What a destination vet actually needs
A vet meeting your reptile for the first time — possibly in an emergency, possibly with you flustered — cannot examine the enclosure the animal lives in, and cannot ask its keeper what is normal for it. Your one page replaces all of that. Done well, it lets a stranger understand this animal's life in about two minutes: what it is, how it lives, what it eats, and what has changed lately. That last part is usually the part that matters most.
The contents, animal by animal
Write a separate summary for each reptile, because a page that blends three animals helps none of them. Start with species, age and sex, and give a recent weight or a short line of weight history. Then the environment it actually lives in: the warm-end and cool-end temperatures, the humidity range it is kept at, and the lighting it gets. Then feeding: what it eats, how often, and how the food is supplemented.
Finish with the recent history a vet asks about first — the last feed, the last shed, and any change in appetite, droppings, activity or appearance across the last few weeks — plus a note of any ongoing issue being watched at home. Close the page with your home vet's name and number, so the two clinics can talk to each other directly, and a line describing any distinguishing marks that identify this particular animal.
Keep it honest and current
A summary written once and never updated quietly turns into misinformation. Refresh the weights and the recent-changes line before every trip, and keep the tone factual: 'refused food for ten days, then ate' is useful information, while 'seems a bit off' tells a vet nothing they can use. A phone photo of the home enclosure set-up, kept with the page, answers a dozen follow-up questions at a glance.
A photograph belongs with the page
Clip a clear, recent photograph of each reptile to its summary. Species names get misread and handwriting gets misread, but a photograph of this gecko, with this pattern and this missing toe, settles identity instantly if several animals are travelling or if the vet's team hands over between shifts. The same photograph helps if an animal is ever lost in transit: the summary page becomes a description accurate enough for someone else to search by. Update the photograph whenever the animal changes visibly — after growth, after a shed that alters its colour, or after any injury that leaves a mark.
Paper and phone, both
Keep the summary on your phone for speed, and a printed copy inside each animal's travel container, for the day the phone is dead, lost, or busy being used as a torch. If the reptile is being transported by someone else, the paper copy is the part that actually travels with the animal — which is rather the point of writing it.
Storing that summary in each reptile's Pet Passport on KinsLe keeps the whole packet — identity, history and care details — together in one place, ready to hand to a vet at the destination or at home.