Which breed has the most acute sense of smell and is used in tracking?

The breed with the most acute sense of smell, widely used for tracking, is the Bloodhound. This large scent hound can follow human scent over great distances, even when the trail is several days old.

Bloodhounds probably descend partly from hounds associated with the Abbey of Saint-Hubert in Belgium. By the Middle Ages, they were prized for hunting deer and wild boar, especially for locating an animal before the chase began. Their long ears, loose facial skin, and powerful nose are closely associated with their tracking work.

From the 14th century onward, English writings describe Bloodhounds as people-trackers. They were used to follow thieves, poachers, escaped prisoners, missing people, and lost pets. A famous 17th-century account describes a Bloodhound tracking a man for seven miles and finding him upstairs in a house.

A common mix-up is assuming the name means the dog only follows blood. In practice, the breed is valued for identifying and pursuing individual human scent, while its independent, persistent nature can make obedience training challenging.