Pet Microchip Information

Health Effects
Lost Pets
Background (Risk Assessments)
Broken Information Chain
The Problem with Microchip Mandates
Compounded Veterinary Procedures
Cats Versus Dogs
Failures of the Microchip Tracking System
Alternative ID Methods
Recommendations for a Pet Friendly Community


Pet microchips can cause pain and illness through acute and chronic inflammation, toxins in encapsulants and electromagnetic effects.  These are significant effects and should not be marginalized.

When a microchip is implanted in a cat or dog they suffer pain through acute inflammation for at least three days.  The inflammatory response continues for approximately a month until the implant is covered with scar tissue so animals need care and considerations for some time after implant.  Implant techniques into the pets tissues and plastic coatings are intentionally designed to be inflammatory, to cause the inflammatory response that covers the microchip with scar tissue.  The American Veterinary Medical Association (AVMA) sites an independent study on beagles where only 87 of 90 implants formed the scar tissue.  So what happens with the inflammatory response when no scar tissue forms?  Does it never start or never stop?

The plastics used as sleeves or to coat or encapsulate microchips can contain toxins that migrate to the surface over time, releasing into the pet.   Parylene C is essentially chlorinated poly-dimethybenzene and so benzene would be incorporated into the polymer chain.  One should consider the ways that benzene causes cancer when considering the safety of the polymer as well as any impurities in parylene C.  Promoters will tell you it is safe, that it is inert.  Being inert is also one of the outstanding characteristics of Benzene.

Plastics are also used in place of glass.  Patents held by one manufacturer of such a microchip describe plastic encapsulants as silicone with a polyester sheath.  There are no enforceable regulations or restrictions on what materials can be implanted in a pet as a microchip coating or encapsulant.

Cancer studies on these materials may not actually be useful because the impurities in them depend a lot on how they are manufactured.  The pet microchip industry has virtually no regulation.  Specifications and quality controls are left to the manufacturers discretion.

These plastic coatings are said to be put on pet microchips to prevent migration, a major failure of the microchip system.  There are no third party studies that show any of them actually do that.   The use of such coatings leads to questions about experimentation.

Glass is a non-crystalline amorphous solid.  It can contain impurities also. Although the diffusion of them to the surface is very slow, there are still issues.  Lead is commonly added to glass to make it easier to process.  What are the protections from the use of lead in the glass of pet microchips?  Just what is bio-compatible glass?  One manufacturer gives heavy metal specifications for their pet microchip transponder glass as, “The heavy metal content for the elements lead, cadmium, mercury and hexavalent chromium is below 100 ppm.”   That would be 0.01%.  Does the pet guardian know to ask for specifications on the glass used for their pet’s microchip?  And just what should they be?

Pet microchips can be made with ferrous materials that give them magnetic potential.  Human microchip tests for magnetic potential are described in the FDA Guidelines.  Pet guardians are not advised of the dangers, here.  Are they warned not to use magnetic pain therapy for their pets?  The AVMA reports that surrounding tissue is not damaged during MRI, but conflicting reports exist elsewhere and MRI manufacturers give warnings.  There are questions about MRI safety due to movement, also.  Pets should have more rigorous standards for magnetic potential than humans.  But they have none.  There are no regulations on magnetic potential for pet microchips.  The magnetic potential of three different microchips are shown in the following:

Claims that pet microchips are passive, activating only when scanned may be in part true about the actual microchip but the implant also has an antenna.  The antenna is not a selective receiver and can intercept, generate current with, and re-radiate other electromagnetic waves in the environment.  If the wave received by the antenna is tuned out before the microchip, it is simply re-radiated.  Electromagnetic waves in our environment are of health concerns as they can cause oxidative stress to our cells .  Implanting a microchip, that has an antenna, in a pet would need to be considered as to having an adverse effect on their health.

There are standards for pet microchip implant sites, radio frequencies and scanners, but none that protect pets from toxins in encapsulants or set limits for magnetic potentials and electromagnetic effects.

Medical microchips implanted in a sick person to manage or cure illness can benefit their health.  Implanting microchips in an otherwise healthy animal only creates illness.


We are told that the benefit of the pet microchip system is to return the pet to it’s guardian and protect them from being euthanized in shelters or otherwise lost to us.  It is also used to hold people accountable for pets that do harm.  How many pets actually benefit from this?  With all the data collected, we are presented with virtually no hard facts.

