Essence of C-diff Odour; What a Dog Detects

A Little Background About Odour Molecules

C-diff odour molecules are shed and become airborne, they expand in a cone shape plume, and are pushed around by air movement.
This air movement is a significant factor in K9 scent detection, it is influenced by temperature, humidity, heat from equipment and lights, open doors, and people walking by.   Finley finds and follows the strongest odour of C-diff.

In general, C-diff odour molecules that a dog can smell are:
  • - Microscopic trace amounts of 5 VOC's
  • - Lightweight and move in the air.
  • - Dissipate quickly, but are constantly generated from the CFU's
  • - Rise upward by heat and fall in a circulating pattern.
  • - Pushed and collects in corners.
- The odour shedding is consistently refreshed.

The Target Odour

Healthy human stool has hundreds of compounds which give off odours. Studies show that there are eight or more volatile organic compounds present in stool with C-diff which are not present in non-C-diff stool. It appears that there is a minimal odour variance by C-diff strain, and we suspect our dog searches for the unique VOC’s.
(propan-1-ol, 3-methylbutanal, ethyl propionate, hexanoic acid, 4-methylphenol, dodecane and indole)


We  train by following specific guidelines high standards for searching in a hospital.   We place odour enhanced tips in a series of scent boxes.  We choose to use cotton tips in  a small aluminum tin with a slide cover because it’s  safe to use and not usually seen in a hospital.  Each hide has a florescent marker and a label to identify the content.  

Locating the Source with Nose and Brains

Finding it.....

This storage area was closed when Finley showed strong interest.   When opened, he tried to crawl under the bottom shelf, then dove onto the left corner and did his classic “I found it” thing.

We know that odour is transient, so is it reasonable to conclude that  the C-diff colony might not be on the shelf?   Maybe it's on the wood door?  Or on the very top shelf?   

Often he'll park his nose right on the contact, and sometimes he lets us find the exact source.


Things We Know

  • - In scent box exercises and in clinical areas he strongly alerts to 027 positive and 027 negative.
  • - He can tell us that a room does not have colonized C-diff - in seconds.
  • - There is no mistaking his change in body language when he first encounters the C-diff scent cone.
       This behaviour change can be subtle, and sometimes very dynamic.
  • - We train to get within centimeters of a colony.

  We were leaving ICU and Finley exhibited classic signs of being ‘on odour’.   His  head was quickly moving left and right and he was rapidly sniffing.  He closed in on the blue equipment cart and put his front feet up on the top level and continued to sniff rapidly. He moved to the yellow isolation cart on the left and  pawed at the lower corner to completed his alert.

Finley has walked by this cabinet six times in the last few weeks, but he alerted today.   The team found a colony of C-diff, Is it a new source or recently disturbed?     


Building the C-diff Search Protocols

We started to locate C-diff by doing comprehensive research on how others trained their dogs for various disciplines.
We visited BC and Michigan, we met with top scent detection professionals, and communicated with recognized experts.

It's a unique discipline, and Finley has trained daily for a year and a half. Every day we gain experience and understanding of the complicated task of locating C-diff on surfaces. We have written the standards for Interior Search with Hospital Protocols.

Doing Good Work

Make contact by e-mail or call 705-718=9711