It's not a question of "can" you can get a horse into a hotel room. That question has been answered. The real questions are "why," "how," and, "now what?"
First, you have to get your horse up the stairs. Or perhaps in the elevator. Both pose interesting problems, such as "do horse knees work on stairs," "can an elevator sustain the weight of a horse," and "are horse hooves okay on carpet?" Then you have to think about how you'll get the horse down the stairs. Going up the stairs is one thing. Going down seems like a recipe for the horse to slip, fall, and become a mangle of broken legs and hooves by the time it reaches the bottom.
But say you do get the horse up to the floor your room is on. Now you've got a horse in your hotel room. Hotel rooms are not famous for their roomy, charitably laid-out design. If your horse doesn't trip over an ottoman in the first 15-seconds of being in the room, that's one nimble-ass ungulate. And even if your horse manages to tip-toe around the various odds and ends in a cramped hotel room, there's one absolutely unavoidable inevitability: the gargantuan dumps. Horses poop and pee commensurate with their size.
I'm talking five milk-jugs full of horse pee, all emptied onto the carpet. Imagine when housekeeping walks in to see the devastation that has laid waste to the carpet. Dog-sized mounds of horse poop, and the entire carpet moist with urine. That's enough to make even the most patient hotel worker snap. They see that, they're not going to fold your towels in the shape of a swan. They're going to take one look at that scene, start dumping gasoline on the floor, and flick a lit match as they slowly walk away, eyes blank and haunted.
At least this story clears up one thing. Whenever I sleep at a hotel, I wonder what could possibly be making that clomping noise upstairs, "Is there a literal horse up there?" I exclaim to my towel-swan. Apparently, the answer is yes. And that faint damp spot forming on my ceiling is its rapidly expanding pool of urine.