E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Mauthe Dog.
A “spectre hound” that for many years haunted the ancient castle of Peel town, in the Isle of Man. This black spaniel used to enter the guard-room as soon as candles were lighted, and leave it at day-break. While this spectre-dog was present the soldiers forebore all oaths and profane talk. One day a drunken trooper entered the guard-house alone out of bravado, but lost his speech and died in three days: Scott refers to it in his Lay of the Last Minstrel, vi. stanza 26.
1
For the legend, see a long note at the beginning of Scott’s Peveril of the Peak, chapter XV.
For the legend, see a long note at the beginning of Scott’s Peveril of the Peak, chapter 
