You always see them hunting down fugitives in the movies, but is that just Hollywood, or are bloodhounds really the best smellers around?
Bloodhounds are pretty much the best in the business. Sometimes called noses with paws, their skills as trackers come from the high number of olfactory receptors — or “scent cells" — tucked up in their wet noses, which detect odor molecules. A human's olfactory membrane is about the size of a postage stamp and contains 5 million receptors. A large dog like a German Shepherd, meanwhile, has a larger membrane and about 225 million receptors.
The scent hounds, a group of dogs that includes foxhounds, beagles, catahoulas, blood hounds and other breeds, blow the rest of the pooches and their masters out of the water. These dogs have wide, deep nasal cavities that can accommodate sizable olfactory membranes and large numbers of odor-detecting cells. The little beagle, often no more than half the size of a German Shepherd, has the same number of olfactory receptors as the larger dog. The bloodhound is the grand champ of scent cells and weighs in with 300 million of them, the most in the canine family.
Scent cells aren't the whole story, though, and the breed has a few other attributes that help when it comes to tracking. Their droopy ears and wrinkly skin help collect odor molecules and sweep them towards the dogs' noses. Their muscular necks and shoulders let them keep their nose to the ground for long distances without getting fatigued. Bloodhound handlers also say that the breed is a joy to work with. The dogs interact well with people, are eager to please, and are focused in training and on the job.