Toronto hospital study shows C. Difficile detection dogs not quite up to snuff for early hospital diagnosis

Chase, a Border Collie Pointer and Piper, a German Sheppard, participated in a first of its kind trial at Michael Garron Hospital to determine the reliability of canine skills when it comes to diagnosing C. difficile in a hospital setting. In total, the dogs were tested on 300 specimens over several days.

(August 15, 2018) Toronto – They’re cute and patients like having them in the hospital, but researchers at Michael Garron Hospital (MGH) in Toronto have shown that dogs are not a reliable way to diagnose C. difficile, a debilitating bacterial infection that causes severe diarrhea in hospitalized patients.

Published in Open Forum Infectious Diseases, the study is the first ever to compare two dogs to detect the scent of C. difficile.  Previous studies in Canada and the Netherlands showed two individual dogs could be trained to identify the deadly bacteria, but multiple dogs need to be studied at the same time to see if they consistently and accurately “agree” on whether a specimen is positive or negative. This is known as interrater reliability, which is a fundamental requirement for any test used to diagnose a disease or condition. Lab tests for C. difficile are consistently 99 per cent accurate, although they can take up to 48 hours for a result.

In the Michael Garron Hospital study, two dogs (Chase, a Border Collie Pointer and Piper, a German Sheppard) were Michael Garron Hospital. Although the dogs were able to correctly identify positive specimens about 85 per cent of the time, they did not agree with each other often enough to make dog detection for C. difficile reliable.

 “We’re talking about a highly-transmissible and dangerous bacteria, and when people’s lives are at stake, you can’t be swayed by the cuteness or affection of an animal,” says Dr. Jeff Powis, Infectious Disease Specialist and senior author of the study. 

“We need a test that consistently gives us results we can trust. We wish the lab provided results more rapidly – like a dog could – but who’s going to accept the dog’s result if it’s not consistently reliable?  And unfortunately, while the dogs were pretty good – they weren’t as good as the lab test.” 

Sniffing out C. difficile: How the trial worked

Once Chase and Piper, both rescue dogs, had mastered a training phase at their owner’s farm, they were tested in an unused wing of Michael Garron Hospital. This helped give the dogs a sense of what a “real” hospital setting might look like. In the trial itself, C. difficile positive and negative specimens were hidden within small metal boxes in the empty hospital rooms. Neither the dog handler nor the dogs knew which specimens were positive and which were negative. The dogs were trained to sit if they thought there was C. difficile in the box; otherwise, they left the room and carried on.  In total, the dogs were tested on 300 specimens over several days.

Powis admits that by training and testing only two dogs, they can’t say for sure that the results of the study wouldn’t change if someone studied a larger number of other dogs. But after watching the dogs sniff hundreds of stool specimens as part of their training and research in this study, the study’s lead author, Physician Assistant Maureen Taylor doubts dogs will ever be a practical tool for hospital-based disease detection.

“We saw these dogs work very hard with their trainers to learn how to detect C. difficile,” says Taylor. “But at the end of the day, they are dogs, and easily distracted by stuff that’s just part and parcel of the hospital environment – food trays, friendly family members, even the toilets.”

MGH researchers agree that while more rapid diagnosis of C. difficile in hospitals is definitely needed, the solution probably lies in finding ways to accelerate the current testing process, including more timely collection of stool specimens from patients or tests that can give an accurate diagnosis at the bedside.

And although the study didn’t lead to a new career for Chase and Piper, the dogs are taking it in stride.  Chase even found a new home with the family of one of the hospital’s pharmacists.

Fast facts on C. difficile

• C. difficile can cause symptoms ranging from abdominal pain and diarrhea to life-threatening inflammation of the colon.
• Most cases occur in a hospital environment after a patient has taken antibiotics, which can alter the balance of good bacteria in the gut, allowing C. difficile to multiply and cause diarrhea.
• According to Health Quality Ontario, from Jan.1- March 31 2018, there were 636 confirmed cases of hospital-acquired C. difficile in Ontario.

About Michael Garron Hospital

Nestled in the heart of East Toronto, Michael Garron Hospital (MGH) is a vibrant community teaching hospital serving more than 400,000 people in 22 distinct neighbourhoods. For more than 89 years, MGH has delivered high-quality, patient-centred healthcare services to families along the continuum of care, from welcoming a new life to facing end-of-life. MGH has continually renewed its commitment to community by adapting its programs and services to meet the evolving needs of the diverse population it serves. Located in the Toronto Central Local Health Integration Network, MGH is a respected full-service hospital with strong community and research partners, including the University of Toronto.

Media Contact

Erica Di Maio
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Michael Garron Hospital | Toronto East Health Network
Phone: 416-469-6580 ext. 6019 | Email: @email