The eastern coyote has been shown, by DNA analysis, to be a hybrid of the western coyote and the eastern red wolf and is consequently much larger than it's western cousin, 35-40lb. and possibly up to 50 lb. versus 25-30lb.

Good info in this regard and on coydogs too here: http://wilddogsne.com/WJ%20NovDec2010%20Coyote.pdf