A 2012 survey of approximately 1,015 pet guardians reported by the ASPCA gives an idea of how many pets benefit from having ID.   It reports that 14% of dogs and 15% of cats may get lost in a 5 year period.  That would extrapolate to 39% over an average 14 year lifetime of a pet.  Approximately 85% of the lost pets are recovered by various methods.  Even without recovery by ID, the recovery of lost pets is 76%.  That suggests that no more than 9% of pets could benefit from having ID during an average lifetime.  Dogs were mostly found by neighborhood search and returns and cats mostly found their own way home.

The ASPCA Survey recovery rate of lost pets without ID of 76% is a whole lot different than the 10% implied by HomeAgain claims that 90% of lost animals would not be recovered without ID.  The company has been in the pet microchip business for decades and boasts of 2 million reunions, not specifying the time range or geography.  Nor do they tell you how many pets have been in their database.

The study includes household with multiple pets and pets that get lost multiple times.  The data is based on the number of pets.  Data from the study on lost and recovered pets is summarized as follows :

Survey of 5 Year Period Dogs Cats Total
Total Survey 815 503 1318
Lost 110 74 184
Not Recovered 9 19 28
RECOVERIES, Total 101 55 156
Neighborhood (Search & Return) 56 16 72
Shelter 6 1 7
ID 15 1 16
Self 20 32 52
Other 4 5 9
Lost, % of Total Survey 13.5% 14.7% 14.0%
Recovered, % of Survey 12.4% 10.9% 11.8%

The information in the ASPCA study suggests that 3% of pets would be recovered by ID over an average 14 year lifetime of a pet and 6% of pets would remained lost.  Would those 6% benefit from having ID?

The  data from the study shows that 36  of the 184  lost pets had microchips, but does not show how many recovered pets had them.   With some small discrepancy in the survey data, it appears that all 16 pets recovered by ID had microchips and that the other 20 pets with microchips were among the 28 pets that were unrecovered.  The data shows 72% of the lost pets had ID and 20% had microchips.  If all pets recovered by ID were recovered by their microchip ID, it would indicate a microchip recovery rate of 44% for the lost pets in the study.  However, only 8 of the unrecovered pets did not have ID, so the potential gain for having all pets with ID is only 1.7% over an average 14 year life of a pet.  If microchip recovery rates are applied, that is less than 1%.

So with 3% recovered by ID and 6% remaining missing what is happening?  What happened to those 20 pets with microchip implants and 8 that did not?   Maybe someone found them and just decided to keep them.  There are many possibilities.

But it is a sad fact that the reason many animals are not recovered is death on the roadways.  It is reported that 1.2 million dogs and 5.4 million cats are killed each year in the US.  Considering a pet population of 183 million, that could be estimated as 300 million including stray and feral cats and dogs, that comes to 2% per year and a chilling 31% over the average life of a pet. This more than explains the pets not recovered in the ASPCA survey and exceeds the US annual euthanasia rates of 0.67 million dogs and 0.86 million cats.  Pets lost to death on the roadway is something pet microchip promoters do not figure in the potential benefit of pet microchips.  The ASPCA study suggests that the pet loss in the roadway could be as high as 5% over the lifetime of a pet.  The majority of cats and dogs lost in the roadway would be stray and feral to make up to the 31%.

So in summary, 39% get lost, 30% get recovered without ID, 3% get recovered by ID, and additional 1% could be recovered if they had ID and 5% are not recovered, possibly lost in the roadway.

Pet guardians should not be given the a false sense of security to allow their pets to roam.  No form of ID will protect them on the roadway.

Many forms of ID are available. So why should a guardian opt for implanting an electronic device in their pet instead of using a collar or maintaining a current picture for facial recognition?


Medical microchips are an emerging industry.  The microchip was invented in 1959.  Some of the first human implants were demonstrated in 1998.  The FDA classified their use as Class II Medical Devices in October 2004 and they have been implanted in humans as such since 2006.  However, the FDA official involved in their classification was later became a highly paid employee of the first company approved for the classification.  The industry has been plagued by questions of integrity and a lack of due diligence for regulation and cancer review.  False advertising is pervasive as FDA health risk labeling recommendations for humans are not required for pets.

