Microchipping Your Pet: Legal Requirements & What You Need to Know

A microchip is a tiny transponder — roughly the size of a grain of rice — implanted under your pet's skin between the shoulder blades. It contains a unique identification number that links to your contact details in a national database.

When a scanner passes over the chip, it emits a low-frequency radio signal that powers the chip and reads the number. Every vet practice, rescue centre, and dog warden has a scanner. There is no battery — the chip is passive and lasts your pet's entire lifetime.

"Collars fall off. Tags wear away. A microchip is the one form of identification that stays with your pet permanently. I've reunited hundreds of lost pets with their families thanks to microchips — and had to euthanise unclaimed strays without one." — Dr. Sarah Chen, DVM

Microchipping should be on your new puppy checklist and new kitten checklist before anything else.

United Kingdom

• Dogs: Compulsory since 2016. All dogs must be microchipped by 8 weeks of age. Owners can be fined up to £500 for non-compliance
• Cats: Compulsory in England since June 2024. Cats must be chipped by 20 weeks of age. Scotland, Wales, and Northern Ireland are expected to follow
• The chip must be registered on an approved database (e.g., Petlog, IdENTICHIP)

United States

• No federal law requiring microchipping
• Many states and counties require microchipping for adopted animals from shelters
• Some municipalities require registration; check your local ordinances
• Major databases: HomeAgain, AKC Reunite, 24PetWatch

Regardless of legal requirements, microchipping is strongly recommended for all pets — indoor cats included. An open door, a broken screen, or a natural disaster can separate any pet from home.

Microchipping is quick, safe, and requires no anaesthesia:

• A sterile, pre-loaded needle injects the chip under the skin between the shoulder blades
• The sensation is similar to a standard vaccination — a brief pinch
• The entire procedure takes under 30 seconds
• No stitches, no recovery time, no sedation needed
• Many vets chip puppies at their first vaccination appointment

Cost

• UK: £10–£30 (often included in puppy/kitten vaccination packages)
• US: $25–$60 at a vet clinic; many shelters chip for free or at reduced cost

Some owners choose to have their pet chipped during spaying/neutering surgery, but there's no medical reason to wait. The earlier the better — lost puppies and kittens are harder to reunite without a chip.

Here's the uncomfortable truth: a microchip is only useful if the database has your current contact details. Studies show that up to 40% of microchipped pets have outdated or incorrect information — making the chip essentially useless.

Update Your Details When You

• Move house
• Change phone number
• Change email address
• Transfer ownership of the pet (e.g., rehoming)

How to Update

• Find which database your pet is registered on (your vet can scan and tell you)
• Contact the database directly — most allow online updates
• Some databases charge a small transfer fee (£6–£15)
• Register with a free lookup service like Check-a-Chip (UK) to verify your details are accessible

Pro tip: Set an annual reminder to verify your microchip details are current — do it when you renew your pet insurance or at their annual vet check.

• "It's a GPS tracker." — No. Microchips have no battery and no tracking capability. They only transmit a number when scanned at close range. GPS trackers are separate collar-based devices
• "It hurts." — The needle is slightly larger than a vaccination needle. Most pets barely react. No anaesthesia is needed
• "Chips migrate and cause cancer." — Migration is rare (2–3% of cases, and only by a few centimetres). Cancer at the implant site is documented in a tiny number of cases in the veterinary literature — the risk is considered negligible compared to the benefit of identification
• "Indoor cats don't need one." — Indoor cats escape. Doors get left open, windows break in storms, and emergencies require evacuation. A microchip is permanent insurance
• "My pet already wears a collar with a tag." — Collars can break, slip off, or be removed. A microchip is a permanent backup that can't be lost

Microchipping is a one-time investment that lasts your pet's entire life. Combined with a collar and ID tag, it gives your pet the best possible chance of coming home if they're ever lost. For more on keeping your pet safe, see our first aid guide.