dog on an elevator

So this morning I had to share an elevator with a dog and it bothered me some.

I don't dislike dogs... on the street, in their owner's home, in a dog park, even in the workplace if it's fairly well known that there will be dogs.

I worked with a company who's director kept 2 fairly substantial beasts around, and I was informed prior to the interview about the dogs so if I didn't want to (or couldn't) be around them on a daily basis, it was my choice.

But something about a 50 lb dog in a small, packed elevator felt incredibly presumptuous and entitled - she wasn't disabled and there were no identifying markers of a seeing eye dog on the harness. How do I know your dog is trained to be in that situation?

Next time maybe wait for an empty elevator... take the stairs?
If I weren't pushed to the back corner of the car where she got on, I would have exited and gone another way myself.

And I know this a is a touchy subject, but I can't help but have a negative reaction to it... Times weighs in here.

UPDATE: I've been thinking alot this morning about why this experience bothered me so much. I like dogs. I like dogs in offices - it does tend to humanize the environment. Upon reflection, I've worked at no less than 5 places that had dogs around, and I never batted an eye. I'm not an advocate of those with allergies, or really worried about the dog's behavior - it was fine in the elevator.

At first I thought it was the slippery slope argument - "If she brings her dog and it's ok, what happens if that guy brings his, and that woman hers, then there are exponentially more dogs over time, doing uncontrollable dog-like things."

But I know that the slippery slope argument is a well known logical fallacy.

So where does that leave me... was I simply being unreasonable?
Maybe I'm bothered that she appeared to value the comfort of her dog over the potential discomfort of those around her.
What if it wasn't a dog, but a heavily laden rolling cart - I'm thinking that holding the elevator up and shoving herself in may have provoked the same reaction.

So I think my reaction is rooted in my intense frustration with those who are not aware of the world around them - and she's now lumped in with those who don't use turn signals - or the hipster man-child who parked his bike in a driveway - or the people who stop at the bottom of the escalator to get their bearings and block everyone else from getting off.