Dogs are recognised to have the keenest of noses and have been used for detecting illicit drugs, early stage cancer and even C. difficile including an outbreak (possibly a cheaper option than PCR for screening – I should have used this in my debate with Jon). Now a new study finds that trained dogs can reliably detect significant bacteriuria.
In this double-blinded, case control study Dogs detected urine samples positive for 100 000 colony-forming units/mL Escherichia coli with 99.6% sensitivity and 91.5% specificity. Very similar results were obtained for Enterococci, Klebsiellae, and Staph aureus. Interestingly most of the specimens came from females and it would be interesting to see if there were any differences there. Trained Labradors and Golden Retrievers were used and the dogs were trained for 8 weeks using rewards for correct detection.
Now I’m not a fan of dogs (my partner has one) but even I can see that they can be useful sometimes. How this would fit into clinical practice I’m not sure however it would be interesting to see how someone would get on if they submitted this as an idea to the Longitude Prize. Quick, cheap method of detecting significant bacteriuria that could be used for assistance dogs? The authors suggest that training for pneumonia detection from breath might be possible, which would certainly help all of those double-blind studies (also known as Orthopaedic Surgeons looking at a chest X-Ray).
Reflections on Infection Prevention and Control 
Interesting! However, I see one important limitation: dogs have to be trained for a certain smell (in this case pathogen). So if a dog is trained for E. coli but the patient this time has an enterococcal infection, he will not alert.
Another point is that dogs have to be exposed to the smell in training several time, like ” refresher courses” so although I must say I am impressed with the quality of their nose I see problems in real life applications. We did an experiment with a dog to see if she could detect Influenza virus, in the end we did not succeed since we found out she was not detecting the virus but the smell of decay from the culture cells. Still no mean feat if you can distinguish between metal objects that are swabbed with fresh cell culture medium from ones that swabbed with cell culture medium that were infected by viruses.
As for smelling pulmunary infections: there are several studies using Giant Rats to smell TBC. I think that is a very promising initative, since I think it would be best to use animal noses in settings where a quick screening of a lot of people is a way of limiting spread of pathogens, not so much in one-on-one diagnosing infections. Labs are better at that. Labs as in laboratories 😉
Last point:
Let’s not forget that dogs are living things and their behaviour is influenced by many things: a dog that does not feel well might not be functioning as well f.i. As dog lover & dog detection enthousiast (both my dogs do man-trailing courses) I am still very sceptical for real life applications.
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Yes, I agree. It would be great if what the dog is actually sensing could be incorporated into an electronic nose. There was some interest in this a few years ago http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=403480&fileId=S0022215104001884. Added advantage in that you don’t have to take the nose for a walk around the block with a small plastic bag..
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