As many owners of Great Danes, St. Bernards, Bernese Mountain Dogs and Mastiffs already know, large breed dogs tend not to live as long as their smaller breed cousins. Even so, scientists had yet to determine the reasons for this difference in lifespan—until now.
Researchers at the University of Göttingen in Germany decided to test three theories. One was based on veterinarian recommendations for geriatric checkups. Many vets consider 11-year-old small dogs, 9-year-old medium-sized dogs, and 7-year-old large dogs to be seniors. As such, the scientists hypothesized that the larger dogs naturally age faster. Their second theory was that the larger breeds begin to age earlier. The third was that large dogs are at increased risk of death throughout their lives, regardless of age.
To determine which hypothesis held the most merit, the researchers analyzed the demographic data—including age and cause of death—of more than 50,000 dogs and 74 breeds in the Veterinary Medical Database. Each of the theories produced a different “mortality curve” when risk of death was charted against age.
Upon examination of the graph generated by the actual data, the mortality curve closely resembled that produced by the faster-aging theory. This indicates that large breed dogs indeed age at an accelerated pace.
Future studies will likely address the reason for this rapid aging. One possibility, identified by other researchers, is IGF-1 growth hormone. Smaller breed dogs have a lower concentration of this hormone in their blood than large dogs do. Other studies have found a correlation between higher levels of IGF-1 and increased risk of death from age-related diseases in mammals including humans.
Have you ever owned a large breed dog? How long did he or she live? Share your data in the comments.