What’s That Little Chip in My Cat’s Neck? Unraveling the Mystery of Pet Microchips

What is a Cat Transponder?

A cat transponder, also known as a microchip, is a small electronic device that is implanted under the skin typically between the shoulder blades of a cat. The transponder is about the size of a grain of rice and contains a unique identification number (VCA Animal Hospitals).

The transponder itself does not have a battery or tracking capabilities. It is passive, meaning it is inactive until scanned by a special microchip scanner. When the scanner is passed over the area where the microchip is located, it activates the microchip which then transmits the ID number. This number can then be used to identify the cat by cross-referencing it with a database that contains the cat’s information and the owner’s contact details (Progressive).

Microchips are a form of transponder technology that is specifically designed for animal identification. The terms microchip and transponder are often used interchangeably when referring to pet ID, as microchips rely on transponder technology to operate (VCA Animal Hospitals).

Common Brands and Types

Some of the most common pet microchip brands in the United States include HomeAgain, 24PetWatch, AKC Reunite, Avid, Bayer, and PetLink. These brands offer implantable transponders that operate at either 125 kHz or 128 kHz frequencies.

125 kHz transponders, such as those from Avid and HomeAgain, have shorter read ranges but can store more data. 128 kHz transponders, like the AKC Reunite and Bayer microchips, have longer read ranges and faster data transfer rates but less storage capacity. Both frequencies comply with ISO 11784/11785 global standards for animal identification.

Pet microchips sold in the U.S. must be Federally Communications Commission (FCC) approved. Popular 125 kHz models include the Avid MUSICC, HomeAgain Classic, and Datamars SECURE. Common 128 kHz options are the AKC Reunite Microchip and Bayer ResQ.

Implantation Process

Only licensed veterinarians are authorized to implant microchips in cats. This ensures the procedure is done properly and safely by someone with medical training.

The microchip is typically implanted under the skin at the back of the cat’s neck, between the shoulder blades. This area provides enough loose skin to implant the chip easily. The neck is also a universal location that animal control and vets know to scan for a microchip.

The implantation procedure involves these basic steps:

  • The vet scans the cat first to ensure no chip is already implanted.
  • A special implanter syringe is loaded with the microchip capsule.
  • The implanter needle is inserted under the loose skin between the shoulders.
  • The vet pushes the plunger to deposit the chip in the tissue.
  • The empty syringe is removed.
  • The vet confirms the chip is scanning properly.
  • The chip ID number is registered along with the cat’s information.

The process is quick, taking just a few minutes. The cat will feel only a slight prick from the needle, similar to a routine vaccination. Proper implantation ensures the microchip stays in place safely.

Reading a Transponder

A transponder is read using a handheld RFID scanner. There are many affordable options for pet microchip scanners available from retailers like Amazon, such as the RFID Chip Reader Scanner (https://www.amazon.com/Microchip-Recognition-Microchips-Transponders-Cushioned/dp/B07HNYGXQ1).

To scan a cat, simply hold the scanner around 2 inches away from the area between the cat’s shoulder blades where the microchip is implanted. Slowly move the scanner back and forth until you hear a beep, indicating the microchip has been detected. The scanner will display the unique ID number encoded in the microchip if there is a match.

The ID number can then be used to look up the cat’s registration information in a microchip registry database. This will provide the cat owner’s contact information, enabling the cat to be reunited with its owner if lost. Some scanners have the ability to check registry databases directly. The microchip itself only contains the ID number, no owner information. So reading the microchip provides the key to accessing the registration data.


After a cat is implanted with a microchip transponder, there are some maintenance considerations to ensure it continues working properly. The battery within the transponder lasts for many years, typically over 25 years according to the American Veterinary Medical Association1. However, the battery will eventually die, rendering the microchip useless. Pet owners can check if their cat’s transponder is still functioning by having their veterinarian scan it during annual wellness exams. If the microchip is no longer working, a new one can be implanted.

It is also essential for pet owners to keep their contact information updated in the microchip registration database2. If a lost pet turns up at an animal shelter, the shelter will scan the microchip to get the owner’s information and notify them. But if the contact info is outdated, the owner may never be reached. Pet owners should confirm their details are current whenever their address, phone number or email changes. Proper maintenance of a cat’s microchip transponder maximizes the chances of being reunited if a pet becomes lost.

