The Humane Society says that July fifth is the busiest day of the year for animal shelters.
PET MD suggests keeping your pets indoors until the fifth. Don't take your dog to a fireworks display. Keep identifying tags on your pet and have them microchipped (Tags and collars can get ripped off). Don't use fireworks around your pets.
If you think about it, the sky is exploding and flashing for no reason. And when an animal isn't desensitized enough to oddball events around him/her, it can be a devastating emotional experience. And unlike humans who can reason through something that startles them, sometimes animals just RUN! Their fight or flight mode kicks in and doesn't shut off until they feel safe or run out of energy.
And that flight mode is pure adrenaline, with no logic attached. They don't run for cover all the time. They don't get to a safe spot... they just run, run and run some more. They run with no intelligence or logic attached. During earthquakes dogs bolt from their homes and run like mad. Then they get lost or killed when they get hit on the highways.
If you think your fence will keep them in the back yard, you will probably be statistically correct. Yet if your dog has never attempted to leap over your six-foot tall fence, most mid-sized to large dogs just might amaze you what they can truly be physically capable of.
Don't take the chance.