bloodhound

noun

1. one of a breed of medium- to large-sized dogs, usually having a black-and-tan coat, very long ears, loose skin, and an acute sense of smell: used chiefly for following human scents.
2. a person who is a steadfast pursuer.

noun

1. a large breed of hound having a smooth glossy coat of red, tan, or black and loose wrinkled skin on its head: formerly much used in tracking and police work
2. informal a detective