Can I use waterproofing spray on my Doc Martens?

Or will it ruin them? Are they already waterproof? I'd like to be able to wear them in the winter, but it's really snowy where I live. Also, will it affect stitching in any way, the ones I own have a flower design sewn on the side, this is a picture of them: a href="http://www.drmartens.com/ProductDetail.asp?PID=13242001" rel="nofollow"http://www.drmartens.com/ProductDetail.a…/a