Does Your Pet Have the Right Microchip for International Travel?

What Is an ISO Microchip? (ISO 11784 and ISO 11785 Explained)

When authorities at a border crossing scan your pet's microchip, they're not just looking for any chip — they're looking for one that meets a specific international standard.

ISO 11784 defines the data format: how the chip's unique identification number is structured and stored. ISO 11785 defines the reading protocol: how a scanner communicates with the chip to retrieve that data. Together, these two standards ensure that a chip implanted in the UK can be read by a scanner in France, Spain, Australia, or anywhere else that participates in international pet travel.

The clearest sign of ISO compliance is the chip number itself: ISO-compliant microchips produce a 15-digit number, which typically begins with a country code (985 for the UK) or a manufacturer code. This number is what gets recorded on your pet's health certificate or pet passport — and it's what border officials will check against their scanner.

Countries require ISO compliance for a straightforward reason: without a shared standard, a chip implanted in one country might be completely invisible to a reader in another. ISO ensures the system works reliably across borders.

ISO vs Non-ISO Chips — What's the Difference?

Not all microchips are created equal, and the difference matters when you're crossing an international border.

FDXB chips (Full Duplex B) are ISO-compliant and operate at 134.2 kHz. They're the standard used across the UK, EU, and most of the world. If your pet was microchipped by a UK vet in recent years, they almost certainly have an FDXB chip — which is reassuring news for most readers.

FECAVA and EMID chips are older, non-ISO formats that operate at 125 kHz. These were more commonly used in the United States and are sometimes found in rescue animals or pets imported from abroad. An ISO scanner won't pick them up — which is precisely why they cause problems at borders.

A few things worth knowing:

• Most UK pets are already compliant. FDXB chips have been the UK standard for many years, so the majority of domestic cats and dogs are fine.

• Rescue and imported pets are higher risk. Animals rehomed from overseas charities or imported from the US may carry non-ISO chips.

• US scanners don't always work in reverse. Some older American chip readers can't detect ISO chips either — worth knowing if you're importing a pet from the States and relying on US veterinary records.

How to Check If Your Pet's Microchip Is ISO-Compliant

The good news: checking ISO compliance is straightforward. Here's what to do:

• Look at the chip number. ISO-compliant chips have a 15-digit number. If your pet's chip number is 9 or 10 digits, it's likely a non-ISO format.

• Ask your vet to scan with a universal reader. ISO-compatible (universal) scanners can detect both FDXB and older chip types. This is the most reliable way to confirm what type of chip your pet has.

• Check your microchip database record. Your pet's chip should be registered on a UK-approved database. Log in and confirm the number matches what's on your veterinary records.

• Cross-reference with your pet's paperwork. Vaccination certificates, vet records, and any existing travel documents should all show the same 15-digit number.

If you're unsure after checking, your vet can tell you definitively — it's a quick question and worth asking before you get any further into the travel documentation process.

What If My Pet's Chip Isn't ISO-Compliant?

First: don't panic. This is a solvable problem — it just needs to be addressed at the right time.

Re-chipping is the standard solution. A new ISO-compliant FDXB chip is implanted alongside the existing one — the old chip is not removed. Both chips are then recorded on your pet's documents, with the new ISO chip number used as the primary identifier for travel purposes.

A few important points:

• The old chip number should still be recorded on all veterinary records to maintain continuity of your pet's history.

• Timing is critical. For travel to destinations that require a rabies vaccination, re-chipping must happen before the rabies jab. If the vaccination is given first and the chip number later changes, the vaccination record may be considered invalid.

• This can affect your overall timeline. Re-chipping followed by a new rabies vaccination — and then the required waiting period in some cases — can add weeks to your travel preparation.

The earlier you identify a non-compliant chip, the more breathing room you have. If there's any doubt, get it checked at your very next vet appointment.

Why Your Microchip Matters for Your Pet Travel Certificate

The microchip number isn't just a registration detail — it's the thread that ties your entire pet travel documentation together.

When an accredited vet issues a health certificate (the document required for most international travel since the UK's departure from the EU pet passport scheme), the microchip number is recorded directly on that certificate. At the point of entry, a border official will scan your pet and check that the number on the chip matches the number on the document. If they don't match — or if the chip can't be read — your pet may be refused entry, held for additional checks, or in the worst cases, placed in quarantine.

An accredited vet plays a key role here: they physically scan the chip before completing any travel documentation, confirming the chip is readable and the number is correct. This is part of why using a qualified professional matters, rather than relying solely on self-reporting from older records.

A non-compliant or unreadable chip isn't a minor admin issue — it's a potential barrier to entry. Getting this right before everything else is the smartest thing a pet owner can do.

Frequently Asked Questions

My pet was microchipped in the US — will their chip work in Europe?

Possibly, but not always. Many US-microchipped pets have non-ISO chips (FECAVA or EMID format) that won't be detected by standard European scanners. If your pet was chipped in the US, ask your vet to scan them with a universal reader and check the chip number. If it's not 15 digits and ISO-compliant, you'll need to have them re-chipped before travel.

Can I travel with my pet if they have two microchips?

Yes — having two chips is not a problem in itself. What matters is that the ISO-compliant chip number is clearly recorded on all travel documentation, and that it's the one picked up when border officials scan your pet. Your vet should note both chip numbers on your records, with the ISO chip designated as the primary travel identifier.

Does the UK require an ISO microchip for pets travelling from abroad?

Yes. In line with guidance from the UK Government and APHA (Animal and Plant Health Agency), pets entering the UK must be identifiable by microchip, and that chip must be readable by an ISO-compatible scanner. The chip number must match the animal's travel documentation. Requirements can vary slightly depending on the country of origin, so always check the current APHA guidance for your specific route.