Microchipping Cats: Common Questions, Complications And Side Effects (There’s A PINCH Involved)

A microchip is essentially a small information chip, a radio frequency identification (RFID) device, that is inserted under your cat’s skin.

It’s fairly small, about the size of a grain of rice and transmits data to a special handheld device.

Note: An RFID chip does not produce any radio-frequencies, it absorbs energy from the devices that scan the chip and then emits the radio-frequency.

Your pet is not subjected to any radio waves if it has a chip. 

This chip contains an ID number with information about your cat (linking you and your cat together should they get lost/ your information will be on the chip).

This information can be as limited or as broad as you would like and is usually the information you share with your local vet.

identifying a cat with a microchip device

Such as:

  • Your cat’s name
  • Gender
  • Any markings that make your cat unique, whether they are spayed/neutered
  • Your contact information. 

I’ve done a bit more in-depth research into microchips for pets and I’d love to share.

First, a little story: 

About a year ago, when it was warm (and I was 6 months pregnant), I decided to leave the door of my house open (and all the windows) to get a breeze flowing. 

But that nice summer breeze wasn’t the only thing that made it’s way into my house that day – after a while, in wanders in this beautiful brown cat.

Want to know how I realized she was in the house?

I heard her eating my cats’ food! 

I caught a glimpse of something coming in the door and because we also have a brown-haired cat, I assumed it was her.

story time with a cat on a book

A few minutes went by and I heard something rustling under the couch…and my brown-haired fur baby appeared at my feet.

I turned, very slowly, to the cat bowl and saw her there munching on Whiskas seafood dinner like it was no big thing.

It would have been like a scene from a horror movie (like those ones where you realize there is a stranger in your house) – if she wasn’t so darn cute.

The fact that this cat was so calm (calm enough to wander into our home and help herself to some grub), I assumed she belonged to someone.

She had a collar but no ID tags. 

Long story short:

After some debate, we decided to take her to our vet to see if she had a microchip – and she did! 

The craziest part of this story is that she was from a town about half an hour (by car) away from us.

When we called the woman (whose telephone number we got from the information on the microchip), she was shocked.

Her family cat had been missing for almost two weeks.

When we brought the cat to her, I could see the tears and gratitude in her eyes and I almost teared up myself when her little daughter came running out of her office and hugged the cat. 

We will talk more below about different reasons to microchip your cat (or why some people decide against it) but all I can tell you is that this family was reunited with their beloved furry friend because they had her microchipped.

That’s pretty incredible.

She walked in like she owned the place.

What Does it Mean to Microchip a Cat?

As it turns out, it has become increasingly common in recent years for pet owners to place the equivalent of an ID tag in, rather than on their pets.

Like we said above, a microchip is a tiny computer chip the size of a grain of rice, and it’s placed underneath the animal’s skin. 

This microchip can then be accessed when a scanner or reader is passed over the area of the pet where it has been implanted.

If the animal is subsequently lost and ends up somewhere that uses such readers to identify pets (such as an animal shelter or a veterinarian’s office), then the pet can be identified and restored to its owner.

microchipped happy cat traveling home

Many shelters now microchip all incoming animals.


Australia has required the microchipping of all dogs and cats since 1999. The UK passed a similar law in 2016, ensuring all of the 106,000 dogs that are missing or stolen each year have a better chance of finding their home again. 

Gov.UK on Compulsory Dog Microchipping

Even though it’s compulsory in some places, there is a lot of confusion around microchipping your pets…so we’re here to set the record straight.

Here are two of the biggest misconceptions around pet microchips:

  1. No information about the owner can be read directly from the microchip.
    1. It doesn’t contain your name, address, phone number, etc., as a conventional ID tag on a collar typically would.
    2. Instead, the scanner reads an ID number from the microchip.
    3. The companies that manufacture these chips keep databases of the information people have submitted when registering their pet’s microchip.
    4. When a pet with a certain ID number has been found, the veterinarian, shelter control officer, etc. is authorized to access these databases online or by phone, so that the owner can be contacted.
  2. The microchip is not a tracking device, like a GPS tracker for cats. (How cool would that be, though?!)
    1. It does not enable the pet owner or another party to somehow identify a lost pet’s location.
    2. Someone with the appropriate kind of reader has to already be in possession of the animal and to pass the scanner over it in order to find out if the animal has a microchip and what its ID number is.

