Tobit's dog appears only twice (in 6:2 and 11:4) and plays no role in the story (actually he accompanies Tobias, Tobit's son). Like many dogs, he just shows up whenever something seems to be going on. This little detail has greatly exercised the commentators, and even now no one seems to know how the dog got into the story.
Tobit's dog also shows up more than you might think in literature. For instance, here he makes an appearance in Tobias Smollett's Roderick Random:
With this view he approached us, with many bows and grimaces, and, after having welcomed Miss Snapper to the place, asked her in the hearing of all present, if she could inform him of the name of Tobit's dog. Miss was so much incensed at his insolence, that I should certainly have kicked him where he stood without ceremony, had not the young lady prevented the effects of my indignation, by replying with the utmost vivacity, "His name was Nash, and an impudent dog he was."Voltaire puts these words in the mouth of a fictitious scholar:
I will show them, with outstretched neck and twisted mouth, that you hold an erroneous opinion in relation to the cells in which the Septuagint was studied; that you have even spoken disrespectfully ten years ago of Tobit's dog, which you asserted to have been a spaniel, while I proved that it was a greyhound.
Jonathan Swift wrote:
THAT Expression in Apocrypha about Tobit, and his Dog following him, I have often heard ridiculed; yet Homer has the same Words of Telemachus more than once; and Virgil says something like it of Evander. And I take the Book of Tobit to be partly poetical.
The militantly Protestant, of course, don't like Tobit or his dog. A character in Walter Scott's Waverley:
‘But if your honour wad consider the case of Tobit — ’
‘Tobit!’ exclaimed Gilfflan, with great heat; ‘Tobit and his dog baith are altogether heathenish and apocryphal, and none but a prelatist or a papist would draw them into question. I doubt I hae been mista’en in you, friend.’
And J. N. Darby, founder of the Plymouth Brethren, has this to say:
Look at Tobit, and his dog; it is absurd! Bel and the dragon may be true, but it has nothing to do with inspiration.
But my favorite mention of the dog comes in Robert Browning's "Ring and the Book":
The dog is also a normal part of the iconography of Tobit. These links give the idea: A B C D E F.LetEach level have its language! Heaven speaks first
To the angel, then the angel tames the word
Down to the ear of Tobit: he, in turn,
Diminishes the message to his dog,
And finally that dog finds how the flea
(Which else, importunate, might check his speed)
Shall learn its hunger must have holiday ...