March 15th, 2016

Dogs Again Are Brilliant Diagnosticians

The reputation of dogs in the ID world got a big boost when Dutch researchers published this remarkable study of Cliff — a beagle who was trained to “diagnose” C diff using his superior olfactory abilities.

(A couple of entertaining videos here, if you can’t get enough of this stuff. I can’t.)

Now, in the pages of Open Forum Infectious Diseases (IDSA’s open access journal, of which I’m editor), we’ve published another landmark study demonstrating the extraordinary sniffing powers of our best friends:


From the paper:

In this double-blinded case-control validation study, we obtained fresh urine samples daily in a consecutive case series over 16 weeks. Dogs were trained to distinguish urine samples that were culture-positive for bacteriuria from those of culture-negative controls, using reward-based clicker/treat methods …Dogs detected urine samples positive for 100,000 cfu/mL E. coli (N=250 trials; sensitivity 99.6%, specificity 91.5%).

Impressive! Not only that, but the pooches did equally well with other bacteria — Klebsiella, enterococcus, Staph aureus. An anecdote in the Discussion section of the paper highlighted the real-world performance of Abe (he’s a dog) when a sick person visited the training center — I encourage you to read the full paper (which is on OFID’s early access page) for the details. Not only that, but there’s an action shot of the experimental methods.

So how do the dogs do so well at this task? To start, it is estimated that a dog’s nose is over 100,000 times more sensitive than ours. Plus, there’s this astute comment from my Twitter feed:

twitter comment on dog study

Indeed, this diagnostic task is right in the “sweet spot”, as it were, of a dog’s abilities. As the paper notes, “Sniffing urine is innate behavior in dogs.”

Practice makes perfect. Woof!


9 Responses to “Dogs Again Are Brilliant Diagnosticians”

  1. Loretta S says:

    Abe is my new hero. (I won’t spoil the surprise for other readers by explaining why.)

  2. D.K. says:

    Brilliant indeed! Such exciting research.

  3. mbb says:

    very cool, but how about distinguishing bacteriuria from true UTI?

    • Loretta S says:

      The definition of a “case” in the study was a culture-positive urine sample with 100,000 cfu/mL E. coli or more. The controls were completely culture-negative. I agree that it would be important to know if the dogs can distinguish low levels of bacteriuria from 100,000 cfu/mL or more of bacteria. But the authors note that this method might be particularly helpful in patient populations, such as those with neurogenic bladder, who might not show symptoms. And the threshold for treatment of UTI in neurogenic bladder is lower than 100,000 cfu/mL.

      At the end of the paper, in “Future Directions”, the authors note, “”In future work, we plan to address additional questions that were not within the scope of this study, including testing samples containing mixed bacterial cultures, and finding the dogs’ lower limit of detection. Assessing negative predictive values for clinical syndromes could be an important aim of future studies.”

      Wow, Paul, I can’t believe you got me reading that article in-depth!

      So we’ll have to stay tuned. 🙂 Meanwhile, Good boy, Abe!

  4. Louise Leger says:

    My daughter had a dog that kept licking a mold on her leg. My daughter went to a doctor and was diagnosed with melanoma. It’s been over 5 years now and all is well. Thanks Sadie!

  5. Susan Larrabee says:

    My son’s puppy eats poop. How ’bout that? :0

    • Paul Sax says:

      It’s just a phase (he/she will outgrow it). But yes, pups can be disgusting at times!

  6. Maurice S says:

    Here’s to 10,000 hours of sniffing pee and poo!

  7. Maureen Maurer says:

    The idea for our study was inspired by our Service Dog clients, many of whom have frequent UTIs.

    Several years ago, two of our three clients (one with SCI, one with MS) attending the two week team training camp were hospitalized for complications from UTIs.

    At the time, I was in grad school studying how dogs can detect cancer and thought it might be possible to apply those methods to teach Service Dogs to provide early detection of UTIs for their partners.

HIV Information: Author Paul Sax, M.D.

Paul E. Sax, MD

Contributing Editor

NEJM Journal Watch
Infectious Diseases

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