Animal testing has been conducted since at least the 1980’s.  Adverse event reporting has been inconsistent, with no mandatory reporting throughout the world until recently.  Some earlier data is available through the British Small Animal Veterinary Association (BSAVA).  The AVMA summarizes the BSAVA voluntary adverse reaction reports on their website.  It shows 391 adverse events reported for a period of 1996 through 2009 relating to 3.7 million registered pets with microchip implants.   Of the 391 adverse events, 301 were migration (includes lost), 36 failed and 54 were reactions.  That would indicate an event rate of 1 out of 9,462 implants, commonly sited as 1 in 10,000 and generally dismissed as insignificant.  The AVMA does not make their own risk assessment, but references the World Small Animal Veterinary Association (WSAVA).

It is a committee of the WSAVA  that has established the position on pet microchip implants based on the early BSAVA voluntary data, that the other organizations reference as a recommendation.  The WSAVA committee concludes on health risks:

While it is not possible to claim that the reaction to an implanted transponder in a companion animal will NEVER induce tumour formation, the Committee is unanimously of the opinion that the benefits available to implanted animals far outweigh any possible risk to the health of the animal concerned.

The position statement also takes exception on the registries:

The benefits of transponder implantation, backed up with a reliable, accurate and available database, far outweigh this risk.

The WSAVA is a global organization that includes member nations that are major microchip producers.  There are varying views throughout the world on cats and dog as companion animals or livestock.  The WSAVA accepts the Five Freedoms as standards of care but still condones the consumption of dog and cat meat .  Cat and dog guardians in America generally regard them as family members.

Adverse Event reporting in the UK became mandatory with the mandatory microchip implant of Dogs. The UK’s Veterinary Medicines Directorate (VMD) assumed the task of adverse event reporting there in April 2014.  Mandatory microchip implant of dogs and mandatory adverse event reporting went into effect in England in February of 2015 and in Scotland and Wales in April of 2016.

The first summary report was issued for the period of April 2014 through December 2015 and dismisses the adverse events as “very low”.  The 2014 voluntary data shows 28 reports in 8 months (10.25 reports/month) for a population that would have had between 60% and 86% of dogs implanted.  This is compared to the mandatory implant and reporting  of the 2017 data with 1,044 reports (87 reports/month) with 95% of the dogs implanted.  That would indicate a factor of approximately 7 for voluntary versus mandatory reporting.

The recent UK adverse events associated with microchip implant appear to be significantly higher than the original voluntary data that was the basis for the WSAVA position on pet microchips.  The data through the end of 2017 is shown below. The estimate for the total cat and dog population of the UK is 16 million with 8.5 million dogs subject to mandatory microchip implant.   Mandatory microchip implant for dogs throughout the UK took effect in April 2016.  The total number of implants is not tracked, but estimates at various points in time are given.  To do a good comparison to the earlier data for risk assessment, information should be collected over a similar time period, however, the data to date gives us fair estimates that indicate it is approximately ten times higher than the earlier data that has been used for many risk/benefit analysis.


Period Total AE Dog AE Migration Failure Reactions
4/2014-12/2015 1,420 1,195 729 630 61
2016 2,063 1,861 876 1,090 97
2017 1,044 843 407 584 53
Total 4,527 3,899 2,012 2,304 211

The overall data suggests an adverse event rate of approximately 1 in 3,000.  The Reactions include rejection, infection, tumors and death.

But if we look closer in the data, we find it is even higher, when adjusted for the under reporting prior to mandatory reporting. The UK Government claims that 86% of all dogs had microchips as of April 2016.  A year later, the claim is that 95% of all dogs have microchips.  Based on this, the adverse event rate is approximately 1 in 1,000, calculated as follows:

From the 2016 and 2017 adverse event data sets we extracted the following for Events First Detected the year starting April 2016:

ADVERSE EVENTS Total AE Migration Failure Reactions
All Animals               1,678            661           938             79
Dog Only               1,406            739           615             52
Dog Implants Per Event             1,048        1,994       2,396      28,333

Based on the population estimates:

Population Implanted 4/1/16 – 3/31/17
Population (9% of 8.5 million)           765,000
Births (1/12 of 8.5 million)           708,333
Total Dogs Implanted       1,473,333

The UK Government also reports that 61% (or 69%, depending on interpretation) of dogs had microchip implants as of 2012.  Another UK Government post in February 2013 claims 60% of dogs had microchip implants at that time.   This would indicate that the population base that was implanted with mandatory reporting in effect would be around one third of the 8.5 million.  So the overall rate of 1 in 3,000 at one third the population would support the 1 in 1, 000 rate.

