In some of the scariest stories, the dog's death is used to show the evil or danger of the situation. It can be a symbol of the loss of innocence. For instance, in a story where there is an evil entity preying on a family, the dog might be the first to sense it and unfortunately be killed, which sets the tone for how serious and menacing the threat is. However, there are also many really scary stories where the dog doesn't die at all and instead plays a different role like being a protector or a guide through the spooky events.
In Based on a True Story, the dog is alive throughout the story. There are no events that lead to the dog's death. It's one of those things that might be a relief for those who are worried about such outcomes for the canine characters in movies.
It depends. Some movies or books claim to be 'based on a true story' and may include a dog's death as part of the fictionalized version of the true events. However, without specific research into the actual true story that inspired the work, it's hard to say for sure whether the dog's death is a true part of the story or just added for emotional impact.