Photograph your dog like a stranger will see him
The pack starts with pictures taken for identification, not for charm. Capture a straight-on face shot, a full-body side view, and close views of anything that sets your dog apart: a white chest patch, a scar, one floppy ear, a kinked tail, a grey muzzle. Take them in daylight against a plain background, at his level, and retake them after a haircut, as a puppy grows, or as a senior's coat greys, because a search poster showing last year's shaggy coat can make neighbours walk past the clipped dog in front of them. Save the set digitally and print a few copies, since phones die and printers jam at exactly the wrong moment.
Write the description a finder can act on
Alongside the photos, write the plain facts someone needs to recognise and approach your dog safely. Give his name, breed or best description, size and weight, coat colour and length, and the distinguishing marks the photos show. Add a temperament line that protects both dog and finder: friendly and likely to come when called, or nervous and best not chased, with an instruction to phone you and keep eyes on him instead. Record his microchip number and registry, his collar and tag details, and any health need that makes finding him urgent, such as medicine he cannot miss for long. Sign nothing off from memory; check each detail against his records.
Assemble contacts and copies in two places
A pack fails if it sits in one drawer. Keep a printed set at home in a labelled folder with spare posters already drafted, leaving blanks only for the date and where he was last seen, and keep the full set on your phone where you can send it to a printer, a neighbour, or a local group in minutes. List your mobile number first, then a second household phone, your vet, and the microchip registry's number. Include your address and a backup contact outside the household in case you are away when he slips out and someone else starts the search. Check the phone numbers in the pack whenever anyone in the house changes theirs.
Rehearse the first hour before it happens
Decide now what the pack is for: one person searches the immediate streets calling calmly, another phones the vet, warden, shelters, and the chip registry, and the photos go out to neighbours and local groups with the last-seen location. Knowing that split in advance stops a household duplicating the same tasks while nobody makes the calls. Refresh the pack whenever his appearance, your numbers, or his health needs change, and glance at it when you check his tag and chip details. Keep a note of the collar he wears most days too, because a finder may describe what they managed to catch hold of rather than the dog himself. If the worst happens, KinsLe's Lost Pet Alert System puts his alert on the map from his profile at no cost, and anyone who spots him can reach you with a direct message while the search is still young.