Another way to estimate the adverse event rate would be to consider the 2017 data as reflecting the birth rate.  That would indicate the rate is 1 in 840.

The BSAVA, the UK VMD,  the AVMA and the WSAVA are not reporting on these statistics.

This mandatory reporting of Adverse Events is yet also understated as shelters do not report on pets who develop communicable diseases after being implanted with a microchip upon intake to the shelter.  Should they develop communicable diseases or even die from them after implant, it is treated as just another death in the shelter.

The Dogs Trust, a major UK humane organization, lobbied for the mandatory microchip implant of all dogs there.  Their 2017 annual report announces the successful reduction in stray dog and attributes it to the mandate, despite their direct involvement in spay/neuter programs that were more likely to be the actual cause of the reductions in strays.  Dogs Trust also ignored the increase in their shelter deaths that occurred when the mandate was implemented.  The 2017 shelter death rate is the highest of their last 10 years.  The only other time it approached the 2017 level was after they first initiated their microchip programs.  The shelter deaths from 2014-2015 as compared to 2016-2017 show an increase of 90 dog deaths per year in the Dogs Trust shelters.  Yet there appears to be no such adverse event reports made as required by the dog microchip mandate laws.  We have sent a report to the UK authorities and asked them to investigate.


Adverse effects relating to cancer that have been validated are tumors that actually grow on the microchips.  Reporting tumors or other adverse events associated with pet microchips to the Veterinary FDA is not mandatory.  Four veterinarians were involved in treating this dog for cancer and never reported the tumor as an adverse microchip implant event.  Most pet guardians do not know that they can make the reports.

The incidence of tumors growing on the chips is rare.  But despite the existence of these tumors, there are no known accepted, published studies on how the cancer rates of cats and dogs with microchips compare with those who do not have them.  Although it appears that pet cancer may be on the rise, pet microchips are not being scrutinized.  Pet cancer is actually not a reportable illness and there is apparently no third party surveillance for it.  Pet data remains obscured by a lack of standardized reporting, yet a lack of proof of harm is used by promoters to validate the safety of microchips for pets and people.

What we do know is the pet cancer treatment industry is growing by leaps and bounds.  Their projections are partly based on the, ” rising prevalence of pet cancer.”.

Manufactures distributing pet microchip products in the United States include Datamars, Trovan, AVID, Altifex and Destron Fearing/Digital Angel.  These products are mainly distributed through non-profit pet identification registries with volunteers who are not trained or knowledgeable about the technology or adverse effects.  AVID won a lawsuit against Datamars in 2004 for technology infringement and making false advertising claims that harmed consumers, yet they dominate the market of today with the same practices.

With the pet microchip industry essentially unregulated, microchip mandates for animals can be used to provided a corridor for the industry to use our pets as test subjects for risky products without consent or compensation.  New products can be introduced into the microchip market without notice.  These products are frequently made available at low cost so that the product can be field tested.  Destron-Fearing set the precedent for polymer coating part of the microchip with a polypropylene cap over 20 years ago.  The polymer is supposed to be medical grade polypropylene that could be a simple hydrocarbon polymer that would have minimal impurities and additives.  But now there are microchips on the market that are coated with Parylene C, a plastic coating that is basically chlorinated poly-dimethylbenzene.  It appears to have been introduced without cancer testing.  Such a microchip is being promoted by a UK microchip producer called Pet-ID Microchips who supplied microchips for the UK dog mandates.

Merck Animal Health, who has distributed the Destron-Fearing polypropylene cap for years under the brand of HomeAgain, now offers the smaller Parylene C coated microchip to consumers.

Datamars currently sells “the only bio-polymer microchip in the market” that is being used on our pets.  They claim it is FDA approved, but do not say what for. The FDA Center for Veterinary Medicine has no knowledge of the product.  It is sold on the internet, represented as a glass microchipDatamars, a Swiss livestock management company, appears to dominate the UK market, based on the adverse event reporting.  Their 2007 pet microchip patent includes a plastic microchip that is described as a silicon filled pet microchip with a polyester sheath, but other plastics are also referenced.  It was registered with ICAR in May 2012 and the North American division started promoting it for sale around 2014.  The Veterinary FDA has reported it has done no review.  It is currently being sold on the internet without disclosing to consumers that it is not glass encapsulated.  So far as we can tell, the only thing in the packaging that distinguishes the plastic pet microchip from their glass product is the orange cap used on the syringe. That is not what is shown in the pictures on one sellers website.  There is vague reference made to the fact that it is other than a standard glass microchip, but no say of how besides it’s smaller size.  The consumer would otherwise have to discharge the microchip for inspection or measure the diameter of the syringe tip and research the microchip to know it is not a glass encapsulated microchip.

