Dogs watch us all the time and read our body language like a sixth sense. They also smell our bodies for changes. Max smelt cancer in Maureen before any medical scans could pick it up. Dogs do this naturally and can be trained to pick up on tiny volatile chemicals given off by cancerous tumors. They can even be taught to alert diabetics to low blood sugar levels.

Subscribe to BBC Earth: http://www.youtube.com/subscription_center?add_user=BBCEarth
BBC Earth YouTube Channel: http://www.youtube.com/BBCEarth

BBC Earth Facebook http://www.facebook.com/bbcearth (ex-UK only)
BBC Earth Twitter http://www.twitter.com/bbcearth

Visit http://www.bbcearth.com for all the latest animal news and wildlife videos

This is a channel from BBC Worldwide who help fund new BBC programmes.