See, I don't think of my 80 lb GSD as a "big dog" - I've seen 130+ lb GSDs, and the OP's dog at 150+ I would call big, as are great danes - but I have I friend who constantly is calling him a horse, and insists "No really, he's the size of a pony!" Um, no.
Just because the only dogs you've
been around are 10-40 lbs doesn't mean 80lbs is a big dog. On the large side of medium, sure.
And yet when we take him to the dog park, he is frequently the largest dog there (also the scarediest - first time we took him when he was about six months old he ran and hid behind us FROM A PUG! A six lb PUG!
). Not always, and at least half the GSDs we run in to are larger, but he is on the larger side of dogs in general. But he doesn't seem "big" to me - he's just my dog, and he's perfectly sized.
My SIL is afraid of big dogs, and that combined with my baby's, um, different
ideas of personal boundaries (he's a face-shover - loves nothing more than to come up and get right in your face) resulted in some tense moments a couple christmases ago. I pointed out that my 15lb, 12yo, blind since birth (and very annoyed at having a big rambunctious puppy around) poodle was MUCH more likely to actually bite her, and was much less likely to actually obey commands and generally be a "good" dog, but it had nothing to do with HIM, just with her perception
of him as a "big dog". Nothing I could say or do would persuade her to be less afraid - she had a phobia, and wasn't interested in trying to get over it. (I'm very sympathetic toward phobias - my arachnophobia is the bane of my existance, but I'm constantly working on getting over it, and I actually LIKE spiders. Just not when they pop up near me unexpectedly, y'know? It's the clinging to phobias that bugs me.)
We could also start talking about breed prejudice, which is closely related to size prejudice, but that's probably best for another thread. (And can I just say I LOVE rotties? And "pit bulls". Never met one that wasn't a complete and total sweety unless it was severely abused - can't say the same about many small breed dogs, although I love them, too.)
Oh, and that gets me on a rant about the perception of small v. large dogs - I've met very few aggressive large dogs (not none, but few), but many, many
aggressive small dogs, but people tend to think it's "OK", because you can always just pick up a small dog and remove it. That makes its antisocial behavior more acceptable? Um, no! Don't get me wrong, I love all dogs, small or large, barky and aggressive or placid and quiet, but what is it about having a small dog that makes some people think it's ok to not train or socialize them? People with big dogs could never get away with that. I'll be the first to admit my GSD could use more training (the poodle is pretty much entitled to be a cranky old fart at this point
but in his prime he knew and responded to about 3 dozen commands, and was well socialized, although being blind there were some doggie signals he just didn't get and some tense situations resulted from that), but as soon as we adopted him we were working on polite, social behavior, and obediance to a few basic commands.
Just don't ask me about how to stop the face and crotch shoving.