How Does a Cat Get a MicroChip – The Procedure

First, you have to get your cat to a vet! You can read more about Traveling with your cat here.

To microchip a cat, a veterinarian places a glass-encased microchip at the end of a syringe that is slightly bigger than those used for vaccinations.

The microchip is then injected underneath the skin, with the most common location being in the animal’s back, between its shoulder blades.

The injection takes just a few seconds and (as you can see in the video below) is relatively painless for your pet. 


The initial injection of it is a modest pinch that causes about the same amount of passing discomfort as a blood draw.

It is sometimes inserted under anesthetic and sometimes not. 

This will, of course, depend on the veterinarian’s preference, and also how tolerant the individual cat is of such procedures.

Some cats are fine and barely notice it, whereas some cats are traumatized the moment they realize they’re going to the vet, and will refuse to cooperate with anything done to them there (no matter how little it will hurt them).

What some pet owners do is schedule the implantation so that it takes place on the same visit as some other procedure that will require sedation, such as a teeth cleaning, or when their pet is being spayed or neutered.


Microchips aren’t just for cats and dogs! A microchip can be given to lots of different animals – horses, ferrets, and most other mammals are able to have them implanted as well! [1]

When Is the Best Time To Get My Cat MicroChipped?

A kitten can be microchipped as soon as it is stable and healthy enough. 

Although veterinarians tend to go more by size and stability rather than age, usually this can be as early as five weeks old. 

However, most veterinarians prefer to wait until it is no longer nursing and is at least eight weeks old (or over 2 lbs, whichever comes first). [2]

When you have your pet microchipped, a key part of the procedure is providing all the registration information for the database that will be searched if your pet gets lost and is found.

microchipping implant procedure on a cat

If your information is not associated with the microchip’s unique number in the database, then microchipping serves no purpose.

How Much Does Getting My Cat MicroChipped Cost?

The procedure costs less than most people would guess.

Figure $50 or so for the cost of the vet, and the fee to register your information to the chip in the database usually falls well below $20. 

You may be able to pay even less if you have the procedure done during an office visit you are having for other reasons anyway.

Also, a veterinarian at an animal shelter or rescue group in your area may charge less.

Some animal shelters or vet clinics microchip stray animals for free (if you bring in a stray from your area).

Plus, if you’re adopting your cat from a shelter, there’s a good chance it already has a microchip.

In my experience, it’s very worth it.

cat playing inside box home safe and microchipped

Microchipping Cats Pros And Cons: Drawbacks And Limitations

We all want what’s best for our animals – we want them to be happy, healthy and safe…so, is there any danger to microchipping your cats?

It’s actually very little in terms of side effects or physical risks to cat microchips, which are non-toxic.

There is always some risk of infection and related complications to any procedure that breaks the skin, including implantation of a microchip, but this risk is extremely low when you have the procedure done by a trained veterinarian.

(It is not legally mandated that microchips be implanted by a vet, but it is strongly recommended.)

There have been reports that in a minuscule number of cases microchipping has caused at least temporary paralysis.

Again, the already low likelihood of this is further reduced if the procedure is done by someone properly qualified to do it, i.e., someone who won’t botch the job by implanting the chip too close to the spine.

If you search online, you’ll find some concerns about the microchips causing cancer.

Do microchips in cats cause cancer?

The actual evidence for this is thin.

There is a very low risk of an animal eventually developing cancer around the site of a vaccination… if the implanting of a microchip can lead to cancer at all it appears to be even considerably lower than this.

