G. J. N. Wilson described it, based on the accounts of early settlers, in his The Early History of Jackson County, Georgia (1914). He writes,
The wog was said to be a jet-black, long-haired animal about the size of a small horse, but his legs were much shorter, the front ones being some twelve inches longer than the hind ones. This gave him something of the appearance of a huge dog “sitting on its tail,” and when walking seemed to require him to carry forward one side at a time. His tail was very large, all the way of the same size, and at the end of it there was a bunch of entirely white hair at least eight inches long and larger in diameter than the tail itself. Whether sitting, standing or walking this curious appendage was in constant motion from side to side, not as a dog wags his tail, but with a quick upward curve which brought it down with a whizzing sound that could be distinctly heard at least when twenty-five or thirty steps distant. But the most distinguishing feature of this horrid tail was that it revealed the presence of the monster in the dark—the only time he ventured to go abroad. His great red eyes were very repulsive, but not so much so as his forked tongue, the prongs of which were thought to be eight inches long and sometimes played in and out his mouth like those of a mad snake. Really the meanest feature about the beast was that his bear-like head contained a set of great white teeth over which his ugly lips never closed. (46–47)
The wog is also known in nearby Barrow County, where it is sometimes said to protect a mud volcano called the Nodoroc Site: an odd, boggy, bubbling pond near the town of Winder. Local legends say the place was used by the Creeks to execute criminals and then throw the corpses into the bog. Nodoroc is purportedly a Creek word meaning “gateway to hell,” but I’m usually incredibly skeptical of claims about Native American etymologies—especially since there is no “r” sound in the Creek language!
At any rate, the wog seems to me very similar to monstrous dogs found throughout world mythology, from the hellhounds of Ancient Greece to the faery dogs of the British Isles. A while back, I suggested that the extinct Amphicyonids or “bear-dogs” would make a good stand-in for many such creatures.