It has been used to calculate a dog's age in comparison to a human's for decades - but new research has disproved it entirely.
Researchers from the University of California San Diego’s School of Medicine claim rather than one "human year" being equivalent to seven " dog years", it's closer to 30.
Writing in the journal Cell System, the team explain how they developed a more accurate formula to calculate a dog's age based on the chemical changes in the DNA as organisms grow old.
