A dog's sense of smell is much more acute than that of a human, partly due to the difference in how they work. A dog's nose contains more olfactory receptors than a human's which gives it a more developed sense of smell (Tyson, 2012). A dog would be able to smell where another dog has been and then could use it to follow the same path during agility. competition. Dogs are able to recognize different human odors, and therefore are more likely to recognize their handler's odor than that of other people (Schoon, 1996). Studies have also shown that not only can a dog identify a person by smell, they are able to recognize odors coming from different areas of a person when mixed with other samples, for example, a dog might recognize an odor from the hand, or elbow of the same person when given a selection by different people (Schoon et al. al.1994). It was also found that in some cases dogs were able to distinguish between human twins, even when the smell was almost identical (Kalmus, 1995). This shows the range of odors the dog might detect while completing the course, which it should ignore to concentrate on overcoming the odors