12.8 years compared with 12.5 years for purebred males. Crossbred females reached 12.3 years compared with 11.9 years for crossbred males.

The study was designed to identify survival differences rather than determine which hormonal, reproductive, medical, environmental, or behavioral factors produced them.

How Did Skull Shape Relate to Dog Lifespan?

The researchers grouped purebred dogs according to cephalic index, a measurement describing the relationship between skull width and skull length.

Brachycephalic dogs have relatively shortened skulls and flatter faces. Mesocephalic dogs have more moderate skull proportions, while dolichocephalic dogs have relatively long, narrow skulls.

Mesocephalic breeds had the highest median survival of the three groups at 12.8 years. Dolichocephalic breeds had a median survival of 12.1 years, while brachycephalic breeds had the lowest at 11.2 years.

Body size and sex changed those patterns further. Medium-sized brachycephalic males had an estimated median survival of 9.1 years and females 9.6 years, while small dolichocephalic males and females both reached 13.3 years.

The paper discusses brachycephalic obstructive airway syndrome and breathing difficulties within the broader health and welfare concerns associated with extreme conformation. It also references eye, skin, ear, and orthopedic problems associated with selective breeding and exaggerated physical traits. Those diagnoses were not tested as explanations for mortality in this dataset.

Did Purebred or Crossbred Dogs Live Longer?

In this study, purebred dogs as a group had an estimated median survival of 12.7 years, compared with 12.0 years for crossbred dogs. That does not mean every purebred breed lived longer than crossbred dogs.

The researchers compared each of the 155 purebred breed groups with the crossbred population. About 47% of the purebred breeds had significantly longer survival than crossbreds, about 26% had shorter survival, and the remaining 27% did not differ significantly. In other words, the relationship depended heavily on which breed was being compared.

The crossbred category also combined dogs with very different ancestry. A first-generation cross between two known breeds and a dog with ancestry from several breeds could both be counted simply as “crossbred.” The researchers did not have enough ancestry information to distinguish those dogs by their degree of genetic diversity.

That limitation matters because the study could not determine whether genetic effects such as hybrid vigor contributed to longevity in particular crosses. The authors therefore cautioned against interpreting the overall 12.7-versus-12.0-year comparison as proof that purebred dogs are inherently longer-lived than crossbred dogs.

What Did Evolutionary History Have to Do With Dog Lifespan?

One of the more distinctive parts of the study examined lifespan across the evolutionary family tree of dog breeds.

The researchers calculated Pagel’s lambda, a statistical measurement used to determine whether closely related groups tend to resemble one another for a particular trait. Median lifespan produced a value of 0.808, indicating a strong phylogenetic signal.

Closely related breeds therefore tended to have more similar median lifespans than would be expected if longevity were randomly distributed across the breed family tree.

Figure 6 focuses on breeds in the lowest quarter of the longevity distribution. Shorter median lifespans clustered in several related groups, including one containing Mastiffs and Bulldogs and another containing the Presa Canario, Neapolitan Mastiff, and Cane Corso.

The analysis identifies an association between evolutionary history and lifespan. It does not identify a single longevity gene or show that ancestry alone causes earlier death.

What Can Hazard Ratios Tell About Early Death?

The paper frequently reports hazard ratios, abbreviated HR.

A hazard ratio compares the rate at which an event occurs over time between groups. In this study, that event was death.

A value above 1 indicates a faster rate of death relative to the comparison group, while a value below 1 indicates a slower rate. Hazard ratios describe population differences over time and should not be interpreted as the probability that an individual dog will die at a specific age.

The researchers used hazard ratios alongside median survival estimates and Kaplan-Meier survival curves because each measurement describes a different part of the longevity pattern.

What Are the Most Important Limitations of This Dog Lifespan Study?

The size of the dataset is a major strength, but the authors identify several limitations.

The dogs were all from the United Kingdom. Breed populations can differ between countries because of breeding practices, registry policies, imported bloodlines, environment, veterinary care, and population management. The researchers explicitly state that these findings represent the UK canine population and should not be used to make direct assessments of populations in other countries.

The dataset also did not contain cause of death. A dog may have died naturally, been euthanized because of disease or behavior, experienced trauma, or died for another reason. The researchers could identify populations with earlier mortality but could not determine the direct cause of those differences.

That limitation is especially important when considering conditions such as cancer, cardiomyopathy, hip dysplasia, endocrine disease, or respiratory disease. The paper discusses inherited and conformation-related disorders as part of the wider breed-health context, but it cannot determine whether any particular disease caused the survival differences found here.

Neuter status was also excluded because the available records were not considered reliable enough for analysis.

Different sources can introduce different forms of bias. Older dogs may be less likely to have insurance. Breed registries naturally contain more purebred dogs. Veterinary databases may overrepresent dogs receiving more extensive medical care, while welfare organizations contain larger proportions of crossbred dogs. Rapid increases in breed popularity can also create unusually young populations within a dataset.

Median Survival of Selected Common Dog Breeds in the Study

The complete study contains survival estimates for 155 purebred breed groups. This smaller table highlights familiar breeds across the longevity range. These figures are median survival estimates from the UK population analyzed in the study and should not be interpreted as predicted lifespans for individual dogs.

What Does This Study Tell Dog Parents?

The study provides a large population-level picture of canine survival within the United Kingdom.

Breed, body size, sex, skull shape, and evolutionary lineage were all associated with survival patterns. These characteristics also overlap, so no single measurement explains how long an individual dog will live.

The study is particularly useful for identifying populations that may warrant closer investigation. A breed with comparatively early mortality can be examined more closely for inherited disease, conformation, breeding history, environmental influences, or other factors that were outside the scope of this dataset.

For an individual dog, the findings describe probabilities observed across populations. They cannot predict the lifespan of one Labrador Retriever, French Bulldog, Great Dane, Bernese Mountain Dog, Australian Cattle Dog, mixed-breed dog, or any other individual.

The scale of the dataset makes broad patterns visible that would be difficult to recognize within one veterinary practice or one breed community. Those patterns provide a starting point for more focused work on the biological and population-level factors associated with healthy aging and early mortality.

Which Dog Breeds Were Included in the Study?

The survival analysis included 155 recognized purebred breed groups, along with crossbred dogs as a separate comparison group. The researchers required sufficient numbers of both living and deceased dogs for a group to be included in the survival analysis.