I live on an island where most of the houses are on stilts and dogs have to learn how to negotiate the stairs early on. I think the issue is to not let them race down the stairs because it can be dangerous, just as it would be for a child or anyone really. I carried Sawyer up and down the stairs until he became too heavy, but now carrying a 50 lb.-and-still-growing guy up and down the stairs every time he needs to pee is really not an option so I use a leash to control his speed.