There are a very few anecdotal cases of pets having developed cancer near where they had a microchip implanted, but it’s not certain it was caused by the microchip even in those cases.

Probably the most significant evidence is that studies using certain types of rats and mice have shown a higher incidence of cancer in those that were microchipped than in those that were not, but those animals do not have similar biological systems as cats.

And if somehow microchipping cats did carry a comparable cancer risk as microchipping these test rodents, then it would have shown up by now, given that microchipping of pets has existed for decades.


The microchips have been known to move from where they were implanted as the animal ages.

(You might be able to feel the chip through your pet’s skin, so you can check to see if it ever moves from its original location. Or you can always ask your vet to scan your cat and verify that the chip has not moved.)

This doesn’t cause the animal pain or cause health problems, but it can be an issue if someone scanning the pet only checks between the shoulder blades.

In fact, though, most professionals who would be using such a scanner understand that not a hundred percent of microchips are placed in that spot and that microchips can occasionally move, so they know to pass the scanner over the animal’s entire body.

How Are Microchips Made and How Do Microchips Work?

The microchips are manufactured by different companies (in the U.S., most are made by Avid or HomeAgain), and have different readers and different databases.

This means there is a chance your lost cat could have a microchip that cannot be read by the scanner used by, say, a shelter where it is turned in.

Or for that matter, perhaps your cat is turned into a shelter that doesn’t scan for microchips at all.

Here’s the thing…

As microchipping has become more common, this is rarely a problem any longer.

It is pretty much automatic now for shelters and veterinarians to check for microchips, and they almost all have either multiple types of scanners or more likely a universal scanner.

Microchips are designed to last 20 to 25 years, so they do not need to be replaced.

But there’s always some small chance a given chip will not last that long and will malfunction before that.


Of course, microchipping won’t help in a case where your cat wanders off to where it is not found at all. (Again, it’s not a GPS tracking device.)

It also is unlikely to help if your cat is stolen rather than lost. I say “unlikely” rather than “impossible,” though, because in fact in some cases it does help.

Veterinarians often learn of lost pets in their area through flyers or being told by the pet owners.

If someone brings in a cat for some kind of treatment, and the vet notices that it resembles a specific lost pet, a scan for a microchip might well reveal that the person currently in possession of the cat is not, in fact, the cat’s owner.

Related Questions:

How is a microchip inserted into my pet? A microchip is about the size of a piece of rice and it’s inserted into your pet by using a needle. Usually, this incision is made between your pet’s shoulder blades. 

Does it cause my pet any pain to have a microchip? No. Your pet will feel a bit of discomfort while getting the chip (depending on what kind of pet you have, this can vary) – but afterward, they will not feel a thing! 

Does my pet’s microchip need to be renewed or changed? Although your pet’s microchip should last throughout their whole lifetime, you will need to register the ID number and keep your contact information relevant. (More information on that below!)

 How much do microchips cost? We’ll go into more details about the costs below, but you should expect anywhere from $30-$50 for the microchip itself and a few extra dollars to register the chip in the database. Some animal shelters do this for free (or at a discounted rate) with the adoption of an animal. 

How is my pet’s microchip read? Most vet offices and animal shelters have an ID scanner that can read these microchips, however, you can also purchase an ID scanner online if you’re interested in having one. (that link will take you over to Amazon.)

Do all microchips emit the same frequency?

As new companies entered the micro­chip market, new frequencies as well as scanners were introduced. In 1996, the International Organization for Standardization (ISO) established 134.2 kHz as the standard frequency for microchips used in animals. [2]

Although ISO standards are being followed in most countries, including Canada, Europe, Asia, and Australia, [2] the United States does not follow these standards.

There­fore, US micro­chip manufacturers do not have to make only 134.2-kHz micro­chips.

As a result, three different frequen­cies — 125 kHz, 128 kHz, and 134.2 kHz — are used in this country.

In addition to the different frequencies, some of the micro­chips are encrypted.

