We live on the top (second) floor of a two family house, and there is a French-paned door at the bottom of the stairs. When we’re home, we leave the apartment door opened, the other door closed, and let the animals go up and down. Initially, this seemed like a good idea and a way for the cats and dog to get both exercise and entertainment.
It’s doubtful that Gramercy had ever seen stairs before coming here, and initially, he would look at them, extend a paw, and meowl for all he was worth, which is a considerable amount. Having figured out what to do with them, he goes to the bottom and meowls, for all he’s worth, sometimes loud enough to engage the dog on the first floor.
Hayes had seen stairs before, when we lived with Nancy, but those stairs were in a barn and he learned how to track on mice, if not exactly how to catch them. He goes halfway down the stairs and looks around, presumably for mice. If any existed, we haven’t been gifted with them.
Morgan has been up and down stairs since she was a puppy, but here, she never seems sure of the protocol. Last night, as we were headed out to the pub, we chased the animals upstairs and into the apartment, but Morgan, who had only gone down a few steps, got confused. She did not turn around. She went up backwards. On her butt.
There might be less graceful members of the canine world, but I most sincerely doubt it.
My cats are all climbers, so even the near-vertical ladder to the attic (where it's warmer, usually) is no problem. And one of their favorite games when the weather is foul is down the front stairs, tear through the first (American) floor, up the back stairs, tear around the second floor, and repeat. All the rugs are permanently rucked up.
I was on a boat (100' schooner) with three dogs (two of them small), and they all could climb and descend pretty steep ladders. They could all jump/scramble over the splashboards to get on deck, but they also knew that jumping the other way was a bad idea. They also knew to do their excretory business on the foredeck.
It's just a matter of what they're used to.