Spend the energy before the first bang
A Doberman who has worked hard settles measurably better than one carrying a full day of unused energy into a noisy night. In the afternoon, give him a proper training walk with obedience woven through it, some controlled fetch and a chance to sniff himself tired, then feed him earlier than usual. Mental work matters as much as the walking itself for this breed: ten minutes of heelwork, place practice and food searches tire a Doberman brain in a way plain walking does not. Aim to be home, doors closed, an hour before displays usually start, because a Doberman caught outside by the first unexpected rocket is a very strong dog to hold on a lead.
A room that can handle pacing and weight
Choose the room by strength, not by where he usually sleeps. A panicking Doberman can push through a flimsy internal door, crack a window with a paw or tip furniture while scrambling, so pick an interior room with a solid door, move ornaments and floor lamps out, close the curtains and lay his bed where he can walk a loop around it. Many Dobermans pace, check their person, then lie down in cycles, so give the loop room rather than shutting him in a crate he does not already love. If he is crate-trained and chooses it, leave the crate door open inside the room so it stays a refuge rather than a trap.
Your presence is this breed's anchor
Dobermans are famously attached, and isolation during fireworks often reads to them as abandonment on top of noise. Sit in the room with him, read or watch something ordinary, and keep your voice and movements unhurried. Let him lean against your legs if he seeks contact, but do not haul him into cuddles if he prefers to pace. Avoid a houseful of guests fussing over him, and keep children from crowding a stressed dog of this size, however gentle he normally is. If he barks at bangs, let him; punishing the noise response of a frightened guardian breed only adds your anger to his list of threats.
When worry tips into a vet call
Panting, drooling, whining and refusing food during a display are common stress signs in Dobermans and usually fade within hours of quiet. Contact a veterinarian promptly if he has injured himself on a door or window, if he vomits repeatedly, if his abdomen looks swollen and he retches without bringing anything up, or if he is still frantic and unable to rest long after the noise has ended. Bloat-type signs in a deep-chested breed are always urgent, fireworks or not. Afterwards, write down what actually helped, whether it was the room, the pacing loop or your presence, while you remember it clearly.
A loose, frightened Doberman alarms strangers even when he is friendly, which can slow his rescue, so KinsLe's Lost Pet Alert System helps by alerting nearby members who are ready to help and letting a finder contact you directly through his profile.