Third party studies, including the polypropylene cap microchip, indicate that the cap does not prevent or reduce migration.  The 2016 and 2017 UK Adverse Events that show the Destron-Fearing polypropylene microchip (transponder numbers starting 985) accounts for approximately 8.8% of the migration events (some by this number may be parylene C).  While it cannot be determined from this if the cap reduces migration or not, it can be said that they do not prevent it.

The Parylene C coated Pet-ID Microchip (transponder number starting 958) accounts for approximately 7.5% of the migration events.


The FDA guidance document that is part of the human microchip classification determination lists the potential risks to health associated with microchips.  Cancer risk was not considered in the FDA review.  The recommended labeling for human microchips to mitigate the health risk are warnings about:

  • Adverse Tissue Reaction
  • Failure of implanted transponder
  • Failure of electronic scanner
  • Electromagnetic Interference
  • Electrical Hazards
  • Magnetic Resonance Imaging Incompatibility
  • Needle stick

The FDA considers pet microchips to be veterinary medical devices and they are regulated by the FDA Center for Veterinary Medicine.  The programs for adverse event reporting and advertising/labeling guidance are voluntary and regulations pertain mostly to record keeping requirements.

Manufacturers distribute their products through non-profit registries to veterinarians and pet owners directly.  They are required to label with manufacturer and/or distributors information, but generally contain no health effects warnings as this is not actually required.

So when is the pet owner informed?  How is the public informed?  Do our public information programs include these FDA warnings and health risks?  Would pet microchips become an adoptability issue if they were recognized as a health liability?


Microchip mandates do not solve euthanasia problems from pet overpopulation and detract from resources that could be used towards spay/neuter programs that do.  There is considerable misinformation promoted throughout pet shelter programs by special interests that tie microchip implant programs to spay/neuter programs and subsequently take credit for reductions in euthanasia from spay/neuter programs, creating misconceptions that microchip programs reduce euthanasia.  These are harmful misconceptions that lead to improper utilization of resources and more pet deaths.

The Dogs Trust, a major UK humane organization that promoted the mandatory microchip implant of all dogs there, has declared the program a success and is expanding internationally.  However, they ignored the increase in their shelter deaths that occurred when the mandate was implemented and they had direct involvement in spay/neuter programs that were more likely to be the actual cause of the reductions in strays.

The ASPCA itself posts some fuel for such misinformation.  The ASPCA says statistics show euthanasia rates are dropping.  They show a reduction of 1.1 million per year since 2011.  The post on their website attributes the drop partially to improved returns to owner and improved adoptions.  But there is really only 0.4 million of the reduction that should be attributed to such.  The data on their page also shows that 0.7 million on the 1.1 million reduction is in reduced intake.  Reduced intake is generally attributed to spay/neuter programs, but that is not mentioned anywhere on the page.   How is it they do not mention the most important spay/neuter programs in their statistics on euthanasia?  Microchip proponents would attribute the reduced intake to returns to owner made outside the shelter system and would claim it as the success of the microchip system.  They would claim the 0.7 million reduction in intake as increased returns to owner.  The flaw in the claim of attributing reduced intake to improved returns to owner in this case is that improved returns reduce adoptions and they are claiming both are occurring.  If returns to owner and pet adoptions are both improved, there would be an increase in pet ownership that would actually be the cause of the reduced euthanasia. Certainly the pet population growth is many times the euthanasia reduction.

Euthanasia of adoptable pets occurs when the pet population grows too fast.  The only way to change that without increased deaths is to reduce the births through spay/neuter.   There is no getting around that.  When the population is controlled and euthanasia is not a threat, returning a pet to the owner it left does not save it’s life.  It may even find a better one.

A 2012 survey of approximately 1,015 pet guardians reported by the ASPCA give an idea of how many pets benefit from having ID.  The study shows that approximately 3% to 4% may benefit from ID for recovery over their lifetime. The benefit of ID could be provided by any form of ID.  How can it be that an entire population should be mandated to have that one form of invasive ID?  While there are some reasons collars and tags can be problematic, certainly photographs for facial identification do not have the same kind of adverse health effects that microchip implants do.

