I'm mad at my aunt for her dog's poor behaviour
Why are you mad at your aunt over her dog's behavior?
The dog always scares my parents because it urinates on the floor when it comes to visit.
Pet owner's are expected to train their pets to behave well, but accidents can still happen. You should try to be more understanding if it truly was an accident. Otherwise they may end up feeling really bad.
Well, maybe the dog has a medical problem. I'll ask my aunt what the problem is.
That's a great way to handle it. Perhaps it is something that a veterinarian can help fix. Who knows, you may end up really liking the dog.