Therapy Dogs May Carry Germs

Study shows pathogens may transfer between patients and dogs in healthcare facilities.

By Wendy Bedwell-Wilson (
Posted: June 23, 2009

A new study of therapy dogs shows these canine workers do more than share smiles; they can also share bacteria commonly found in hospitals.

In a paper titled, “Contamination of pet therapy dogs with MRSA and Clostridium difficile,” published online on March 28, 2009, in the Journal of Hospital Infection, researchers from the University of Guelph in Ontario, Canada, reported that methicillin-resistant staphylococcus (MRSA) and C. difficile may have been transferred to the fur and paws of these canine visitors when patients handled or kissed the dogs, or through exposure to a contaminated healthcare environment.

Investigators examined 26 therapy dog-and-handler teams between June and August 2007. Twelve teams visited acute-care facilities and 14 visited long-term care facilities. Prior to each visit, the dog’s forepaws and their handlers’ hands were tested for MRSA, vancomycin-resistant enterocci and C. difficile. In addition, the investigator sanitized her hands, handled each dog, then tested her hands for the same pathogens.

Testing was repeated on departure from the facility. The dog-and-handler teams were observed at all times during the visits, and all interactions with patients and staff were closely monitored.

Prior to the visits, none of the tested pathogens were found on the hands of the investigator or the handlers, or the paws of the therapy dogs. But after visiting an acute-care facility, one dog was found to have C. difficile on its paws. It was observed giving its paw to many of the patients.

When the investigator’s hands were tested after handling another dog that had just visited a long-term care facility, MRSA was detected, suggesting the dog had acquired MRSA on its fur. It had been allowed onto patients’ beds and was seen to be repeatedly kissed by two patients.

Finding MRSA on the hands of the investigator who petted a dog after its visit to the facility suggests that dogs that have picked up these pathogens can transfer them back to people. Even transient contamination presents a new avenue for transmission, not only for the pathogens evaluated in the study, but potentially for others, such as influenza and norovirus.

The authors conclude that to contain the transmission of pathogens through contact with therapy animals, all patients and handlers should follow recommended hand-sanitation procedures.

“It’s unrealistic to think that we can sanitize an animal visitor’s body between patients,” says investigator Sandra Lefebvre of the University of Guelph’s Ontario Veterinary College. “But we can and do ask human visitors to sanitize their hands so they don’t spread germs.”