Commonly known as Blue Tongue. Epizootic Hemoraghic Disease I believe is the scientific name, tongue swells up and they can't drink, they end up dead in a pond or river somewhere.
Thanks, never heard it called EHD before. It was pretty damn dry last year around here, but I've never heard of Blue Tongue being here though. We have plenty of running streams and I don't think the deer have to rely on stagnant water holes.