Mistake Reading Cat Microchip

It is possible for a cat to end up being mistakenly re-homed even when microchipped. The microchip is the best identification method we have but it is not foolproof. An example proves the point, although in the story below the cat’s owner made some poor decisions which exacerbated the situation and enhanced the chance of losing her cat despite being microchipped.

Microchips are not infallible

Microchips are not infallible. Human error is probably the weak link.

A woman, Sam Cotton, unfortunately lost her home, at least temporary, due to a bad fire. She had to vacate and live in temporary accommodation. She wrongly decided to let her cat, Tiggy, live in the burnt out ruins of her home whilst she visited daily to feed her. Eventually her cat disappeared which does not surprise me, to be honest.

The home had changed out of all recognition which would have meant Tiggy felt she was in a strange place, no longer her usual home or territory. In addition, it was probably an uncomfortable place to be in as it was badly damaged by fire. I hate to be critical but why couldn’t she have found a better alternative such as a boarding cattery initially and them something more permanent? Mrs Cotton said that she was unable to settle in a temporary place and was therefore moving around a lot which encouraged her to leave her cat behind. I am sorry, harsh as it might seem, that would not have crossed my mind as an option and I am sure that applies to anyone who genuinely cares deeply about their cat’s welfare.

Tiggy was picked up and taken to a rescue center (Rolvenden Cat Rescue) who scanned her for a microchip and somehow managed to enter the wrong number (one digit was incorrect) in a database which failed to locate Tiggy’s owner (Sam Cotton) as a result of which she was re-homed with another person who now, some weeks later, has formed a bond and does not want to give her up. It seems, on the say-so of the shelter, that Sam Cotton took six weeks to contact the shelter which if true indicates a sloppy attitude to recovering her cat.

Anyway, the story highlights the fallibility of microchipping due to human error. Below are some ways this might happen:

Multiple Registries

In the USA there are many cat registries for microchipped cats. This may cause some confusion. It can lead to mistakes and perhaps a failure to identify a cat’s owner. A very useful search facility can be found on the Pet Microchip Look Up website as it lists almost all the registries. It is open to anyone to use and therefore you can check the registration at any time.

Scan Slowly

I don’t know if this is a genuine or common problem but scanning for the microchip should be conducted slowly and precisely to avoid missing the signal. Multiple scans should be conducted if a chip can’t be found.

Universal Scanners

Chips have evolved and have become more sophisticated. Because of their long life the older ones may not be detected by some scanners. It would seem that universal scanners are a “must have” in order to detect three different frequencies of transponder in the chip. However, universal scanners can still go wrong because e.g. the battery is run down, it needs maintenance or is not the most effective with respect to certain frequencies.

Problematic Scanning

Scanning for a microchip can be a problem, it appears. It is recommended that multiple scanning takes place over the pet’s neck, back and legs. Microchips can move so it is should not be assumed that the chip is in the same place where it was deposited by the vet or technician. Scanners have a circular area which should be placed over the location of the chip but the scanner may work better if the chip is outside the circular part of the scanner. This is problematic; caution and thoroughness might need to be exercised.


Metal can prevent the scanner detecting the signal from the chip. The metal can be in the cat’s collar or near the cat such as the cage, electrical devices and lighting etc..Does this mean scanning should carried out away from metal objects, even a consulting table?

Defective Microchips

Gail from Boston wrote a neat comment which I quote partially below:

…..We found that out last month when we chipped a number of cats – one cat 4 times – and the chips never registered on the scanner. When we discovered the entire batch was defective (we scanned chips not inserted yet), the vet had to surgically remove all of the defective chips (no easy feat) to be replaced with new ones.

Defective chips are another potential hurdle to accurate microchip identification.

Clearly microchipping is not infallible as a method to ID a cat despite being the most common and successful currently in use. Cat owners should be aware of this and consult with rescue centers accordingly when looking for their cat.

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Michael is retired! He retired at age 57 and at Aug 2018 is approaching 70. He worked in many jobs. The last job he did was as a solicitor practicing general law. He loves animals and is passionate about animal welfare. He also loves photography and nature. He hates animal abuse. He has owned and managed this site since 2007. There are around 13k pages so please use the custom search facility!


Mistake Reading Cat Microchip — 3 Comments

  1. I agree that the original owner was foolish, but people in extreme situations often don’t think straight. I’d imagine having your house burned down is quite a bit of a shock. When faced with such a stressful situation, people make stupid choices. It’s not the choice I’d have made, but I can see her difficulties. She needed to find a place to stay that takes cats quickly. We don’t know in what condition the old place was, maybe it still have walls, maybe a room or two were intact, she may have thought that it was preferable to a cage in a boarding place. Also, boarding is expensive, it might be OK for a week or two, but in her case it could’ve been longer. It takes time to arrange stuff with insurance, and then they’d pay for rebuilding. In the meantime, she needs to continue paying the expenses (e.g. mortgage) on her home in addition to the cost of the lodging. Most people would find it difficult to pay for two places at once. I’d personally just rented a hotel room that takes pets while looking for another place to rent or buy – but this isn’t an option for most people.

    I have to say that I were to get a cat from a shelter and find out within a few weeks that the cat belongs to someone else, I’d return the cat. Yes, it’ll be difficult, but I believe this is the right thing to do. In fact, in this case and in place of the new owner I might’ve agreed to keep it until the original owner finds a place to stay assuming she covers the expenses. Yes, we bond with our pets right away, I loved my kittens the moment I brought them home, but a few weeks bond is not the same as a few years bond, and doing a good thing for another person (who just lost her home) is rewarding in itself.

  2. This article is very important for people to understand. I agree that the original owner was very foolish to leave her cat behind in the burnt out ruins of the home. What was she thinking? The shelter is responsible for mis-inputting the chip number. I’m not familiar with UK laws; however, in the USA, the original owner very well could take the case to court and may very well win due to the shelter’s negligence. That being said, the case could very well be decided the other way due to the negligence of the original owner just leaving the cat in the burnt ruins. It could be decided by the court that in the best interest of the cat, the new home is better suited.

    We have a universal scanner in our shelter as well as the original one that resembles a TV remote. Even with the universal scanner, some of the very old chips still don’t register. We constantly check the batteries to ensure a strong signal.

    The other problem not brought up in this article is that sometimes a batch of bad chips gets shipped out. We found that out last month when we chipped a number of cats – one cat 4 times – and the chips never registered on the scanner. When we discovered the entire batch was defective (we scanned chips not inserted yet), the vet had to surgically remove all of the defective chips (no easy feat) to be replaced with new ones.

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