Sydney - Old people with pets live longer and are healthier than those who don't share their home with a dog or a cat.

Sadly, research by the Australian National University's Ruth Paslow has exposed this commonly held view as a myth.

After interviewing 2,551 Australians aged 60-64 she reluctantly concluded that pet owners were more likely to be depressed and to take painkillers than the pet-free.

"I would've been happier finding that pets are good for you," Paslow said, "but I wanted to do research that's reliable and statistically sound."

On the other hand, children who grow up in a home with a dog are less likely to be overweight.

Fortunately, Jo Salmon from Melbourne's Deakin University has done research that proves this to be the case.

"We found that young children five to six are 50-per-cent less likely to be overweight or obese if they own a dog," Salmon said.

Surprisingly, Salmon found health benefits from canine-kiddy companionship regardless of regular dog-walking.

"We think they're maybe outside playing with the dog and just spending more energy generally and playing with the dog and in fact it's not through dog walking but just through playing," she said.