A new University of Sydney trial lends weight to the expression 'man's best friend,' showing a sample of new dog owners saw a significant reduction in loneliness within three months of acquiring their pet.

The PAWS trial is the first long-term Australian controlled study to look at dog ownership and mental wellbeing in the community. Published today in BMC Public Health the trial followed a total of 71 Sydneysiders over an eight-month period.

It compared the mental wellbeing of new dog owners to those who intended to acquire a dog (but held off during the eight-month study period) and those who had no intention of owning a dog.

The researchers from the University's Charles Perkins Centre and RSPCA NSW found new dog owners self-reported lower levels of loneliness within three months of getting a dog, with the effect persisting to the end of the study.

They also found some evidence to suggest new dog owners experience a reduction in negative mood after acquiring a dog, such as being upset or scared. But, they saw no impact on psychological distress, which includes the symptoms associated with depression and anxiety.

With 39 percent of Australian households owning a dog, lead author Ms Lauren Powell said the small trial sheds light on the potential health benefits of dog ownership.

"Some previous research has shown that human to dog interactions can have benefits in settings like nursing homes using therapy dogs, however, there is very little research looking at the impact for everyday dog owners interacting with their dog at home," said Ms Powell, Ph.D. candidate in the Charles Perkins Centre.

"While we can't pinpoint exactly how dog ownership positively affected mood and loneliness in our participants, many people in the study reported that they got to know others in their neighbourhood because of their new dog.

"We also know that short-term interactions with dogs improve mood so it may be that the regular occurrence of these interactions taking place with dog ownership produced long-term improvements."

The study design also allowed researchers to minimise the possibility that people who are thinking about getting a dog may already be experiencing better mental wellbeing.

Senior author Professor Emmanuel Stamatakis from the Faculty of Medicine and Health said in today's busy world many people have lost a sense of community and social isolation is increasing.

"If dogs can help people get out into their neighbourhoods more and to meet other people, this is a win-win," said Stamatakis, Professor of Physical Activity, Lifestyle, and Population Health in the School of Public Health.

"This is particularly important in older age when there is an increased risk of isolation and loneliness. It's a major cardiovascular disease risk factor, it's a major cancer risk factor, and it's a major risk factor for depression."

The researchers acknowledge that the findings contrast with earlier international studies and further larger-scale trials are needed to examine the intricacies of the relationship between dog ownership and human mental health.

"This is a new and emerging area of research, particularly given everyone's relationship with their dog is so different."

"Finding a way to assess that and take that into account is half the challenge."

The group is also currently conducting parallel studies looking at the impact of dog ownership on the physical activity patterns of their owners.

In collaboration with the RSPCA NSW, the Dog Ownership and Human Health Research Node at the Charles Perkins Centre brings together experts in public health, physical activity and exercise, disease prevention, behaviour change, health psychology, human-animal interactions, and canine health.

Researchers hope the node will shed light not only on how dog ownership influences human health in the community, but also on how these benefits could be harnessed as part of the health care system.