In 2007, the USDA ruled that it did not have the authority to require manufacturers to follow ISO standards. [2]

According to the Coalition for Reuniting Pets and Their Families, fewer than 25% of lost pets in this country are reunited with their owners. [4]

However, in countries where ISO technology is used, the reunification rate is much higher. [4]

For example, in the United Kingdom, 47% of lost pets are reunited with their owners. [4]

Here is a little video on how microchips work and why you should have own for your pet: 


Why Do People Refuse to Microchip Their Pet? 

Ultimately, the choice to microchip your pet is yours. There are pros and cons, like with everything else.

Here are a few of the reasons some people may choose not to microchip their pets…

Religious Reasons

You might think I’m joking or making it up, but a few people have moral or even religious objections to microchipping pets.

In some cases, it’s a kind of “it’s not natural, and anything that’s not natural is bad” moral objection.

Then there are certain fundamentalist religious peoples who vehemently object to any high-tech identification scheme like this for humans (an example is comparing it to the “Mark of the Beast” which is warned about in the Bible), and a minority of those people extend that opposition to the microchipping of animals.

(Consider this example; a woman explains how her family refuses to microchip pets on religious grounds, and she then expresses concern that if she acts contrary to her family in this respect with her own pets she may be dooming them to Hell.)

checking for a microchip implant on a cat using a scanner

If you find any such moral or religious objections to microchipping persuasive, that’s a personal matter that is for you to decide.

Cost Of Microchipping A Cat

Some people just aren’t aware of how little it costs to have done (and have maybe never lost a pet, so don’t know if it’s worth it or not). 

Ultimately, you decide where you spend your money.

But as someone with 2 cats (one who has been lost for a week and one who I adopted from a shelter), I can tell you it is most certainly worth it if it means your pet will be returned to you easier and faster! 

Prices (like we talked about above) can range from $20-$50 for the actual microchip and then a few more dollars for the registration. 

Not Being Educated on Microchips (or Misinformation)

While there are a few reasons people do choose not to microchip their pets, ultimately the biggest problem lands with the pet owners.

A significant percentage of people who have their pet microchipped fail to keep their contact information in the manufacturer’s database updated.

So a stray cat might end up at a vet’s office or shelter, and a scan might reveal that it has a microchip of a certain type with a certain number, but if the owner contact information for that number is obsolete, the cat may never be reunited with its owner.

So if you do get your pet microchipped, remember that you have to keep that registration current.

How Do I Update/Register My Pet’s Microchip to Me? 

This makes all the difference!

Whether you’ve recently moved, had your information changed or have adopted an already-microchipped pet from your local shelter – keeping that microchip information up to date is key!


What good is a microchip if the information is wrong? 

The first way to do this is by visiting your local vet and telling them you need to update your pet’s microchip – this should be easy for them to do. 

OR Search Here for a Microchip Clinic Near You

Another way you can register your pet is by doing it yourself through an online registry (listed below): 

If you find a stray cat (or want to check what your pet’s current microchip information is) you can check out some of these sites: 


Some people prefer to have ID tags on their cat’s collar instead of a microchip – but collars can come off and ID tags can become unreadable over time. Which would you do – or would you do both?

Microchipping OR A Collar With Tags – Which is Better?

What’s the point, you might be thinking, of this futuristic, fancy schmancy technology, when the option of a simple tag worn on a collar already provides the owner contact information so that a lost pet can be returned?

On the one hand…

It could be argued that a tag is not only just as good as a microchip but better.

I mentioned above that by now most (but not all) shelters and such scan for microchips, and that they typically use multiple scanners or a universal scanner to be able to read different types.

But obviously, most ordinary citizens do not have these scanners.

So if your lost cat is taken in by someone a few blocks over from you, they most likely aren’t going to scan the animal for a microchip, and they may not know to take it to someone who can, whereas they can certainly read a tag hanging from a collar.

Also, tags can include vaccination information.

The microchips do not.

On the other hand…

There are also advantages to microchips over tags.

