Pack slowly and keep one room normal
Dogs read the house through smell and routine. When cupboards empty and boxes appear, the usual signals vanish. Some dogs get clingy, some pace, some start chewing or having accidents.
If you can, pack over a couple of weeks rather than in one weekend. Leave one room alone until the last day, usually the one where your dog rests. Keep the bed, the water bowl, and a few favorite chews there. Feed and walk at the same times you always do. The routine is the thing your dog can hold on to while everything else changes.
Give your dog some extra sniff time on walks. A sniff walk is a calm way to burn off nerves, and it is free.
If your dog has a history of separation distress, practice some short departures during packing season too. A dog who has already learned that you leave and come back will cope with moving day better. Leave a chew, walk out for a minute, and return calmly. Make leaving and arriving boring.