For people in the UK, 31 is the average age at which they get married for the first time, women give birth, and, in some regions, buy their first home – but for dogs it is equivalent to being about 200 years old.

This is why the news that Bobi, a Portuguese mastiff, the oldest known dog in the world, had died aged 31 on 21 October has generated so much global interest – as well as a bit of scepticism.

Danny Chambers, a vet and council member of the Royal College of Veterinary Surgeons, said he thought any vet would be sceptical about Bobi’s age.

“You can never be 100% certain, but if a human said they were over 200 years old you’d definitely be sceptical,” he said. (Bobi’s owner has been contacted for comment.)

A veterinary professor of animal welfare, Andrew Knight, said it was plausible that among the hundreds of millions of dogs around the world (kept dogs alone are estimated at 470 million), there will be “a few with very good genes”.

But doubts aside, there are ways to help your dog lead a long and healthy life. Bobi could have benefited from the owners’ decision not to keep him on a lead. “His lifestyle seems to have provided plenty of opportunity to exercise and explore his peaceful farm and forested surroundings without restriction, helping Bobi to stay physically and mentally well,” said Knight.

Bobi was said to have been fed human food soaked in water to remove seasoning, a detail that has stoked controversy in the veterinary community and has been upheld as a shining example by raw feeding advocates.

Knight said it was possible for dogs to survive on a diet of human food scraps, since this is “consistent with canine evolutionary history”. However, in order to live a long life, they needed owners who followed “an unusually healthy diet”.

“Most dogs would not do as well, unless fed a diet created by reputable pet food manufacturers to include all of the nutrients dogs need,” he said.

The secrets of pet longevity, according to the vets, include nutritionally sound diets and plenty of exercise.

“Keep your dog a healthy weight – just like humans, overweight dogs are at greater risk of diabetes, arthritis, heart disease, cancer, and many other conditions. Although there are other options, a high-quality diet from a good brand in the from of kibble is the best bet for most dogs and easiest for owners,” said Chambers.

Knight said there was some evidence to suggest that nutritionally sound vegan diets could result in greater longevity: a 2022 study of more than 1,000 dogs showed those fed vegan diets lived 1.5 years longer – about an extra decade, in human terms.

Love, attention, socialisation and behaviour training in puppyhood were also important, he added.

The vets agreed that regular checkups for vaccinations, parasite control and tooth cleaning were all important, too. “Make sure your dog has their teeth scaled and polished when necessary to remove harmful bacteria that not only cause their teeth to rot and their breath to stink, but can cause infections of the heart and kidneys in older dogs,” advised Chambers.

But good genes also count: some breeds will live longer than others. Giant breeds such as great danes are unlikely to live past seven years old, and breeds such as flat-coated retrievers have a higher risk of cancer, whereas smaller dogs, especially terrier crosses, should live much longer.

Owners should not fixate on keeping their pets alive for as long as possible, said Chambers. “Dogs don’t actually have any ambition to live a long life. They want to be happy day by day, and as vets we see a lot of suffering because owners want to keep their pets alive longer, despite them being unhealthy and in pain. People shouldn’t feel guilty putting an older animal to sleep as this can often be the kindest option.”