Study Shows Why Smaller Dogs Live Longer

Poodle Dog

Poodle Dog

Scientists may finally understand why small dogs generally outlive larger breeds. Their research indicates that although small and large dogs suffer from a similar number of health conditions, larger breeds tend to experience more severe ailments.

The relationship between size, age, and health in dogs is a complex one, with fascinating implications for both canine and human medicine. The comprehensive study by the Dog Aging Project (DAP) sheds light on how different breeds and sizes of dogs experience various health conditions throughout their lives. This exploration provides valuable insights into the mysteries of aging and disease, not just in our four-legged friends, but potentially in humans as well.

The study, conducted by researchers throughout the United States, analyzed over 25,000 dogs across 238 breeds. The findings, published in the journal PLOS ONE, revealed that larger dogs are more susceptible to cancer, bone-related diseases, gastrointestinal problems, neurological and endocrine conditions, as well as issues with their ears, nose, or throat, and infectious diseases. In contrast, smaller dogs were prone to ocular, cardiac, and respiratory issues, along with liver or pancreatic diseases. Interestingly, a dog’s size did not significantly affect kidney or urinary diseases.


Regardless of size, age remains a universal factor in disease risk. As dogs grow older, they are increasingly likely to develop various health issues. This trend is consistent across all breeds and sizes, although the specific conditions may differ. For example, the likelihood of skin conditions, orthopedic issues, and cancer increases with age in larger dogs, while smaller breeds see a rise in endocrine and cardiac diseases.

The study also considered factors such as the dog’s breed (purebred vs. mixed-breed) and the geographic location of the dog’s residence. These factors, however, didn’t significantly alter the primary relationships between size, age, and disease prevalence.

These results suggest that while larger dogs do not necessarily have more health conditions than smaller ones, they are at a higher risk for certain diseases. This could partly explain their shorter lifespans. This phenomenon is intriguing and somewhat counterintuitive, as in many mammalian species, larger size often correlates with longer life spans. In dogs, however, it appears that size and longevity have an inverse relationship.

However, the researchers emphasize the need for further study to better understand the relationships between a dog’s age, size, and disease prevalence. They clarify that this study does not establish a causal link between dog size, age, and disease. Nonetheless, the insights gained could pave the way for more in-depth research, particularly into how age and size influence specific conditions, potentially shedding light on the reduced longevity of larger dogs.

“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,” the study authors conclude in a media release.

The findings from the Dog Aging Project are not just vital for veterinary science but also offer a window into understanding human health. The similarities in disease patterns and aging between dogs and humans can provide valuable insights for medical research. For example, understanding how size affects longevity and health risks in dogs might shed light on similar patterns in humans.

The project’s vast database and its ongoing nature promise even more insights in the future. As longitudinal data becomes available, it will be possible to explore how specific health conditions progress over time and how they might ultimately impact a dog’s lifespan.

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