A microchip is permanent in a way that tags are not.

Tags can get lost, or they can become too worn to be legible.

Then there is the problem with cats more so than with dogs that many owners prefer for their cat not to wear a collar.

Some cats can’t tolerate a collar.

Collars can get stuck in something, like a branch, and injure or even strangle a cat.

True, there are breakaway collars for cats that lessen this risk, but on the other hand they also thereby increase the risk that if your lost cat is found it will no longer have its collar (and tags) on.

But also, be sure to consider the pros and cons of all of your options before deciding.

Yes, there’s microchipping and there’s having your cat wear a collar with an identification tag (or camera), but there’s also the option of doing both.

In the end, you might decide that the best way to cover all your bases is to microchip your cat and to have it wear an identification tag.

Microchipping an Indoor Cat

Do you microchip a cat that is strictly indoors? Personally, I would say yes! 

If you have an indoor cat, you might be inclined not to bother taking precautions related to recovering it if it gets lost, because it’s not going to get lost.

Be careful there, though, because it’s really not that uncommon for even indoor cats to get lost.

A cat can bolt out the door when you’re not expecting it. If you inadvertently leave a window open, it can use that as a way to escape.

If you’re taking your cat to the vet or elsewhere in the car, it can slip away from you.

In cases of natural or manmade disasters – tornado, flood, hurricane, fire, etc. – it is unfortunate but true that pets and their owners are often separated. If the pet lacks proper identification, that separation may well be permanent.

So a good case can be made that even an indoor cat ought to be microchipped.

Bottom Line: Is Microchipping Worth it?

In my opinion, yes.

Precise numbers are hard to come by – you’ll see different estimates cited in different sources – but the evidence is strong that lost cats are much more likely to be reunited with their owners.

The most common figure given is that about 2% of lost cats without microchips are returned to their home.

But estimates are that ten times that many, twenty times that many, or even more lost cats with microchips end up back home.

There are pros and cons to microchipping, and I can’t say that it’s the right decision for every cat owner.

But a big pro that you’ll definitely want to take into consideration is that it works, that you’re a lot more likely to get your cat back if it gets lost, if you’ve had the foresight to have it microchipped.

Domestic cat sitting on sidewalk with people walking in background, New York, Teksas, Birleşik Devletler
Ever see a cat on the street and wonder who it’s human is? With microchipped pets, it’s a lot easier to find lost pets and return them to their homes.

Microchip Cat Flap

One final note, from the What’ll They Think of Next? Department.

You know those pet doors, where pets that are allowed out can go through a little opening with a flap?

There are now sophisticated versions of those pet doors that can read an implanted microchip.

It’s called the Microchip Cat Flap door.

You program the pet door by scanning your cat’s microchip information into it. That microchip then functions as your cat’s personal key.

When your cat approaches the door, it reads the chip and allows the cat to push through the flap and enter the house.

But if a cat without that chip approaches the door, the flap firmly blocks its entrance.

You can change the settings at any time to make it so that your cat also can’t get through the door, or so that it can come in, but once in it cannot go back out.

You can also scan additional microchips into it if you have multiple cats.

This is really interesting to hear about for me because we live in a neighborhood that is notoriously overwhelmed with stray cats.

As a matter of fact, our local vet performs FREE spay and neuter procedures if you bring in a stray – because the overpopulation of cats in our area is that much! 

And considering my above story about the lost fluff-ball that wandered into our home unannounced – I think this cat-flap product is really interesting! 

Let me know what you think about microchipping your pets in the comments below – do you microchip your pets?

Have you ever had a pet returned to you because your pet has a microchip?

I would love to know your thoughts on this! 


[1] WebMD Pets – Microchipping Your Dog or Cat

[2] Pet MD – Cat Microchips

[3] Great list of microchipping resources for further reading (if you want to get nerdy about it!)

