How Pet Microchipping Works and What to Expect at the Appointment

A microchip cannot show you where your pet is. Many owners picture a tracking device, but pet microchipping does something simpler and longer lasting: it places an ID number under the skin that a shelter or veterinary team can read with a scanner when your dog or cat cannot tell anyone where home is.

That number matters most on the day a gate is left open or a door does not latch. The American Veterinary Medical Association (AVMA) reports that in one shelter study, microchipped dogs were returned to their owners 52.2 percent of the time, compared with 21.9 percent for dogs without a chip.

Quick Takeaway

• Primary insight: A pet microchip is a passive radio-frequency ID tag, not a GPS tracker. A scanner reads its number, and a registry links that number to your phone and address.
• Key fact: In a study of animals entering 53 shelters, the AVMA reports that microchipped cats went home 38.5 percent of the time, compared with 1.8 percent of cats without a chip.
• Best suited for: Fresno and Clovis owners of dogs and cats, including indoor cats and newly adopted pets, who want identification that cannot fall off.

What a Pet Microchip Is and What It Is Not

A pet microchip is a radio-frequency identification (RFID) transponder about the size of a large grain of rice that stores one thing: a unique ID number. The AVMA states that the chip has no battery, stays inactive until a compatible scanner passes over it, and is powered by the scanner's radio waves. Your name, address and your pet's medical history are not stored on the chip.

Owners often ask how a chip compares with a tag or a GPS collar. Each tool does a different job, and they work best together.

A chip does not replace a collar. The AVMA is direct on this point: nothing replaces a collar with up-to-date identification tags, and a rabies tag on the collar also shows vaccination status.

How Pet Microchipping Works When a Lost Pet Is Scanned

Pet microchipping works in three steps: a scanner reads the chip number, a lookup identifies which registry holds that number, and the registry supplies the owner's contact details so the finder can call. Shelters, animal control agencies and veterinary clinics scan found animals as one of the first things they do, according to the AVMA.

Chip standards explain why the type of chip and scanner matter. The World Small Animal Veterinary Association (WSAVA) describes the global standards, ISO 11784 and 11785, under which a compliant microchip carries a 15-digit numeric ID code and operates at 134.2 kHz. The AVMA notes that chips in the United States may operate at 134.2 kHz, 125 kHz or, less commonly, 128 kHz, with numbers that are typically 9, 10 or 15 digits long.

Universal scanners close that gap. A universal scanner detects all microchip frequencies, while a scanner that reads a single frequency can miss a chip made for a different one.

The lookup step runs through a tool many owners have never heard of. The American Animal Hospital Association (AAHA) runs the AAHA Universal Pet Microchip Lookup, now labeled the Microchip Registry Lookup Tool, which tells the person holding the scanner which registry to contact. AAHA does not keep its own microchip database, the tool does not display owner information, and it searches only the registries that choose to participate. Every step after the scan therefore depends on your microchip registration being complete and up to date.

What Happens During a Microchipping Appointment

A microchipping appointment takes minutes: the chip is placed with a needle, much like a vaccine, and no surgery or anesthesia is required. The AVMA describes a preloaded syringe with a sterile needle that places the chip just beneath the skin, typically between the shoulder blades, and says the process is no more painful than a typical injection even though the needle is slightly larger.

At Riverpark Pet Hospital, microchipping is a quick, no-anesthesia injection that is usually done during a wellness visit or while a pet is already being spayed or neutered. Our team also helps you get the chip activated and registered to your contact details. A puppy or kitten visit is a natural time to add one.

Three steps make the visit more useful:

• Before the visit: Tell the team if your pet was adopted, since a shelter or rescue may have already placed a chip.
• During the visit: Ask to see the scanner read the new chip so the number matches your paperwork.
• Every year: Ask for a scan at your pet's wellness exam to confirm the chip still reads.

What the Research Says About Microchips and Reunions

Research on shelter animals shows that microchipped pets go home far more often than pets without chips. The most cited work is a 2009 study in the Journal of the American Veterinary Medical Association by Lord and colleagues at The Ohio State University, which followed 7,704 microchipped animals entering 53 animal shelters between August 2007 and March 2008.

The AVMA summarizes the return-to-owner results from that study this way:

Microchipped dogs were returned more than twice as often, and microchipped cats more than 20 times as often.

The same study shows where chips fall short. Among 876 animals whose owners could not be found, the leading reason was an incorrect or disconnected phone number (35.4 percent), followed by owners who did not respond to calls or a letter (24.3 percent). When shelters contacted a registry, only 58.1 percent of the chips were registered at all. The implant is half of the job; the registry record is the rest.

How Safe Microchips Are for Dogs and Cats

Microchips have a strong safety record, and serious problems are uncommon. According to the AVMA's microchipping FAQ, the most frequently reported issue is migration, in which the chip moves from the spot where it was placed. Other uncommon complications include chip failure, hair loss, infection or swelling at the site.

Tumor risk is the concern owners raise most. The AVMA states that tumors associated with microchips have been reported but are rare, and that a cause-and-effect relationship has not been established in dogs and cats. No medical procedure is free of risk, so tell your veterinarian about any lump, swelling or soreness near the shoulder blades after a chip is placed.

Why Cat Microchipping Matters Even for Indoor Cats

Cat microchipping matters for indoor cats because a cat that slips outside is usually not wearing a collar and is rarely returned without identification. In the shelter data above, only 1.8 percent of cats without a chip went home.

Feline specialists recommend identification regardless of lifestyle. The American Association of Feline Practitioners states that microchips offer the most reliable method of reuniting cats separated from their owners or caregivers, and it advises that scanning to verify the chip works be part of any veterinary visit.

What California Law Says About Microchipping Dogs and Cats

California law requires shelters and rescue groups to make sure a dog or cat is microchipped before the animal leaves their care. Under Food and Agricultural Code section 31108.3 for dogs and section 31752.1 for cats, a public animal control agency or shelter, SPCA or humane society shelter, or rescue group may not release an animal to an owner reclaiming it, or adopt out, sell or give away an animal to a new owner, unless one of two conditions is met:

• Chipped and registered to you: The animal is microchipped with current information, and the owner or new owner is registered with the microchip registry as the primary owner. The shelter or rescue may not be listed as the primary owner.
• A 30-day agreement: If the shelter or rescue cannot microchip on site, the owner signs an agreement to show proof of microchipping within the next 30 days.

Both statutes include exceptions. A chip is not required when a licensed veterinarian certifies in writing that the animal is medically unfit for the procedure, or when the owner signs a form stating that the cost would be an economic hardship. An agency that violates either section is subject to a civil penalty of $100.

Sections 31108.3 and 31752.1 regulate shelters and rescue groups; neither one, on its own, requires an owner who got a pet elsewhere to have it chipped. Cities and counties can set their own rules, so check with your local animal services agency.

One Short Visit Gives Your Pet an ID That Stays Put

A chip the size of a grain of rice turns a frightened stray with no name into a pet with a phone number attached, as long as the registry record behind it is accurate. Pet microchipping takes seconds and keeps working for years.

Riverpark Pet Hospital places microchips during wellness visits and spay or neuter procedures for families across Fresno and Clovis, helps you activate the registration, and will scan any found pet you bring in at no charge. Request an appointment online or call (559) 712-7387 to add a microchip to your pet's next visit.