Dog years are a myth and puppies are middle-aged, scientists claim

The idea that dogs age seven years for every one human year is wrong, scientists have claimed.

Researchers at the University of California say they have found puppies are middle-aged by the time they are two, with dogs tending to then age more slowly in later life.

By the time they get to three, dogs are roughly equivalent to a 50-year-old human, according to the study.

The researchers looked at exactly how dogs age by focusing on the DNA methylation in 104 labradors aged between four weeks and 16 years old.

The DNA changes over time as cells mature, allowing scientists to track an animal’s biological progression.

After assessing the results, the researchers then compared their findings to those from 300 humans.

By the age of two, the labrador DNA was equivalent to a human in their early forties, rather than a 14-year-old human, which the traditional formula would suggest.

However, ageing slows in dogs over time, meaning that by the age of 10, a labrador is similar to a person aged 68.

This ties in with the long-held formula for calculating the age of dogs, which was developed on the assumption that most canines lived until around 10, while humans lived until around 70.

“The expected lifespan of labrador retrievers, 12 years, correctly translated to the worldwide lifetime expectancy of humans, 70 years,” the researchers said.