Nice piece in New Scientist, on more work by Alexandra Horowitz:
To imagine the scent-based world of a dog, says Horowitz, look around and imagine that everything you see has its own individual scent. And not just each object – different parts of the same object may hold different types of information. Horowitz gives the example of a rose: each petal might have a different scent, telling the dog it has been visited by different insects that left telltale traces of pollen from other flowers. Besides picking up on the individual scent of humans that had touched the flower, it could even guess when they may have passed by.