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Q. What is a microchip implant for animals?

A microchip implant for animals is a glass-encapsulated RFID microchip designed to be implanted into living flesh. The device consists of a Radio Frequency Identification or "RFID" integrated circuit (aka a microchip), a capacitor, and an antenna, sealed in a capsule of medical-grade glass.  Since the early 1990's, implants have been marketed and sold for use in dogs, cats and other pets, horses, laboratory animals, livestock, and wild salmon. The implant is designed to remain permanently embedded under the skin of the animal.

Q. What is the purpose of an animal implant and how does it work?

The implant is marketed as a way to identify animals. Here is how it works: a scanner is
brought within range of the implant, the scanner emits a radio signal that stimulates the
implant, causing it to emit its own radio signal in response. That signal is picked up by the
scanner and converted into a unique identification number. The number is used to identify
the animal or call up a related record.

Q. How many animals have received microchip implants in the U.S.?

In the last decade, millions of wild salmon have been implanted with RFID microchip
devices to track their movement through waterways. Countless laboratory animals have also
been implanted, and many farm animals across the world are being microchipped, as well.
Close to 5% of the United States' estimated 164 million dogs and cats have microchips in
their flesh. Animal shelters around the United States routinely chip pets before releasing
them for adoption. In addition, governments, including those of Los Angeles County, and El
Paso, Texas, have passed ordinances requiring that all dogs under their jurisdiction be
microchipped. El Paso has extended the chipping mandate to cats and ferrets.

Q. Can the microchip help locate a lost pet?

Not in the way many people think. The microchip implant does not have GPS capability to
locate a missing pet, nor does it use a satellite. The read range of a microchip implant is only
3 to 12 inches, so a scanner would have to be very close to an animal to read the implanted chip. A microchip implant can help recover a pet if and only if the pet winds up at an animal shelter or a veterinarian's office. When shelter staff members find a stray animal, they first check to see if the animal is wearing a collar. If there is no collar, workers run an RFID reader over the animal's body to look for a microchip implant. If the pet has been chipped, the implant will emit a numerical code that can be looked up in a registry to identify and contact the owner.  Because the scanner must be brought very close to an animal in order to read its RFID implant, the implant would not help find a pet that has been lost in the woods or gotten loose on a city street.

Q. Are there different brands of pet microchips?

Yes, there are four main types of microchips that have been marketed for use in pets:
_ ISO Conformant Full-Duplex chip2
_ AVID Secure/Encrypted "FriendChip"3
_ U.S. HomeAgain®, AVID "Eurochip": or FECAVA4   
_ "Trovan Unique" and Current AKC CAR chips5

These chips are generally incompatible. One type of reader may not be able to read a
competitor's microchip. However, some scanners can read multiple chip types.

Q. Have implanted microchips caused cancer in animals?

Yes. In a series of scientific studies published between 1996 and 2006, researchers found a link
between implanted microchip transponders and cancer in laboratory animals. Between 1% and 10% of mice and rats implanted with the chips for identification purposes were later afflicted with sarcomas, fibrosarcomas, and other invasive cancers surrounding or attached to the implants. The fast-growing, malignant tumors often metastasized (spread) to internal organs, lymph nodes, and musculature and frequently resulted in the death of the animals.   In two confirmed cases dogs have also developed cancer surrounding or attached to microchip implants used for identification purposes.
Photo of microchip-induced tumors


Q. Where did the tumors form in the animals?
In all cases, the cancerous tumors were located at the site of the microchip. The tumors either
encased the microchip or were immediately adjacent to it. When scientists examined the tumors
microscopically, they found that the tumors originated in the capsule of tissue that formed around the microchips.

"All tumors were or near the implantation site...[the tumors] were attached
to the implant or partially or totally encased the implant."
_ Palmer et al. on their 1998 study that found malignant fibrosarcomas in 2% of 800
mice studied (p. 170)

"The intact microchip was found completely embedded within the [malignant] mass." 1
_ Vascellari et al, from their 2004 study that found cancer in a dog (p.188)
Numerous other studies reached the same conclusions.

These studies, detailing the formation of cancer surrounding microchip implants, are described in detail in the comprehensive comprehensive review of the research titled "Microchip-Induced Tumors in Laboratory Rodents and Dogs: A Review of the Literature 1990.2006." (Click here to read the full review)

Q. How does the microchip implant cause cancer?
Researchers have proposed several explanations for the cancerous tumors found around
microchip implants in animals, as follows:

(1) Foreign-Body Tumorigenesis: The presence of a foreign body under the skin may cause
cellular changes that lead to cancer.
(2) Post-Injection Sarcoma: Inflammation from the chip-injection procedure may give rise to

(3) Possible Genotoxic Properties of the Implant: The microchip may have carcinogenic
properties or cause the body to produce carcinogenic byproducts.

(4) Radio-Frequency Energy Emissions from the Transponder or Reader: The radio -frequency energy involved with the device may contribute to tumor formation.  Each of these hypotheses is addressed in greater detail in our comprehensive report on the
research titled "Microchip-Induced Tumors in Laboratory Rodents and Dogs: A Review of the
Literature 1990.2006."(Click here to read full review).  However, we currently don't know which, if any, of these hypotheses is correct.

Q. I'd like to examine the evidence myself. Where can I find the original research studies?

 The studies were originally published in a variety of pathology, veterinary and toxicology journals between 1996 and 2006. The author of this FAQ, Katherine Albrecht, Ed.D., has authored a comprehensive, 52-page report titled "Microchip-Induced Tumors in Laboratory Rodents and Dogs: A Review of the Literature 1990-2006." Click here to read the full report.


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