Here's Schatzi, working through a cancer detection scenario with disease controls and distractor scents. Once again, we challenge the dog to become more and more specific throughout his training. Distractor scents (strange or exciting scents that may cause a dog to false alert) are put into the mix once a dog is fully trained and advanced. We then add in disease controls (diseases other than cancer) and distractor scents (cat urine, dead animal, female in season, etc...). The dog must learn to IGNORE ANY AND ALL OTHER SCENTS except the exact combination of volatile organic compounds which make up "cancer". Schatzi never gives false positives, and this is because of the rigorous training techniques that are taught from early on in the dogs training.