Pet Factsheets

Permanent identification of your cat

Stray dogs and cats are a big problem in many countries. In the UK alone it is estimated that more than £250 million a year is spent by local authorities, police forces and animal welfare charities rounding up and looking after stray cats and dogs. It is much harder to calculate the emotional cost to both the owner and animal when a pet is lost. Many pet cats in the UK have access to a cat flap or similar, meaning it is easy for them to stray away from the home or be stolen.

Collars with tags are useful but are easily mislaid by cats. Microchips are a more permanent solution, and are a quick and efficient way to reunite owners with their lost pets, even across international frontiers. Ear tattoos are another form of permanent identification, but these are now no longer widely used due to the easier alternative of microchips.

Why is it important to be able to identify a dog or cat?

Microchipping for cats is not currently compulsory, unless you plan to travel with your cat under the PETS scheme. However, it is a very good idea to have your cat microchipped for various reasons. 

Stray dogs and cats can wander over large distances and unless the animal carries some permanent identification it is unlikely that anyone finding it will be able to contact the owners or know how to re-unite them. Animal shelters only have limited room and unless the owners come forward it is likely that the animal will be given a new home, or even eventually be put to sleep. The information stored on a microchip implant is held on a central database allowing owners to be quickly contacted. This saves time and distress for the owners and their pets, cuts down the numbers of strays in shelters and saves money for the organisations which look after them.

Permanent identification of dogs and cats is essential for implementation of the Pet Travel scheme (PETS). DEFRA requires that a pet transported between the British Isles and designated countries needs to be permanently identified so that checks can be made to see that the animal has received the necessary anti-rabies vaccinations. The most common method of identification is a microchip, although tattoos of identification numbers are also permitted, providing the animal was tattooed on or before 3rd July 2011, and it is clearly legible. 

The presence of a registered microchip may help to determine who owns a particular animal should an ownership dispute arise. As cats are often free-roaming, and it is not uncommon for a pet cat to live/feed in more than one house, microchipping can be essential if arguments over the correct owner occur.

What is a microchip?

A microchip is a small tube about the size of a grain of rice that contains a unique 15 digit code (identification number); this number is registered on a national microchip database and should also be noted down on your pet's vaccination record and/or passport or Animal Health Certificate.. The chip is made of an inert material which means it has no power source and won't be rejected by your pet's body. To retrieve your pet's identification number, a scanner is passed over its body. The scanner sends out a magnetic field, which picks up the 15-digit code imprinted on the chip which shows up automatically on the scanner's screen. The person scanning the pet can then contact the microchip database and provide this code. The database providers can then notify the owner about the discovery of their animal via the owner's registered contact details. Vets, police, rescue centres and dog wardens will all have microchip scanners.

How is a microchip inserted?

Microchips are injected under the skin at the base (scruff) of the neck with a wide-bore, sterile needle. Once the chip has been implanted by your vet, or another qualified person, it is supposed to remain in place due to its special cap that prevents movement, however it is not uncommon for them to move around a little under the skin, and so when an animal is scanned it is usual practice to scan the whole body, not just the scruff. 

Is the microchipping system foolproof?

As the code is permanently embedded on the chip there is no risk of the code being tampered with or changed. Equally importantly, the 15-digit code gives more than enough capacity for every pet animal in the world to be given their own unique number. In the unlikely event that the microchip may fail, and the identification number will be unreadable by a scanner, your vet may need to insert a new one; the registration for both of these chips should then be maintained in case the original chip is picked up on a future scan.

There is some international agreement on microchip standards so that microchips implanted in one country should be readable in others. Where possible ISO (International Standards Organisation) Standard microchips meeting specification 11784 or Annex A to 11785 should be used and vets in Europe will have readers for these chips. If you are planning to take your pet abroad you should make enquiries about the type of microchip being implanted in your pet. For example, some of the microchip companies in the United States do not use ISO standard chips and compatibility between chips and readers may be an issue if your pet has been microchipped in this country. If the microchip does not conform to ISO standards, it may not be able to be read by a standard UK microchip reader when the animal is checked at the time of travel to the UK or when in a European country. If your pet does not have an ISO microchip you should carry an appropriate microchip reader when travelling with your pet.

Are there any alternatives to microchips?

Dogs and cats can be fitted with a collar and address tag, but collars can easily become lost and the tags damaged. Cats may also get their collars caught when climbing trees or squeezing through tight gaps and there is a risk of strangulation, so a quick release feature is essential. For many years tattoos have also been used to permanently identify an animal, but this method has a number of disadvantages - the ink can fade and become unreadable, the animal has to be given a general anaesthetic to keep it still when applying the tattoo, and tattoos can also be altered by further tattooing. There is also a risk of errors when writing down any long number and it may be difficult to print a long code on the skin of smaller animals. Cats travelling abroad may use tattoo identification instead of a microchip as long as the pet was tattooed before 3rd July 2011, the tattoo is legible and the pet was vaccinated against rabies after the tattoo was placed. This information must be noted in the pet's passport or Animal Health Certificate by a veterinarian as appropriate.

Are there any risks involved in microchipping?

Microchips should only be implanted by a veterinary surgeon or suitable trained person as injuries due to poor implantation technique have been reported. Microchips can be inserted at any age. The microchip can be inserted without a general anaesthetic. A local painkiller is likely unnecessary but speak to your veterinary surgeon if you have concerns. Any pain is minor and short lived and the chip will stay under the skin surface for the rest of your pet's life. Occasionally the insertion site may ooze a few drops of blood after insertion. The chip is sterile and although there is a very slight risk of introducing infection this could easily be treated. The chip can move under the skin away from the original site but as long as the chip stays intact it can be read anywhere in your pet's body. There have been documented cases of tumours associated with microchips, but the risk is considered very low compared to the millions of animals worldwide that have received microchips with no associated problems.

How does a finder know that a lost animal belongs to me?

Once the microchip has been implanted and the owner details registered, the animal is permanently listed on a microchip database. Many microchip providers pre-register their microchips to one database provider which means that if an owner does not register their details, the company selling the chips might be able to trace the location of where the chip was implanted. These database companies will maintain contact details and registration information for other microchip database providers so registration with multiple companies is unnecessary.  The largest UK database is Petlog, which has 13.4 million pets currently registered. Authorised people can contact their ‘found’ line 24 hours/day, 365 days/year and they are also linked to European networks so can help reunite pets that have even left the country. 

When an animal is found its microchip is read with the scanner and the number checked on the database. This provides information on the owner who can then be contacted and informed of the whereabouts of their pet. Keeping information up to date with the database in the event of moving home or changing phone number is very important as the microchip will be ineffective without the correct owner contact details. A very common problem with stray cats handed in is that they are microchipped, but the contact details are out of date and so although it is known that the cat is owned and loved, it is difficult to re-unite them with their owners. 

Do microchips have any additional uses?

For cats that go outdoors, the use of a "cat flap" to allow free access for the cat to go in and out of the house may be helpful for some owners. Pet doors are available that have sensors in them that can be programmed to recognise one or more individual pet's microchips in order to allow only these pets access to the house while preventing other animals from entering. Feeding stations with microchip readers are now available - the feeder has a cover that can be programmed to open only for the pet with the registered microchip. This can be useful for multi-pet households in order to prevent overfeeding, or to make it easier when one pet in the household needs a prescription diet or medication in its food to which other pets should not have access. In the future, it is also hoped that microchips might be able to improve the monitoring of disease, for example microchips that will monitor blood sugar levels for diabetics in order to reduce the necessity of frequent blood sampling and costly vet visits.