Hospitals across Canada use therapy dogs to bring patients cheer and some friendly companionship, but a new report says the animals also bring something else: potentially harmful bacteria.

Researchers at the University of Guelph's Ontario Veterinary College tested 102 therapy dogs. They found 80 per cent of them carried pathogens that could be transferred to people, including E. coli and salmonella.

"It's surprising, because if we looked at normal dogs, we'd only find a few of them carrying the bug," researcher Prof. Scott Weese told CTV News.

The Journal of Hospital Infection published the findings, which highlight the risk of bringing animals into hospitals to cheer up patients.

But researchers pointed out that there's no evidence the dogs make patients ill, or whether the dogs pick up the bacteria from patients.

If anything, the report shows the need to monitor hospital infection control practices.

"I've seen patients actually consume food after handling dogs without washing their hands ... and that concerns me," said researcher Dr. Sandra Lefebvre.

Researchers suggest hospitals may want to reconsider whether therapy dogs should be allowed into critical units, or anywhere near infectious patients who could pass their diseases on to others by way of the animals.

Marilyn Benoit, from Ottawa Pet Therapy Dogs, insisted that her charitable organization ensures patients don't risk their health when they meet the group's animals.

"We go out with clean, well-groomed dogs," she said.

Organizations like Ottawa Pet Therapy Dogs have strict standards of cleanliness for their dogs, to minimize any danger of spreading infectious diseases.

The animals are thoroughly cleaned before taken inside any hospitals, while patients and staff are asked to wash their hands after handling the dogs.

"If we can assure the public that we are taking the necessary measures to protect everybody, I believe in the end the pet therapy which is hugely valuable to patients in facilities, will be continued," Benoit said.

By monitoring safety measure, groups hope hospitals won't have to balance the benefits of therapy dogs against the potential for harm.

Source: CTV's Avis Favaro