Why avoid Microchips?
                  Horses have developed problems as a result of having microchips implanted into the nuchal ligament of the neck. 
                  1.  Foreign object: First and foremost is the fact that a microchip is a foreign object. No one should          be forced or coerced to implant a foreign object in their horse.
                  DNA samples, Tattoos and Brandsare the best options for ID. 
                  2.  Health risks: Animals have developed infections, abscesses and          lumps because of microchip implants.
                  http://www.invisio.nl/antichip/BriefLaarakkerenconfr.pdf
                  in English http://www.invisio.nl/antichip/tekstlaarakkereng.htm
                   Also, a pattern that has been observed in some microchipped horses is that they have difficulty bending their neck to the left.  (The designated site to implant a microchip in a horse is in the nuchal ligament, on the left side of the neck).
                  3.  Migration of implanted microchip: The microchip implant can move          from the original implant site.  Movement of the device within the          body can cause health problems for the horse.  When microchips move          around in the horse’s body, it also becomes difficult to locate and,          therefore, read the implant.
                  4.  Loss of microchip implant: In addition to being “lost” within a          horse’s body, a microchip implant can be expelled from a Horse's body.
                  5.  Failure of microchip implant: For a variety of reasons, implanted          microchips simply do not work.
                  6.  Failure of electronic scanner: For a variety of reasons, scanners          cannot read, or even detect, the implants all of the time.
7. Magnetic resonance imaging (MRI) incompatibility: One of the          problems of using microchip implants with MRI machines is that the          implant can impede MRI diagnostics.  The authors of a Japanese study          write, “There was significant signal loss and image distortion over a          wide range around the area where the microchip was implanted.  This          change was consistent with susceptibility artifacts, which rendered          the affected area including the spinal cord undiagnostic.”
                  8.  Lifespan of the microchip: According to pet promotional          literature, the microchip implant lasts the lifetime of the pet.          However, it is a vague answer to a specific and important question.          Human data also fails to provide a precise answer.  In 2004, Angela          Fulcher, vice-president for marketing and sales of VeriChip          Corporation (now known as Positive ID), said, “We believe the tag          [implantable microchip] can last for 20 years.”  Other reports,
however, indicate that the average lifespan of a microchip implant is          10 to 15 years.
                  9.  Temperature-Sensing microchip implant:  Microchip implants that          are supposed to be able to read a horse’s temperature have also been          sold.  However, according to promotional literature by Destron          Fearing, a wholly-owned subsidiary of Digital Angel Corporation, the          temperature-sensing microchip implant is not accurate. In extra fine          print it says:
                  
                    Conclusion:  The study horse’s actual temperature will be 3º higher                        than Bio-Thermo readings.  Knowing this, the horse’s manager or                        veterinarian will be able to quickly and easily identify if the                        horse’s temperature is abnormal by adding 3º to the Bio-Thermo                        reading.” 
                    
                  This means that important health decisions could be erroneously made based on this inaccurate reading that is already known by the
manufacturer, revealed in "fine print".
                  Manufacturing and selling temperature-sensing microchip implants that                    cannot even read a horse’s temperature accurately is simply unethical.                    Why would anyone trust a company that operates in such an unethical                    manner?
                  10. More risks: The United States Food and Drug Administration (FDA)          also lists failure of insertion device, electromagnetic interference,          compromised information security, electrical hazards and needle stick          as other risks associated with microchip implant technology. Read Document Here
                  11. Cost: Breeders are required to have a working microchip          scanner on the premises?  If so, it is another $250+ investment to          purchase a reader. Readers are specific to each microchip, so even if your Horse is lost, the microchip will not be readable unless the matching Microchip scanner is available to read it, and as long as the attendant can find the microchip (in case of migration).
                  12. Cloning microchips and the integrity of microchip numbers: 
                  Microchip implants can be cloned, and even infected with computer
                    viruses and worms. 
                  Also, a recent document by Virbac Ltd UK says there are microchips
                    with a prefix of 978 that are currently on the market that clients may                      believe are Virbac’s chips.  However, the microchips do not belong to                      Virbac and the company says it is not liable for any problems caused                      by these chips.
                  It is also important to be aware of the fact that microchipping kits
                    are being sold via the internet.  For example, EBay Germany sells
                    microchip kits.  So, how are consumers supposed to know if microchip                      numbers are valid, if the insertion device and microchip are sterile                      etc …?
                  13. Scientific data shows that a variety of species have developed cancer                    because of microchip implants.  we should be especially concerned about                    implanting a potentially carcinogenic object into our horses. (see list of studies below).  
www.ncbi.nlm.nih.gov
                  www.vetpathology.org
                  www.antichips.com
                  www.antichips.com
                  www.ncbi.nlm.nih.gov
                  veterinaryrecord.bvapublications.com
                  www.ncbi.nlm.nih.gov or www.antichips.com
                  www.aipvet.it
                  aalas.publisher.ingentaconnect.com
                  www.ncbi.nlm.nih.gov
                  www.ncbi.nlm.nih.gov
                  www.acvp.org or  vet.sagepub.com
                  www.eurotoxpath.org
                  veterinaryrecord.bvapublications.com or www.nal.usda.gov
                  www.ncbi.nlm.nih.gov
                  www.sciencedirect.com
                  www.ncbi.nlm.nih.gov or www.antichips.com
                  www.ncbi.nlm.nih.gov or www.antichips.com
                  www.ncbi.nlm.nih.gov
                  vet.sagepub.com
                  www.ncbi.nlm.nih.gov or www.antichips.com