Why is a Dog's Sense of Smell So Powerful?

A dog relies on her sense of smell to interpret her world, in much the same way as people depend on their sight.   How can a dog’s sense of smell be so keen?  First, they have many more scent-detecting cells than humans.  Take a look at this comparison:

Species                                     Number of Scent Receptors

Humans                                             5 million

Dachshund                                     125 million

Fox Terrier                                     147 million

Beagle                                            225 million

German Shepherd                          225 million

Bloodhound                                   300 million

A dog's brain is also specialized for identifying scents. The percentage of the dog's brain that is devoted to analyzing smells is actually 40 times larger than that of a human! It's been estimated that dogs can identify smells somewhere between 1,000 to 10,000 times better than nasally challenged humans can.

Dogs are incredible!