JACK RUSSELLS have the longest life expectancy of pet dogs in the UK, while French Bulldogs have the shortest, a new study suggests.According to the research, Border Collies had the second-longest life expectancy at 12.1 years, with Springer Spaniels third on 11.92 years.

Dr Elinor Karlsson of the University of Massachusetts Umass Chan medical school, a co-author of the study, said research revealed a huge diversity of behaviours within each breed.“Even if the average is different, you’ve still got a really good chance of getting a dog that doesn’t match what people say that breed is supposed to be,” she said.