Microchipping – What’s the point!

BenVetPhotoby Ben Sturgeon, BSc;BVM&S; Cert EP;MRCVS

It will come as little surprise that I have chipped quite a few foals recently.  After a few months out in fields they are now being brought in and the identification process is in full swing.  Many people are very happy with the requirements but I have a few clients who simply ask “is it safe?” Or “What’s the point of this?”  The answer can be quite long winded.

Firstly the answer according to the “party line”.

Following the introduction of compulsory passports for all horses in 2005, new European Union regulations, which came into effect on 1st July 2009, meant that all foals born must be microchipped before an owner can apply for an equine passport.

The new rules do not apply to older horses with an existing passport which were born before 1st July 2009, but any foal (horses, ponies, donkeys or mules) born after this date must be microchipped within six months of birth, or by December  31st of the year of birth, whichever is later.  Horses born before 1st July 2009 which do not have an existing passport, must also be microchipped when the passport is issued.  Failure to correctly identify animals under the new rules could lead to a fine.  Even if your horse is not affected by these regulations, microchipping is increasingly being seen as the best way of identifying an individual horse and it has advantages over the other methods of identification.

There are three main methods then to identify your horse or pony:


  • Provides a supposed guarantee of identity. Microchip implantation is not completely pain free (utilizing a relatively large needle), but does appear to inflict less pain and suffering than other identification methods such as hot branding or freeze marking.

Freeze marking

  • Involves a cold branding iron being held on the skin for 7-10 seconds in dark horses to make a white mark, or 12-15 in lighter horses to destroy the hair growth follicles and make a bald mark. Freeze marking may deter the theft of horses and ponies, which can lead to neglect, poor welfare and slaughter, but the process itself can cause significant suffering.

Hot branding

  • Involves the application of a very hot iron to the skin for several seconds or until the hide turns a light tan colour. This causes significant pain and suffering – significantly more than freeze marking or microchipping. The RSPCA believe that this pain and suffering is unnecessary because there are the effective alternative means of identification available which cause less suffering.


A microchip is a small implant, about the size of a grain of rice covered with an anti-migration sheath, which contains a unique serial code. It is inserted, via injection, into the nuchal ligament on the left side of the horse’s neck. This procedure must only be carried out by a veterinary surgeon.  The horse owner’s details and a unique serial code are stored on a computerised database, which links the owner to the horse. It is therefore important that the owner’s details on the database are kept up to date.  Once the microchip has been implanted, it can be read easily by an electronic microchip reader.  The microchip cannot move or be seen – therefore, it is tamper-proof and permanent, unlike other more traditional methods of identification, such as branding.  Although microchipping is considered to be very safe, there is a very small risk of bruising and abscess formation at the site of implantation, and on very rare occasions, possible migration of the microchip.


The introduction of horse passports and microchipping has been widely welcomed. The EU legislation ensures that horses, which have been treated with veterinary medicines not authorised for use in food producing animals, cannot be slaughtered for human consumption in Europe.  This has obviously become more important following the recent findings of horse meat in our national diet.  If horse owners in the UK do not comply, there is a significant risk that we would lose up to 70% of horse medicines, including common medications such as ‘bute’, which would have grave consequences for equine welfare. It is intended then that microchipping will make the horse identification and passport system more robust.  This reliable, sophisticated and cost-effective technology will also help to reunite owners with their horses in the event of theft or escape, aid disease surveillance and help animal welfare organisations with prosecutions in cases of neglect.

All well and good?  So what’s the problem or why the concerns?

…So secondly the “scaremongers”.

According to the United States Food and Drug Administration (FDA); The potential risks to health associated with the device [microchip implant] are: adverse tissue reaction, migration of implanted transponder; compromised information security; failure of implanted transponder; failure of inserter; failure of electronic scanner; electromagnetic interference; electrical hazards; magnetic resonance imaging incompatibility; and needle stick injury.

And there are also reports of nerve damage and tumour development and even computer viruses!

The first rule of any medicine is prima non cere, or do no harm.  So are any of these concerns real or is there a sensible alternative argument?

Abscesses, lumps and infections have occurred in horses because of microchip implants but have also occurred with and can occur with any vaccine or injection and currently there is no evidence to suggest that they are more likely to cause a higher percentage of infections.  In my experience I have had one horse developing a post implantation reaction, but several (approximately 4) from vaccination reactions.

Nerve damage was reported by one vet (from Holland) in 2005 subsequent to microchipping but is also reported with other injections.  The incidence given the multiplicity of microchip insertions appears to be negligible.

Adverse tissue reactions, muscle changes and even cancer are perhaps the most concerning.  It is unsurprising that muscular changes do occur at the site of implant.  In one study of 16 horses that had been submitted for post mortem examinations (for reasons other than chipping) the chips had caused absolutely no ill effects (microchips were covered by a thin capsule of fibrous tissue, sometimes with a minimal amount of inflammation), in two animals that were affected, they had been chipped recently and there had not been time for the injection site to heal.

Of more concern is the reporting of Fibrosarcoma (a skin tumour) in a cat, and in Rodents under experimental conditions, and have been suggested to be associated with the anti-migrational sheath.  No cases have been reported in horses at all and we should be wary of extrapolating results from other species.  However, despite again the extremely low incidence, and given the number of animals microchipped, we should not ignore any changes at the microchipping site.

Movement or migration of the chip has always been of concern to owners and migration has been documented again in small animals.  This appears not to be the case in horses primarily because of the fact that we place the chip into a ligament rather than under the skin as with small animals.  Research has again found that “migration” within horses is not due to microchip movement but because of muscle development around the chip.  Given that most horses are chipped as a foal and that growth is obviously ongoing it is perhaps unsurprising that the chip becomes “deeper” within tissues as the animal ages.

Reliability of the chip is perhaps the last area of concern.  Companies that provide the chips claim that they will last the lifespan of the animal and as yet absolute failure of the chips is again in negligible numbers.  Many cases however, are recorded where the chip is simply not found, but this is largely due to the scanner being of insufficient quality to detect them.  Basic scanners usually have a capacity to detect chips at a distance of up to 7 centimeters. Considering that chips are usually embedded at approximately 2 to 3 centimeters below the skin surface, basic scanners are frequently sufficient.  However, as muscle growth can cause the chip to end up deeper below the skin surface, this can cause readability issues.  In a recent study using 428 microchipped horses, a basic scanner only detected 90% of the microchips.  However, with a more advanced model capable of scanning at a distance of 12 centimeters, all 428 microchips were detected.  It has also been suggested that some duplication of microchip numbers has occurred and with microchip kits being sold via the Internet it may be difficult to know if a microchip identification number is unique.  I have yet to find any record of this occurring but greater control or standardization of chip numbers is perhaps needed on this point.  Finally, on this point and with trepidation it has been demonstrated that a computer virus can be transmitted to microchips affecting their status.  Whilst I know not of a reason for this, I generally don’t understand some people and can only hope that appropriate “safety” is employed by the various databases.

So what do we make of all this?  Aside from fulfilling the legal requirements we as vets must be happy that what we are doing is to the benefit of the individual animal and to the general population (people included).  In my opinion the microchip is safer, less injurious and painful, and less manipulative than other methods of identification and affords the owner with peace of mind, the vet of clinical safety and the general public of medical standards being upheld.  But we should always ask.

Author: Features Editor

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