1 https://www.avma.org/resources-tools/pet-owners/petcare/microchips-reunite-pets-families/microchipping-faq

2 https://www.humanesociety.org/resources/how-microchip-can-keep-you-and-your-pet-together


The average cost of a cat transponder (also called a microchip) ranges from $25-50 depending on your geographical location and veterinarian fees. The microchip itself is relatively inexpensive, usually $5-15. The bulk of the cost goes towards the implantation procedure done by a vet or clinic.

According the the American Veterinary Medical Association (AVMA), the average cost of implanting a microchip is around $45. This covers the microchip device, implantation by a veterinarian, and registration of your information into a pet recovery database. Additional fees may apply for any medication or anesthesia needed to keep your cat calm during the brief implantation procedure.

There may also be a small annual fee ($15-20 on average) to keep your registration information current in the recovery database. Most companies offer the first year of registration included with the implantation cost. Overall, microchipping a cat is an inexpensive way to greatly improve the chances of being reunited if your cat ever becomes lost.

Pros and Cons

Microchipping cats has many benefits compared to other forms of identification like collars and tags. According to Should I Microchip My Cat? Why a Microchip Is Important for …, microchips are permanent, can’t fall off, and provide proof of ownership. Unlike collars, a microchip can’t be removed if a cat gets lost. Microchips also store your contact information in a central database, allowing shelters and vets to identify a lost cat.

However, there are some risks to consider. According to Pros and Cons of Pet Microchips and GPS, the microchip implantation process poses a small risk of infection or migration under the skin. Some animal advocates argue microchips can cause cancer, but research has not found a causal link. It’s also important to keep your contact information updated in the microchip registry database.

Overall, most vets agree the benefits outweigh the small risks. Microchipping greatly improves the chances of being reunited with a lost cat.


Many countries and local jurisdictions have laws requiring pet cats to be implanted with microchips for identification purposes. For example, the United Kingdom passed legislation in 2021 making it compulsory for all cats over 8 weeks old to be microchipped and registered with an approved database.

In the United States, there are no federal laws mandating microchipping for pet cats, but some states and municipalities have enacted their own regulations. For instance, Los Angeles County requires all cats over 4 months old to be microchipped.

Microchips can facilitate travel with pets and access to pet-friendly housing. Many airlines require proof of microchip identification for cats traveling in-cabin. Additionally, landlords and property managers of apartment buildings, condominiums, and planned communities may mandate microchipping as part of their pet policies.

While regulations vary, transponders help provide permanent identification for cats and enable their return if lost. Keeping registration information up-to-date is crucial for reuniting lost pets with owners. Consult your local animal services agency or veterinarian to learn about microchipping requirements in your jurisdiction.


While microchip transponders are a popular choice for pet identification, there are some alternatives that may be better options in certain situations:

Tattoos have been used to identify pets for decades. The tattoo is applied to the inside of a pet’s ear or inner thigh using a tattoo machine and ink. Tattoos are permanent, but can fade or blur over time. They require shaving the area and holding the pet still during application, which some find stressful. Tattoos can only display a series of numbers and letters, not other data like microchips can. They must be manually checked by scanning the tattooed numbers to identify the pet [1].

Collars with ID tags are a simple, low-cost option for pet ID. Tags can display owner contact information and pet names visibly. However, tags can fall off or get removed. They also only work if your pet is found by someone who can contact you based on the tag.

Microchips may not be the best option for pets who are highly anxious, aggressive, or difficult to handle during procedures like implantation. Owners should consider if their pet can tolerate the insertion process without trauma when choosing an ID method.

For working animals like military or police dogs, brands like BackAgain offer rugged, tamper-proof microchip alternatives designed for field conditions [2].

Ultimately there are pros and cons to each type of pet ID that owners should research to find what works best for their needs.

Importance of Registration

It is critical to register your cat’s microchip information in a database after implantation. As the AVMA explains, “having the microchip placed is only the first step, and the microchip must be registered in order to give you the best chances of getting your pet back if it becomes lost.” 1

Registration connects the unique identification number on the microchip with your contact information. That way, if your lost cat ends up at an animal shelter or vet clinic, they can scan the chip to get your details and contact you. Without registration, the microchip is useless for reuniting pets and owners.

According to World Pet Net, registration enables “instant identification of the animal and its owner, helping them reunite faster.” When choosing a microchip brand, make sure it comes with free lifetime registration to maximize your chances of recovering your cat if it ever becomes lost. Maintaining up-to-date contact info in the registry is also essential.

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