In B.A. Botkin's "Treasury Of American Folklore" (p.19) is a story taken from 'Sketches & Eccentricities of Col. David Crokett, of West Tennessee" mentioning tha "Davy Crokett's dog was named 'Ratler'".

From the glossary of "Wake Up Dead Man"
Rattler: The original tracking hound, the one who can follow any trail, walk a log, swim the treacherous Brazos River. I've been told that it is traditionalto name at least one dog on each farm Rattler.

Barry