Dogs can act as powerful social catalysts, making it easier for people to make friends with each other, researchers say.

No matter what the location, or the breed of dog, the impact is the same.

Researchers from Warwick University, writing in the British Journal of Psychology, said that dogs gave people a safe topic of conversation with which to break the ice with a stranger.

To test their theory they monitored the daily outdoor routines of two people, one was alone and the other was accompanied by a dog trained to ignore passers-by so it would initiate social contact.

The people who took part were sometimes smartly dressed and at other times scruffy.

Being in the company of a dog increased all social interactions, no matter what the appearance of the dog or handler.

Researcher Dr June McNicholas said: "This may help us understand why pet owners are frequently reported to be healthier than non-owners.

"It may be that increased casual social contact can increase feelings of well-being, provide companionship and a sense of social integration."

A spokeswoman for the Royal Society for the Prevention of Cruelty to Animals said a close bond between a dog and its owner could have benefits for both parties.

But she added: "We would not encourage people to take on a dog purely for social reasons.

"People who take on a dog should do it for the right reasons and must be able to provide the care and commitment involved in looking after an animal properly."