The records that earn their place in the file
Start with identity and health, because those are the papers other people ask for. Keep the microchip registration showing the number and the registry holding your contact details, the vaccination record with every booster entered, and your vet's clinical history or at least a summary of major visits, operations, and ongoing issues. Add insurance documents if he is insured, ownership proof such as adoption or purchase papers, and any registration or licence your area requires. Beyond the official set, keep a page of your own: his food and amounts, walk routine, known fears, the commands he answers to, and what a typical good day looks like. That home-written page is the one a sitter, a family member, or an emergency carer will use most, and it is the page nobody else can write for you.
Organise by the questions people actually ask
A file organised by type is faster than one organised by date, because requests always arrive as questions: is he vaccinated, is he insured, who is his vet, what does he eat. Use simple sections for identity, vaccinations, vet visits, insurance, and daily care, with the newest document at the front of each section so the current version is the first thing found. Put a single summary sheet on top of everything with his name, photo, microchip number, vet's phone number, insurer, and your emergency contacts. In an emergency that sheet gets used while the rest of the file is still being opened. Review the file twice a year, remove superseded insurance schedules and old cover notes, and check that the microchip registry still holds your current phone number, because the neatest folder in the world fails if the registry has a number you left behind years ago.
Keep a paper set and a digital set that match
Paper is what you hand across a counter; digital is what survives a house fire, a lost folder, or a holiday abroad when the kennel phones with a question. Photograph or scan every document and store the copies in the same section order as the paper file, so you can talk someone through the digital set while they hold the paper one. Name files plainly with the document and its date rather than a camera's default numbering, and keep the copies somewhere another family member can reach with your permission. After every vet visit, booster, or policy renewal, add the new document the same week; filing systems fail through drift, not design, and a record added late tends to be a record searched for in a drawer instead. When the two sets match, you can answer almost any request in minutes.
What to do with papers when life changes
Moving house, changing vet, switching insurer, or rehoming a dog are the moments paperwork quietly breaks. Update the summary sheet first at each change, then the section behind it, and tell the microchip registry directly rather than assuming your vet has done it. If your dog is ever transferred to a new owner, pass over a copy of the whole file, because his history is part of his welfare, not your filing. Keep records for a dog who has died for a while rather than clearing them out at once; insurance queries and your own questions about what happened can surface later. Gathering the full set once in KinsLe's Pet Passport, with the summary at its front, gives you a single organised record to update at each change instead of three partial ones.