It's well-known that dogs can detect Terminators, but in James Cameron's original Terminator movie, Kyle Reese almost had a cyborg dog sidekick. It's never been explicitly spelled out onscreen why exactly dogs can tell the difference between man and machine disguised as man, but considering the long, emotional relationship people have with their canine companions, it makes an odd sort of sense. Dogs are called man's best friend for a reason after all, and animals are often thought to have some kind of sixth sense.
Giving Kyle a cyborg dog sidekick certainly would've been an odd move in hindsight, as so much of the tension to be found in The Terminator revolves around the fact that a vulnerable human soldier is all that stands between Sarah Connor and the T-800's wrath. Throwing another robotic character in on the side of good, even one not entirely machine, would make Kyle and Sarah less of an easy target, and turn the tension level down several notches.
At the same time, if cyborgs that look like humans can exist, it stand to reason that cyborgs that look like dogs could too. How exactly one came to be an ally of Kyle's would be a question in need of an answer, but fans never got to find out, as the robo-dog never materialized.
Terminator Almost Included A Cyborg Dog Sidekick For Kyle Reese
As confirmed by James Cameron, Terminator distributor and financial backer Orion Pictures only came to him with two notable ideas to incorporate into the film. While it's hard to imagine anyone daring to offer Cameron notes nowadays, back in 1984, he wasn't yet the "king of the world." Cameron accepted one suggestion, that the romance sub-plot between Kyle and Sarah be expanded upon, which most fans would agree turned out great. However, Cameron balked at Orion's other idea, that Kyle Reese travel back in time with a reprogrammed Terminator dog sidekick, in a purported bid to make the movie more family friendly.
Thankfully, Cameron won the day, as in addition to the aforementioned problem of decreased suspense if Kyle has additional assistance against the T-800, having Kyle backed up by a machine would serve to invalidate one of the movie's central themes. The ending of The Terminator proves that, despite possible casualties along the way, human grit and resourcefulness can indeed win out over a seemingly unstoppable killing machine. Having a machine involved, even an adorable one (and hopefully not one resembling the Black Mirror robot dog seen above), would lessen the strength of Sarah Connor's victory, and Kyle's triumph in keeping her alive long enough to begin her own heroic path.