Dogs have even shorter lifespans in horror movies than minorities, which is pretty impressive. The poor guys inevitably sense something amiss, bark a few times, then run off to their doom. Of course, sometimes they manage to take out tribes of cannibal hill-people as well, but those times are in the .01 percentile. Cats on the other hand always seem to survive. At least long enough to jump out of the cupboard and scare any of the nubile young coeds out of there panties. Which would explain the continued popularity of cats.