Published by: Ingrid King. Last Updated on: January 25, 2023 by Crystal Uys


Cats need some form of identification, regardless of whether they’re indoor or indoor/outdoor cats. Even indoor cats can slip out the door and get lots, and wearing identification, whether it’s a collar and tag, or a microchip, can increase the chances of a lost cat being returned to its home.

A microchip is a small, electronic chip enclosed in a glass cylinder that is about the size of a grain of rice. The chip has a unique identifier which can be read by a scanner.

While most veterinarians and cat experts recommend microchips for all cats, there have been some recent concerns about microchips causing cancer. This article addresses the benefits and risks of microchips for your cat.

How microchips work

Microchips are implanted under the cat’s skin between the shoulders, using a hypodermic needle. The needle is slightly larger than a normal syringe, but the injection itself causes very little pain, and cats won’t require sedation for the procedure, which only takes a few seconds.

A microchip contains a unique id number, which is registered in a database. If a stray cat is turned in to a shelter or veterinary clinic, the cat will be scanned for a microchip. If the cat is chipped, the unique id can be traced back to the cat’s original owner.

You must register your cat’s microchip

Microchips only work if the cat’s guardian has registered the microchip. Once the cat is microchipped, guardians can register the chip id with the chip’s manufacturer. Some veterinary clinics will take care of the registration for you. There may be a small fee associated with registration.

Keeping your contact information updated with the microchip database is critical in the event that your cat gets lost. Outdated contact information is the most common reason why found cats can’t be reunited with their owners.

Problems with microchips

There are a number of potential problems with microchips. Chips can fail. Chips can also migrate, which means that they may move under the skin from the original location between the shoulder blades. Typically, migrating chips may move down the cat’s leg. This is not going to be painful for the cat, but if the cat gets lost, the shelter or clinic scanning for a chip may not discover it.

The biggest problem with microchips is that cat guardians don’t keep their contact information updated. Some microchip companies may charge a small fee each time you update your contact information, but that fee is well worth the peace of mind.

veterinarian doctor holds cat
Image Credit: H_Ko, Shutterstock

Do microchips cause cancer?

There have been a few articles circulating that link microchips to cancer in pets. It is important to understand that ANY injection has the potential to cause cancer in cats. These injection-site cancers are called fibrosarcomas. They are most often associated with inactive killed rabies or feline leukemia vaccines, or with multiple vaccines given at the same time, but they can also be caused by other injections such as steroids. The risk of a microchip causing cancer is most likely low, but we don’t really have enough data yet to know for sure.

To microchip or not?

Although there is no guarantee that every shelter or veterinary clinic will always be able to read every chip, with the availability of universal scanners that can scan all manufacturer’s chips, and with increased awareness about the potential of chips to migrate, microchips are still the best way to increase the chances that a lost cat will be returned to his home.

If you have concerns about microchips, discuss them with your cat’s veterinarian. For most cat guardians, the benefits of microchips will outweigh any potential risks.

Allegra and Ruby are both microchipped, even though they never go outside.

Are your cats microchipped?

This article was previously published on and is republished with permission.

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