A microchip that's registered to the wrong number is worse than no microchip at all — because you think you're covered, and you aren't.
It's one of the most common support requests we get, and almost nobody finds out until the worst possible moment. Your dog is scanned at a vet, the number comes up, and it doesn't match anything on file. Here's how to check yours in about two minutes, and what to do if it's wrong.
First, what a microchip actually is
A microchip is a small device, about the size of a grain of rice, holding a 15-digit number. That number is the whole thing. It isn't a tracker, it has no battery, and it can't tell anyone where your pet is. What it does is link back to your contact details on a microchip database — for MyPet chips, that's the MyPet Database.
Because there's no power source, a chip can't fail quietly the way a battery-powered tag can. Any scanner can read it, and every vet, animal rescue and local council in the UK has one. That's the good news.
The bad news is that the chip is only half the system. The other half is whether the number in your pet matches the number on the record — and that's the half nobody checks.
Why the number on file can be wrong
When a number doesn't match, it's rarely anything dramatic. In our experience it comes down to one of three things:
- A mix-up by the breeder or implanter at the time a litter was chipped — puppies and kittens get chipped in batches, and two records get swapped.
- A paperwork mix-up between animals after chipping, usually when records are transcribed by hand.
- A single digit written down wrong. Fifteen digits is a lot of digits.
None of these are visible from the outside. The pet is chipped, the certificate looks right, and everything appears to be in order until someone scans them.
How to check your pet's microchip
You don't need to book a special appointment for this, and you shouldn't pay for one. Do it at the next appointment your pet already has.
- At your pet's next visit — a vaccination, a check-up, anything — ask your vet to scan the microchip and read you the number. It takes seconds and practices are used to the request. Show them this article if it's easier.
- Find your registration certificate. If you're with MyPet you can download a fresh copy from your account any time.
- Compare the two numbers, digit by digit. All fifteen. It's the last few that usually catch people out.
- While you're there, check the details attached to that number are still yours — the phone you actually answer, and an address you actually live at.
That last step matters more than people expect. A correct chip number pointing at a phone you stopped using in 2019 fails in exactly the same way as a wrong number.
What to do if the number is wrong
Tell us and we'll fix it — you don't need to work out whose mistake it was, and there's no charge for correcting it. Open a support ticket with the number your vet read out, and our team takes it from there.
If your pet is on a premium plan you'll hear back within 24 hours. On MyPet Basic it can take up to five working days — the fix is the same either way, it just sits in a different queue.
How often should you check?
Once a year is plenty, and tying it to an appointment you're already attending makes it free and roughly effortless. If your pet has a MyPet microchip — the number starts 956 — you've got one of the better chips on the market in there, but the number still wants checking, because the failure we're describing happens on paper, not in the chip.
Two other moments worth a check: when you take on a pet from someone else, and after any change of vet practice. Both are points where records get re-entered by hand.
Where the plans come in
Checking and correcting your microchip number is free, on every plan, and always will be. So is keeping your details up to date and transferring your pet to a new owner. MyPet Protected and MyPet Pampered add the lost-pet tools on top — faster support, alerts when the chip is scanned, and the Smart Pet Tag.
The short version
A microchip is a fifteen-digit number and a promise that the number leads back to you. The chip end of that almost never breaks. Check the other end once a year, and you've done the single most useful thing available to get your pet home.
— Conor
Written May 2025, reviewed August 2026. In 2024 we helped reunite over 1,000 missing pets with their owners through their microchip. Lost pet right now? Our reunification line is free to call, 24/7: 0800 368 4150.
