According to several shelter websites and Caesar Milan's website, the 4th of July is the day of the year most pets run away from home. The loud, hissing noises and the final explosion can stimulate the fight or flight in your dog. In most situations he will choose "flight" and will head for the hills.
If you live near a fireworks venue and you are not going to be home, make sure your dog is properly kenneled and of course has proper identification such as a collar and tag and/or a Home Again Microchip. I do not recommend having pets tethered outside as they are great magicians at getting loose. The best option is to leave them inside in a kennel or board them at a boarding facility.
Some pets may not be phased by the sight and sound of the fireworks, but I still do not recommend having the dog join the family. Curious and playful dogs have been known to "attack" fireworks causing severe burns to the face and paws. Not to mention, unused fireworks contain toxic substances if ingested.
If you were considering taking your pet along for the ride, might I suggest leaving them at home. Throw him or her a few extra treats as you and your friends head out the door, and I can assure you he will be happy to see you come home. If the unfortunate does happen and you find your dog is missing, immediately call the local shelters, your veterinarian and surrounding veterinarians and if your pet has a microchip, call the company with which he is registered.
From all of us at Leesburg Animal Hospital, have a Happy 4th of July and stay safe! Don't drink and drive!