CatHealth.com has an informative list of drawbacks for microchipping your cat. (great short read)


1. American Veterinary Medical Association: Us Pet Ownership & Demographics Sourcebook. Schaumberg, Il, American Veterinary Medical Association, 2007.

2. American Veterinary Medical Association: Micro­chipping Of Animals.  AVMA.

3. Stein Fj, Geller Sc, Carter Jc: Evaluation Of Micro­chip Migration In Horses, Donkeys, And Mules. Javma 223:1316-1319, 2003.

4. World Small Animal Veterinary Association: United States Microchip Report — 2006. Resource.

5. World Small Animal Veterinary Association: Micro­chip Implantation Sites Update — 1999. WSAV.

6. Mcconnico Rs, French Dd, Clark B, Et Al: Equine Rescue And Response Activities In Louisiana In The Aftermath Of Hurricanes Katrina And Rita. Javma 231:384-392, 2007.

7. World Small Animal Veterinary Association: Micro­chip Identification. Accessed February 2008. For More Information About The Various Implantation Sites In Differ­ent Species, Visit: Here.

3 thoughts on “Microchipping Cats: Common Questions, Complications And Side Effects (There’s A PINCH Involved)”

  1. Microchips are bad for small animals. So it is the size of a grain of rice? Multiply that by 20X and implant that between YOUR shoulder blades and tell me how good THAT is. A cat or small dog suffers discomfort. These are passive devices that get their power supply from the electromagnetic waves from the scanner to broadcast back to it. The device does not energize selectively and your animal is getting zinged by all kinds of stray EMF also. In fact, if they get by a hot spot, they can get zapped. Better do an EMF survey of your home and keep your pet away. Just how much EMF they receive probably determines just how much these devices raise the chances of your pet getting cancer.
    Since they have not standardized the scanners, your lost pet could have a microchip that gets missed. One way of getting around this is to look for it with a stud detector that also detects electrical wires. Yes, live electrical wires. It does not read it, but it serves as a universal detector and tells you something about what that chip is.
    These devices also malfunction and are very difficult to remove. If your pet is stolen, they may be cut badly to remove it.
    The application of these devices should be very limited and not normalized for general application. The multinational corporations promoting this are doing animal studies on our pets to build a case to force them on us. They are disengaged freaks and sociopaths. Say no to microchips for pets.

    1. Hi Lu,
      thank you for your response to this post – you have an opinion on this that I think many people share. This is one of the reasons I wanted to dive into this topic – there is a lot of information out there and a lot of different opinions. Of course, like with most things, there may be some risks involved with microchipping. Studies are continuously being done to explore the effects of things like microchips in your pet.
      From what I’ve understood with my research so far, there were some reports of tumors within animals (mostly mice and rats) who have microchips, yes. Due to other health factors and the varying size of the animal (which you’ve also mentioned), many of these studies couldn’t guarantee to microchip your cat would cause health concerns (similarly, they also couldn’t prove without a doubt that microchips don’t cause health concerns). Each individual pet owner (we hope) will gather as much information needed on this topic in order to make an informed choice on what they think is right for themselves and their pet.
      Thank you for sharing your thoughts – I am always looking for more information to add here and you’ve given some insight into what direction our team needs to do more research into!

      1. The pet I adopted was harmed by a microchip implant and I have looked into the technology and found the microchip industry to be one of fraud and deceit. They are essentially unregulated and promote their industry with propaganda to convince people to use their harmful products on their pets. I would speak out against them for those who cannot speak for themselves. Pet microchips cause them pain, illness, and exploitation. Microchips are bigger than a grain of rice, have an antenna that is not selective to EMF, and are made of things other than bioglass. Fewer than 10% of lost pets with microchips are ever returned to their owners by their chip. Adverse events occur at approximately 1 in 1,000 including chip failure, migration, abnormal mass, and tumor formation, infection, rejection, and death. Elevated death rates in shelters under mandate have been observed. After the pet is implanted with a chip, their inflammatory markers do not return to baseline and they carry it as a health burden.

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