colloquial for dog, attested from 1898.
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for dawg
Flo was not just mediocre: she was catastrophically tragic, tone-deaf, screechy and, as Randy Jackson would say, “pitchy, dawg!”Dead Cool: Florence Foster Jenkins
July 10, 2010
But of all the panel, it is the Dawg who has truly reached his fork in the road.Ellen's First Night
February 9, 2010
That dawg was as right as possible when I shut up last night, and he couldn't have got out.Uncanny Tales
Set the dawg on me, you did, and then pitched me into the watter.Patience Wins
George Manville Fenn
"Dawg 'ud be apt to tucker out in desert travel," agreed Sandy.
"The kid's lost her father, lost most everything 'cept her dawg," he said to Mormon.
Ef it hadn't been fo' the dawg, she'd have stayed there, to my notion.