Sometimes you can just be in the wrong place at the wrong time.  Just plain old bad luck. This is the time of year to be extra cautious, with or without a dog, but dogs do tend to up the ante when moose with calves are involved as they see them as wolves and do what comes naturally, stomp the crap out of threat.  Hope she finds her dog alright. Just part of living with wildlife. A little respect goes a long way.