Study also finds the decline is more limited.

A new study has shown that larger dogs start to exhibit signs of behavioural and cognitive decline earlier than smaller dogs.

However, the level of cognitive decline is often less severe, with larger dogs less likely to have canine cognitive dysfunction.

The study of 15,000 dogs found that dogs weighing more than 30kg showed an earlier onset of age-related decline by two to three years.

However, although smaller dogs lived for longer before the onset of cognitive decline, dogs weighing less than 7kg were four times more likely to show signs of cognitive decline in old age compared to larger dogs.

The researchers also discovered purebreds and long-nosed dogs, such as greyhounds, have a higher risk of developing cognitive decline when old compared to other dogs.

Although it is well-known that larger breeds tend to have shorter lifespans, the researchers from Eötvös Loránd University, Hungary, wanted to investigate at what age cognitive and behaviour changes start and how fast they progress for dogs of different sizes, head shapes, and purebred status.

Dr Turcsán, first author of the study, said: “For those who want a smaller sized dog but do not want to risk severe mental health problems in old age or want a larger sized dog but do not want to risk physical health problems at 7-8 years of age, we recommend a dog from the 10-30kg size range.

“Based on our results, these dogs have a longer healthspan relative to their expected lifespan than their smaller and larger counterparts.”

The study, ‘Differential behavioral aging trajectories according to body size, expected lifespan, and head shape in dogs’, has been published in the journal GeroScience.

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