Spend a Jack Russell's energy before dark
A Jack Russell Terrier handles fireworks night best on empty batteries. Give him a genuinely tiring afternoon: a long walk with plenty of slopes, a ball session, and ten minutes of training games that make him think, because a mentally worked terrier settles in a way a merely walked one does not. Feed him early and bring him in before the first displays, with curtains drawn and the television up loud enough to blunt the irregular bangs. A Jack Russell left under-exercised will spend the evening inventing his own entertainment, and on fireworks night that invention usually involves your fence, your doors, or your skirting boards.
Terrier-proofing: assume he is planning something
Fireworks safety for a Jack Russell Terrier means auditing your home like an escape artist's owner. Walk the fence line looking for the soft earth where digging has started, check that gates latch against a determined shoulder, and block the dog flap and cat flap, since a Russell can pour himself through both. Close windows he could reach from furniture, and keep him out of rooms with doors opening directly outside when guests arrive. Fit his collar and ID snugly before dark, and keep him on a lead even for garden toilet trips; this breed was made to go to ground after quarry, and a terrified Russell who finds a gap will be under the fence and gone while a slower dog is still deciding.
Give the busy brain a legal target
During the fireworks, a Jack Russell Terrier needs occupation more than cuddles. Offer a frozen stuffed toy, a puzzle feeder, or a cardboard box he is explicitly allowed to shred in his corner, and rotate to a fresh one when the first is demolished. Play short, familiar games in the room if he is willing, keeping energy cheerful and low-key. If he barks at the bangs, do not shout over him; redirect onto a trained behavior he knows well, like a hand touch, and reward it. Some Russells settle under a blanket in an open crate; others pace and patrol. Pacing with a toy in his mouth is this breed coping — let him do his rounds of the room rather than confining him tighter.
Hunting for a Russell who got out
A Jack Russell Terrier lost on fireworks night is probably closer than you think and harder to reach: terriers go to ground in drains, under sheds, and into burrows and outbuildings, and a frightened one may stay silent while you call from two gardens away. Search with a torch at ground level, check every outbuilding yourself rather than assuming, and ask neighbors to open sheds and garages while you wait, since a trapped terrier may only bolt when the door lifts. Leave his bedding and a strong-smelling meal near your door in case he doubles back along his own routes.
Getting word out quickly multiplies your eyes, and KinsLe's Lost Pet Alert System does that for a Russell owner at no cost, alerting nearby Circle of Love members while a finder who coaxes him out can message you directly.