http://www.nwherald.com/articles/2007/04/03/news/local/doc4613191f190a9544357037.txt

If you look at the picture in the article, judging from the length between the "fang" marks that must be the world's largest Massasauga that bit this dog. That is a full grown lab and the punture wounds appear to be over an inch apart. I say it was not a Massasauga, maybe not even a snake. No snake was seen, no toxicology was done by a vet.