My view on survival situational preparedness is to try out any equipment or tactic to see if its really applicable.
i have not heard anything good about dog food and have certainly not tried it.
i think its more urban legend then anything, as its been in a few movies, where the guy is trying to survive in a post apocalyptic world and is seen storing up and eating dog food. i cant really see that the canning process is any better for dog food then it is for human food. now the processing of the food itself would have to be looked into to see whether or not there is a higher retention of nutritional value , long term for dog food.. but really how would you determine that ?
if your really eating to live and prevent starvation.... who cares what it smells or tastes like, as long as you can keep it down.
dogs for food themselves.. sure why not. as just about any animal would be fine for that purpose.
i have eaten mountain lion steaks, so i figure any other cat would be ok, and i would guess there are those who have eaten coyote, so a domestic breed dog should be fine also. but again, any serious discussion of survival tactics needs to include real trials.
so go buy a can of dog food and try it, see how it tastes, be sure to report it back to us, your results.