The 15-Digit Chip: FDX-B Pet Microchips in the UAE and What Your Flap Reads

Inside your cat, roughly the size of a grain of rice and sitting between the shoulder blades, is a chip carrying a single 15-digit number. That number is the whole of your microchip cat flap’s world: it is what the flap reads, the only credential it accepts, and the reason a registered cat walks through while every other animal in the neighbourhood meets a locked door. This guide to the 15-digit FDX-B vet chip explained unpacks what the FDX-B pet microchip UAE vets implant actually is, why the standard matters, and what the chip does — and just as importantly, does not — contain.

What FDX-B means, in plain terms

Pet microchips work to an international standard, ISO 11784 and 11785, so that a chip implanted in one country can be read by a scanner in another. FDX-B is the transmission format within that standard — the way the chip sends its number when a reader asks. FDX stands for full duplex: the reader powers the chip and listens to its reply at the same time, which is why reads are effectively instant as your cat passes through a flap’s tunnel.

The chip itself is passive. It has no battery, holds no charge and does nothing at all until a reader — a vet’s handheld scanner, or the reader built into a SureFlap or PetSafe microchip flap — comes within a few centimetres and wakes it with a radio signal. The chip then transmits its number, and the moment passes. A chip implanted as a kitten can still be answering readers decades later, because there is nothing inside it to wear out or run down.

Why 15 digits

The 15-digit structure is the ISO standard’s identification code. The opening digits identify the country or the manufacturer the chip was issued under, and the remaining digits are the animal’s individual number within that series. The full sequence is unique to your pet: no other animal carries the same number, which is precisely what makes it usable as a key. Your flap does not read “a cat” or “a chip” — it reads one exact 15-digit sequence and compares it against the list of numbers you registered on pairing day. Match, and the lock releases; anything else, and the door stays shut.

This is also why the number matters beyond the flap. When a lost cat is handed to a vet or a shelter anywhere, the scanner reads the same 15 digits, and the registry record attached to that number is how the cat finds its way home. The chip holds only the number — your name, phone and address live in the registration database your vet records it in, not on the chip itself. Keep that registration current when you move or change numbers; the chip can only ever speak its digits.

The FDX-B pet microchip UAE picture

Vets across the UAE implant ISO FDX-B chips as the standard identification for cats and dogs, so the chip your pet almost certainly already has is exactly the chip our microchip flaps are built to read. If you adopted from a shelter, the paperwork will usually record the chip number — count the digits, and a 15-digit number beginning with the standard prefixes is the FDX-B format described here. If your pet has no chip, or an older one you are unsure about, any vet can scan and confirm the number and format in seconds, and implant an ISO chip in a single short visit if one is needed.

A note on older and foreign chips: pets arriving from abroad occasionally carry chips to an older standard, most notably the 10-digit FDX-A format once common in North America. Many modern readers — including the flaps we fit — are built around the ISO standard, so an older non-ISO chip may not be read reliably. The fix is simple and your vet will suggest it: a second, ISO FDX-B chip can be implanted alongside the first, and the flap is paired to the new number. Two chips cause no confusion at the door, because the flap only ever acts on the number you registered.

What your flap reads — and what it never sees

It is worth being precise about the privacy of the system, because owners occasionally worry the door is collecting something. It is not. When your cat pushes its head into the tunnel, the reader wakes the chip, receives 15 digits, checks them against a list stored in the flap, and opens or stays shut. No location is recorded, no journey is logged by the chip, and the chip cannot be tracked at a distance — it has no power of its own and answers only a reader a few centimetres away. The number is an identity, nothing more: a collar tag your cat can never lose, written in a format doors can read.

For cats over 4 kg, remember the size rule still applies alongside the electronics: a bigger cat needs a Large flap, microchip models included, so the door it unlocks is one its body fits through comfortably.

Frequently asked questions

How do I find out my pet’s chip number?

Ask your vet to scan your pet — the reader displays the 15-digit number immediately, and it will also be on your pet’s vaccination or adoption records in most cases. Keep a note of it in your phone; it is the number every scanner, shelter and flap will ever ask about.

Does the chip store my contact details?

No. The chip stores only its own 15-digit identification number. Your contact details are held in the registration database against that number, which is why updating the registry when you move house or change phone numbers is what actually keeps a lost pet traceable.

Can a chip be read from across the room or tracked like GPS?

No. The chip is passive — it has no battery and transmits nothing until a reader is within a few centimetres and powers it. It cannot be tracked, followed or read at distance. A flap reads it only when your cat’s head is in the tunnel.

My cat was chipped years ago abroad. Will your flaps read it?

If it is an ISO FDX-B chip — the 15-digit standard — yes. If it is an older 10-digit format, it may not read reliably, and your vet can add an ISO chip alongside it and pair the flap to the new number. A quick vet scan before fitting day settles which case you are in.

Does the chip ever need replacing or recharging?

No. With no battery and no moving parts, there is nothing to recharge or service. Chips very occasionally migrate within the body or, rarely, fail — both are things your vet can confirm with a scan, and a failed chip is simply replaced with a new implantation and a new number to register.

Will my cat’s chip work with a cat flap?

Yes, if it is the standard 15-digit ISO FDX-B chip that UAE vets implant — that is the number a microchip flap reads. If your cat was chipped abroad with an older 10-digit format, it may not read reliably — a quick vet scan settles which case you are in, or send us the chip number and we will confirm the right microchip flap.

Check the chip, then choose the flap

WhatsApp us on +971 52 443 2655 with your pet’s chip number or a note of its format, and we will confirm the right microchip flap for it — every FDX-B pet microchip UAE clinics implant is the format our flaps are built to read. You can also email admin@petdoorfix.com. We fit microchip cat flaps across all seven UAE emirates.

Next guide: Microchip Flaps for Multi-Cat Homes: Registering Every Cat on One Flap