Small dogs with long noses, such as whippets and miniature dachshunds, live for years longer than large flat-faced breeds such as English bulldogs, new research said on Thursday.

The study, which is based on data from more than half a million dogs across the UK, aims to help people planning to get a dog ensure they choose a breed that will have a long and healthy life.

Lead author Kirsten McMillan, data manager at UK charity Dogs Trust, said it was the first study to look at how life expectancy varies across such a broad range of factors, including breed, size, face shape and gender.

"A medium-sized, flat-face male like an English bulldog is nearly three times more likely to live a shorter life than a small-sized, long-faced female, like a miniature dachshund or an Italian greyhound," she told AFP.

Out of more than 150 breeds and crossbreeds across the UK, the median life expectancy for all dogs was 12.5 years.

But for French bulldogs -- ranked the most popular breed in the United States last year by the American Kennel Club -- the number was just 9.8 years.

Previous research has suggested that the short noses of flat-faced -- also called brachycephalic -- dogs allow them to more closely resemble human babies, rendering them particularly cute to their owners.

But those short noses also cause significant breathing problems.

Dan O'Neill, chair of the campaign organisation Brachycephalic Working Group, said the study further highlighted the "health and welfare crisis" suffered by these hugely popular breeds.

"It is crucial that the public prioritises health over what they might think looks 'cute' and we urge anyone considering getting a flat-faced breed to stop and think," he said.

- Designer breeds? -

The study, published in the journal Scientific Reports, found that the dogs with the longest life expectancy are Lancashire heelers with a median of 15.4 years, followed by Tibetan spaniels (15.2 years) and miniature dachshunds (14 years).

Labradors, the most popular breed in the UK, scored 13.1 years.

Female dogs tended to live a little longer than males, with a life expectancy of 12.7 years compared to 12.4.

The study also found that pure breeds lived a little longer than crossbreeds –- the opposite finding of previous research.

This was probably due to the dawning of the "era of the designer breed", with deliberate crossbreeds such as labradoodles, cockapoos and pomskies becoming increasingly fashionable, McMillan said.

"We're no longer just talking about mutts or unknown mixes versus purebred dogs," she said.

For those considering buying or adopting a dog, it is important to be aware that some breeds will need more trips to the vet, McMillan emphasised.

But vet bills aside, a bigger consideration is the love and affection potential owners will invest in their hairy companions.

"These animals are members of our family," McMillan said.

"We want to ensure that we're doing everything we can to provide them with a long, happy and healthy life."