A picture of a man who stripped down to his underwear and crawled across a frozen river to rescue his trapped dog has emerged. But why do people risk their lives to save dogs?

The tale of dog owners taking extraordinary risks to save their furry friends from freezing or fast flowing water is a familiar story.

But the dangers of owners falling into distress after desperate rescue attempts are equally well documented.

"Woman and dog pulled from river", "Owner tried to save dog from sea", "Man dies after dog rescue attempt off Brighton beach" are headlines from the last couple of years alone.

And according to the Royal Society for the Prevention of Accidents (Rospa), on average there are seven animal rescue-related deaths in the UK a year.

Animals are actually more resilient than humans believe - they can deal with cold for longer than humans, and in most of the cases when people have gone in to rescue a dog, it has got out safely a few minutes later, the charity says.

So why do people put themselves in harm's way for their pets?

The RSPCA's Andy Robbins says for a lot people a pet is part of the family - so if they see it in distress, or fear for its safety, they want to do all they can to help.

There is an emotional tie which means people react without thinking of the consequences, he says.

As well as seeing pets as part of the family, Dr Roger Mugford, an animal psychologist who runs the Animal Behaviour Centre, says owners often anthropomorphise their animals, particularly if they are dogs.

It is understandable, Mugford argues, because social animals like dogs also extend their emotions to us - and often show similar reactions in emergencies.

Image caption Essex Fire Service says the man's actions were extremely dangerous

"You hear tales of dogs waking owners when fire alarms go off, stopping them from crossing a road at a dangerous point, jumping into rivers when their owners fall in.

"We tend to believe a dog is on our side - it is a powerful emotive reason for keeping dogs, and why we love them," he says.

Mugford also argues that humans have a strong caring, altruistic nature - while animals have a perceived vulnerability - which adds to the impulse to help.

But he says dogs benefit from stronger senses - like smell and acute hearing - and can pick up on danger that is sometimes not apparent to humans.

Laura Quickfall, from the Kennel Club, agrees that dogs are perhaps more intelligent and capable animals than people think.

"It may be that they are able to cope in situations like this better than humans.

"Unfortunately we have heard of cases where the owner has died trying to save their dog and their dog has managed to rescue themselves," she says.

In my case, I caught pneumonia and my dog had a great time Dr Roger Mugford, Animal psychologist

Quickfall says responsible dog owners should always look out for the health and welfare of their dog, but not to the detriment of their own safety.

"We do hear of people putting themselves in dangerous situations to save them but we would never recommend this. In this situation we would recommend that any dog owner calls for professional help, such as the fire service," she says.

But she says the fact that this type of behaviour is not unusual is testament to the bond between dogs and their owners.

Rospa's David Walker says there are hundreds of calls to emergency services every year concerning animals which get stuck in ice, rivers, mud and weirs.

But it is usually only when owners try to rescue them themselves that problems escalate, he says.

He says the best solution is prevention - and advises owners to keep pets on leads near icy river banks and ponds.

If a pet does fall into difficulty, he says throwing something to try and rescue the animal from the safety of the bank is the best option. But if that fails, the next step should always be the fire and rescue services.

For Mugford, who has crawled across ice to save a dog once himself, fighting the emotional impulse to act will always be a struggle.

"If you look around, there are so many examples of people putting themselves in harm's way to save their pet. In my case, I caught pneumonia and my dog had a great time," he says.