July 5th is the worst day of the year for lost pets. If you pick up a stray, get the wayward animal scanned for a microchip at the nearest vet or shelter. If there is no chip or if the chip is not registered, start advertising the lost pet - flyers, craigslist, local paper ads, etc..
Hopefully the scariest part of the holiday is over. But pets might be all wound up for the next few days. Keep things as calm as possible.