We have cats. They roam where the snakes and rats are. They never bother any of them. However, hubby used to have an anole tank. One cat in particular wouldn't leave that alone. And did the same thing, knocked it off and broke the tank.
We also have one rat colony the bedroom, where the littlest boa is kept (for now). As well as pet rats and a hamster In the living room, where the two bigger boas are, and haven't had any problems. Maybe they are just used to it, since it's always there?