Microchip not scanning or can't be found? What to do (UK)

1. Ask for a full-body scan with a scanner that's working. The government only counts a chip as failed if it can't be found after a full-body scan with a working scanner, and suggests testing the scanner on another chip, or changing its batteries, if in doubt.
2. If the scanner finds a number, check it's registered, and in your name, on an approved database. A chip that reads but isn't registered doesn't count in law.
3. If nothing is found, ask your vet whether they can feel the chip under the skin, or see it on an X-ray or ultrasound. That tells you whether it has failed, moved or gone.
4. If it has failed or gone, have a new chip put in and register the new number. PDSA says the manufacturer will usually provide a replacement chip free of charge, and the vet can put it in alongside the old one. The government won't tell your database for you, so update it yourself.
5. Keep a tag on the collar meanwhile. Anyone who finds your pet can read a tag without a scanner.

In the UK, microchips for dogs and cats are implanted under the skin on the back of the neck, just in front of the shoulder blades, but a chip can move a long way from there. PDSA says it's much more common for a chip to move a small distance, which doesn't hurt, and that it will still be picked up when scanned. A chip that has moved further can be missed, though, which is why a full-body scan matters: a scanner passed only over the shoulders can miss a chip that has moved.

The best figures come from the government's Veterinary Medicines Directorate, which collects reports of microchip problems. From April 2014 to December 2015 it received 1,420 reports: 729 of a chip moving, 630 of a chip failing and 61 of a reaction. Most were about dogs.

Many of those weren't what they seemed. Of the 630 failure reports, the chip was confirmed to still be in the animal in only 56, so only those could truly be called failures; the rest may have moved or worked their way out through the skin. Where the date was known, failures were most often found three to four years after the chip went in, and the longest was seven years. Of the 729 migration reports, about 300 looked like real migrations.

The directorate couldn't work out a rate, because it doesn't know how many chips are sold, but with an estimated 8.5 million dogs and 7.5 million cats in the UK it concluded the chance of a problem is very low.

In England, a dog or cat only counts as microchipped when it has a chip that meets the standard and its details are recorded on an approved database (regulation 3 of the 2023 regulations). GOV.UK says you can be fined up to £500 if your pet isn't registered on one of the approved databases, and PDSA says that if a dog warden scans your dog and finds no microchip, you'll have 21 days to get them microchipped.

Use our microchip number checker and the list of approved databases to find where the number is. If it's still in a breeder's, rescue's or previous owner's name, follow our guide to transferring a microchip to a new owner. If your details are just out of date, see updating microchip details.

One database has been taken off the list: GOV.UK says Track Your Paws doesn't meet government standards, and that if your pet is registered with it, you should register with another approved database.

Some microchips can't be read by the scanners approved in the UK. The government's review says these aren't true failures, but a pet with one will need a new, compliant chip, because the law asks for a chip that meets the ISO 11784 and 11785 standards. Our guide to whether a phone can scan a microchip explains the standard.

Under regulation 11 of the Microchipping of Cats and Dogs (England) Regulations 2023, anyone who finds that a microchip implanted in a cat or dog has failed, or has moved from where it was put in, must report it to the Secretary of State. In practice your vet or the implanter does this, using the government's adverse event reporting form.

The government's review says it doesn't pass these reports on to the microchip databases, so updating your pet's record is down to you.

The time to find out a chip has failed is at a routine check-up, not when your pet is missing. Ask your vet to scan your pet at their annual check, and make sure the number they read matches your paperwork and your database record. If you don't know the number, Dogs Trust says you'll need to have your pet scanned at a vet.

A chip only helps once your pet reaches someone with a scanner. A collar tag, and for a dog the name and address the law asks for, works in the hands of whoever finds them, and a QR code tag lets them reach you straight from their phone. See where to get a microchip scanned if you've found a pet.