Incredible Sniffer Dogs

How in Gods name do you train a dog to do this
http://www.bbc.co.uk/newsbeat/articles/33835669

I think dogs have a sixth sense so i am not supprised they can sniff out cancers

Dogs have incredibly sensitive olfactory organs so in theory they can detect almost anything.
The trick is to get them to react to specific smells while ignoring others.

I have my doubts about how the treat method will work reliably when ultimately they will only get a treat for a positive result. As soon as the dog cottons on to the fact that it isn't getting a reward unless it demonstrates a particular behaviour then it will learn to do whatever gets it a treat regardless of what it has detected in the sample.
I would have thought that training people to read the dogs reactions in every instance, and giving the dog a treat no matter what the result appears to be, would be a more scientific way of proceeding. But then perhaps the dogs are the smarter members of the operation.

It's long been known that uncontrolled diabetics can have breath smelling of acetone. I gather there are some others that humans can smell also (http://www.dailymail.co.uk/health/articl...SMELL-like.html ). With dogs having an enormous better capability of smell, it makes sense that they can detect even more diseases.

Said many times ,people underestimate the intelligence of dog's.