Microchip technology has not been readily adopted by pet owners and the microchip special interests have been promoting mandates through pet shelter programs.  Best Practice (page 15) recommendations include methods for forcing mandates on the public through local ordinances and enforcing them through the shelter programs by refusing to release or return a pet unless it is implanted with a microchip.  Pet microchip mandates are generally imposed as a remedy for stray pets and many are mislead to believe it reduces euthanasia.  Most stray animals, particularly cats, do not have owners and are more often the product of overpopulation than pets getting lost.  The remedy to overpopulation is spay/neuter.  When pet overpopulation is controlled, there is minimal need for euthanasia and so it becomes less of a threat to a lost pet.

The adverse health effects of pet microchips on feral cats who are implanted actually creates a need to TNVR (Trap, Neuter, Vaccinate, Return) more cats for it to be effective for population control. There are multiple means of pet identification that do not cause pain, illness and exploitation.

Microchips mandates cause more problems than they solve.  In summary:

  • The pet microchip industry is essentially unregulated, making it full of risk and liability.  The safety of pet microchips is persistently misrepresented by the manufacturers and distributors.  Enforceable standards for safety do not exist.  Pet guardians are not accurately informed of the health risks.
  • Compliance with the mandatory microchip laws is costly.  Manufactures market risky microchips for field testing and low quality microchips at low cost to shelters and humane organizations trying to manage costs on a low budget, under mandates.
  • Pet overpopulation is best managed with spay/neuter programs and TNVR for cat feral populations.
  • Implanting a microchip in a pet:
    • is an unessential veterinary procedure that compounds risks and interferes with procedures for essential public health vaccinations and spay/neuter procedures that are essential to population control.
    • influences the individual circumstances of the pet, but does not substantially affect the bottom-line euthanasia rates of adoptable pets in communities where overpopulation is an issue.
  • Pet microchip mandates:
    • provide manufacturers with opportunity and protections to use our pets for nonconsensual experimentation as they can distribute unconventional, risky and harmful microchips,  without notice or labeling.
    • create a hostile environment for pets and pet owners who know the risks and would chose not to implant a microchip in their pet.
    • should include mandatory adverse event reporting and a liberal medical exception or otherwise be revoked.
  • Alternatives to microchips for pet identification exist that do not involve pet health risks, pain and exploitation. The key to good pet identification and retrieval systems is the registry.


There is a common belief that pet microchips are safe to implant in kittens as young as two months that weighs at least two pounds.  There is also a common belief that it is safe to sterilize a kitten at that age.  It has furthermore become practice to do these two procedures at the same time, particularly when there is a mandate for microchip implant.  Shelter animals seem to be the target of these procedures and many of the kittens and puppies are also at higher risk as orphans.  And they also need their vaccinations.  Little consideration appears to be given to the level of risks accumulating with all these veterinary procedures or elements of experimentation and cruelty.

The AVMA had originally recommended pediatric spay and neuter for population control reasons.  The health effects on the pet are controversial.  Their new recommendations for feline spay/neuter appears to be five months of age, with continued controversy.  No veterinary organization or source for recommendations to combine pediatric spay/neuter with microchip implant could be found.

The rapidly developing medical fields of inflammatory and auto-immune diseases  identifies the health risks of these procedures and how they promote disease.  Inflammatory and auto-immune illness is a valid basis for medical exemption from vaccination, including rabies.  The impact of too many procedures too soon may well be that our pets are not just less healthy, they may become less safe.

Trap, Neuter, Vaccinate and Return (TNVR) has become a proven means of reducing cat overpopulation.  As the cat is not just a predator, but is also prey in the wildlife system, consideration must be given in both respects.  Concerns over TNVR cats as predators have generally been disproved.  However, cruelty concerns about them as prey also exist.  Feral cats do poorly in captivity and must be returned as soon as possible after veterinary procedures are performed, even though they may still be vulnerable.  To add the unnecessary veterinary procedure of implanting a microchip to the more essential procedure of vaccination, spay/neuter and eat tipping leaves them more vulnerable as prey and raises cruelty issues.

