Small Dogs Live Longer but Age Faster — How Size Shapes Their Health

Small dogs can live twice as long as large ones, a fact many devoted pet owners already know. A team of researchers from Eötvös Loránd University in Budapest, Hungary, set out to explore whether breed size is linked to how dogs age. The scientists focused on how aging affects dogs’ cognition and physical abilities.

What the Study Revealed

The team analyzed data from 15,000 dogs, looking at age, behavior, and cognitive function. They also assessed each dog’s size, head shape, and breed. The analysis found that, on average, behavioral and cognitive aging in dogs begins around 10.5 years of age. However, the onset and pace of aging depend on body size, the Daily Mail reported.

For dogs weighing over 66 pounds (30 kg), age-related decline begins earlier than in smaller breeds—by about two to three years. Yet these larger dogs show a slower rate of cognitive decline compared with smaller breeds. “Large dogs experience physical deterioration at an earlier age, and the accumulation of diseases and degradation of sensory functions lead to ‘senior behavior’ long before mental decline begins,” said Borbála Turcsa, the study’s lead author.

In contrast, breeds weighing less than 15.4 pounds (7 kg) are four times more likely than larger breeds to experience cognitive decline in their senior years. Another pattern in the data: dogs with long noses (like hunting hounds) face a higher risk of cognitive decline in old age than dogs with shorter snouts (such as pugs and French bulldogs).

The research also found that owners tend to consider their dogs “old” at around six years of age, regardless of size. That perception is 4–5 years earlier than when dogs are actually considered seniors. The researchers say this may be linked to graying fur and subtle physical changes.

Based on their findings, the team recommends choosing dogs that weigh between 22 and 66 pounds (10 to 30 kg), such as Welsh Corgis, Staffordshire Bull Terriers, and Schnauzers. “For those looking for a smaller dog without serious cognitive problems in old age, or a larger dog without physical health problems by age 7–8, we recommend animals weighing between 10 to 30 kg,” Turcsa said.

Overall, the analysis confirmed that body size influences a dog’s lifespan as well as its mental and physical health.