sleuthhound

This explains why the dog has sometimes been called a sleuthhound; that is, a dog set upon a sleuth, or trail.

Its speciality—or, if you like, its oddity—was this merciless mercy; the unrelenting sleuthhound who seeks to save and not slay.

From that instant, all pretenses were abandoned, Robert was a sleuthhound on a keen scent.

Enoch Standring had something of the sleuthhound in his nature.

It was the first messenger from Will Leatherbarrow, who hung like a sleuthhound on the trail.