Scientists change how we calculate dog years

For decades, dog lovers have been incorrectly calculating the age of their pet pooches. People have traditionally worked out their dog's age in "human years" by multiplying by seven. However, researchers at the University of California San Diego School of Medicine in the USA have come up with a new formula. They say it more precisely determines canine age. Their new method requires a little more than simple mental arithmetic to work out a dog's age. It involves a comparison of the genomes of dogs and humans. Scientists had to analyse how DNA changes as humans and dogs age. The scientists regard such DNA analysis as the best way to measure the ageing speed of mammals.

The researchers analysed blood samples from 105 Labrador retrievers. After a bit of number crunching, they created a graph to show the different rates at which canines and humans age. They said a one-year-old dog is similar to a 30-year-old human, while a four-year-old hound is comparable to a 52-year-old person. Researcher Trey Ideker said by the time a dog reaches seven years old, its ageing slows. He said: "This makes sense. When you think about it, a nine-month-old dog can have puppies, so we already knew that the 1:7 ratio wasn't an accurate measure of age." The researchers said their new formula doesn't fully address the fact that different breeds of dog age at different speeds.