The management of feral cat overpopulation is a daunting problem, just based on the shear numbers.  TNVR is most effectively targeted in areas where there is human/feline interaction.  However, the remaining population provides a reservoir of untreated cats that will fill any vacuum left by a treated feral that dies.  The additional health burdens of the microchip that reduce the survival of the feral, creates a need for more animals to be treated in order to manage the population.  Compounding the TNVR treatments with microchip implant is counterproductive.


The microchip risk/benefit is different for cats and dogs.  Stray cats can be pests but are not the same level of threat to public safety that dogs can be.  Cats are less conducive to ownership than dogs are and should be managed differently.

Cats do not get the same return to owner benefits from microchip implants that dogs do as they are 7-10 times more likely to find their own way home after being “lost” than dogs are.  That is another reason why TNVR is a good alternative to euthanasia for stray cats.  Microchip implant is not necessary and is even counterproductive to their survival.  After TNVR with an ear tip, they are best left alone unless obviously sick or in need of help.

The 2012 survey of approximately 1,015 pet guardians reported by the ASPCA shows that 43% of lost cats find there way home, while only 18% of dogs do.  The  survey shows 14% of dogs and 15% of cats may get lost in a 5 year period.  It also shows 92% of dogs and 74% of cats are recovered, leaving 2% of dogs and 3% of cats as lost and  not recovered.  22.7% of the lost dogs and 14.9% of the lost cats had microchips, but less than 13.6% of lost dogs and 1.4% of lost cats with ID were recovered.  That is a microchip recovery of lost dogs less than 60% and for lost cats is less than 10% with an overall pet recovery of less than 44%.

Some would still suggest that more cats would be returned if they were all implanted with a microchip, however, there is a much sadder explanation for the lower recovery rate.  Many more cats than dogs are killed in the roadway.  It is reported that 1.2 million dogs and 5.4 million cats are killed each year in the US on the roadways.  While these numbers include stray and feral animals besides pets, this more than explains the pets not recovered in the ASPCA survey and exceeds the US annual euthanasia rates of 0.67 million dogs and 0.86 million cats.

In the shelter, cats show fewer returns to owner than dogs do but the improvement claimed for microchip implanted animals in several studies is still quite similar, with 37% of cats returned and 30% of dogs returned that would not otherwise have been.  Is this an indicator of the system efficacy or the care and concern of the guardian of the pet?  Considering the UK microchip migration and failure rates of approximately 0.1%, that would point to the registries as the problem.   Are we to believe that 2 out of 3 people who lose their pet do not care to update their registry?


There is very little information on just how many pets get returned to owner because of microchips.   The available data is a little old and suggests only about 1/3 of lost pets with microchips are returned to their guardians who would otherwise not have been returned.  The 2012 ASPCA survey suggests a recovery rate of under 44% for lost pets with microchips.  Not all pets can be recovered.  HomeAgain reports that fewer than 50% of pet microchips are registered.

Failure of microchip tracking systems include:

  • Migration
  • Scanner Failure
  • Registry Problems
  • Chip Failure
  • Adverse Reaction

All pet identification system are limited in efficacy by their registries.  The key to recovery is to have an accurate registry database.  As a first step to registration, the pet owner must know the pet microchip transponder number and how it is registered.  Internet searches for transponder numbers can be done to find the latest lists.  The international registry should contain them all.

The American Animal Hospital Association (AAHA) Universal Lookup searches a database of information on which registry the microchip information can be found in.  A multitude of microchip registries have emerged with databases that are poorly staffed and maintained.  One microchip producer lists the flaws in the registry system.  Some registries are not even available by phone contact so if you have a problem you can fill out the web form and maybe they will (or not) get back to you before your pet has been euthanized.   Attempts by the  AAHA to unify the search has been only partially successful and is no better than the information contained in the many poorly maintained databases.

Pet microchips must be in a registry to be of use and the AAHA lookup is the commonly used way to find the registry for a lost pet.  Some may guess about what registry the microchip is in, by the first three digits of the transponder number, but it would be best for all pet guardians to check the information in the registry and the registry lookup system, to assure a lost pet is found in the minimum amount of time to avoid euthanasia.

There are claims that the AAHA Universal Lookup processes 5,000 searches per day, but in 2018 it was approximately 3,700 searches per day (1.4 million per year).  With approximately 184 million cats and dogs as pets in the USA, that comes to less than 1% of the pet population in a years time.  The 2012 ASPCA survey suggests that 3% of the pet population per year gets lost.  The AAHA data suggests low participation in microchip programs and registrations, but still does not tell us why.

