What was it?

[iwanttoknow]

I would greatly appreciate any suggestions as to what the following could have been.....I have never told anyone about what I saw because, at first, and for a long time afterword, I thought it was a huge dog. It was about 15 yrs. ago and I was on my way home from work on a small country road on which I lived. Houses are sparsly scattered at varying distances from the road, but mostly a wooded area in E. Tn. So, I was driving and I saw a very, very large and shaggy, completely white dog run across about 50 feet in front of my car from one side of the road into the woods on the other side. I was so surprised at how massive this dog was. It was obviously on all fours and it's fur was very, very long. The most amazing part was it's size! Height; about the height of a large buck deer and very bulky looking. Imagine an overgrown old english sheep dog. That is exactly what it looked like, but they only grow to about 2 feet high and 100 lbs. at the biggest. So, I am left with the question "what was it?" Has anyone here ever heard of a sighting of a BF sighting that was described as looking like a huge dog?