Maybe it is the privacy policies.  Selling the volumes of pet owner data collected in registries is another way the industry exploits pet guardians.  The internet is full of stories of registries putting fees before pet recovery and their privacy policies are that you have none.

Microchip implant is a failed technology because microchips are made invasive and/or toxic to prevent migration and have other adverse health effects.  Registries are failures because they are being used to collect personal information, making them invasive of pet guardians privacy.


Conventional ID methods for cats and dogs include a collar and tag.

Some animals will have a tattoo.

Ear tipping of feral cats has also been done for some time as a means of identifying them.

Older microchips that do not conform to ISO standards may be missed with an ISO compliant scanner.  However, universal scanners have become available that can read them.

God gave our pets a unique identifier.  Yes, their loving noses.  Each dog and cat has a nose print as unique as our fingerprints.  Patents exist for nose print identification systems.  However, no active services appear to be currently available.  The Canadian Kennel Club has been accepting dog nose prints as proof of identity since 1938.

There are active registries for the facial recognition of cats and dogs.  The Petco Foundation sponsors Finding Rover .  There is also an app at Pip My Pet

With the facial recognition and finger (nose) print technologies of today, it is absolutely not necessary to use harmful invasive technologies to have permanent identifications of pets.  Their loving faces and noses are certainly more reliable than a microchip.

Microchip implant and registration is a failed tracking technology that has become abusive.  There is no excuse for mandating all our pets be subjected to the pain and health effects of the microchip.


Managing a stray and feral population, particularly of cats, can be a daunting problem.  They reproduce at rates that are way over sustainable levels.  Females reproduce themselves to death and most of their kittens do not survive.  Humans who try to rescue them flood the system with more animals than there are homes for.   Then comes the euthanasia of adoptable pets.

TNVR is currently the best remedy.  However, the shear number of cats that need to be treated are also a daunting problem.  Animal control agencies and rescue groups can be overloaded.  This is a community problem and a community that does not want pets euthanized must participate to solve the problem.

While government agencies favor mandates, fewer than 20% of pet owners want their pets implanted with a microchip.  Most people who aid ferals and strays would have similar views.  Those views are supported by the information we are posting on this site.   TNVR is most effectively targeted in areas where stray and feral cats interact with humans.  To achieve that, people must be comfortable with identifying cats for treatment. The needed community participation will not happen if there is a microchip implant mandate for these cats.  The recommendations to promote community participation to remedy lost pet and overpopulation problems are:

  • Pet Microchips
    • Mandatory microchip implant ordinances for the general population should be revoked to prevent problems from compounded veterinary procedures, conflicts with rabies vaccination, liabilities from experimental and risky products and obstacles to public engagement.  They should otherwise include mandatory FDA adverse event reporting and liberal health exceptions.
    • Microchip implants should not be promoted without informing the responsible party of the risks.   FDA Microchip Guidelines and compliance with  Veterinary Devices should be reviewed.
    • Any working microchip should be acceptable ID and a pet with such should not be implanted with another.
  • Registration and Public Engagement
    • Priority should be given to participation in pet registration and alternative ID should be accepted from pet owners who are aware of the health risks from microchip implants and find them unacceptable for their pet.
    • Facial Recognition (FR) should be incorporated into protocols for identifying lost pets. A digital FR photo could serve as ID in the registration database.
    • The facial recognition website FindingRover is free, offers partnerships and has adoption options.
    • Priority should be given to promotion for adopting and returning pets. A good facial picture for FR and a good full picture would promote returning lost pets and marketing pets for adoption.
    • Nose Print identification should be given consideration if the technology becomes available.
  • Public Safety and Population Control
    • Rabies vaccination should be given primary priority for public safety and sterilization given priority for population control.  Laws involving pediatric veterinary procedures should be limited and should not include pet microchip implantation mandates.
    • Rabies vaccination and spay/neuter compliance guidelines should match the current state of veterinary practice and owner beliefs and the registration database should automate progressive warnings of non-compliance with enforcement limits reasonable and clearly set.
    • TNVR and other spay/neuter programs should be the primary means of cat over-population control and priority should be placed on their vaccination, spay/neuter and ear tipping with microchip implantation discretionary as the last priority.  Cats need care and consideration following microchip implant for over three days and for weeks afterwards.   No one should be implanting them if they cannot provide the needed care.