New Mexico's Pet Resource WINTER 2008


by Nancy Marano

Recently I received a phone call from a worried friend. She’d heard reports on the news that microchips could cause cancer in cats and dogs. Understandably, she was concerned about the microchips implanted in her cats.

The current controversy stems from reporting done by the Associated Press (AP) and picked up by the New York Times, ABC News and others, about the VeriChip Corp. chip, designed to be implanted in humans. These chips allow doctors to access a patient’s medical records. The chips, which are about the size of a rice grain, are encased in a glass capsule and implanted in a patient’s upper arm. They are activated with an electromagnetic scanner. The chips are meant to be used in patients with various diseases as a way of providing necessary medical information to doctors.

The Food and Drug Administration (FDA) approved implanting the chips with a “reasonable assurance” that the chip was safe. According to the AP article, neither the company nor the FDA disclosed studies done in the 1990’s stating that chip implants “induced” malignant tumors in lab rats and mice. The studies also listed a tumor found in a French bulldog that appeared to be directly related to the microchip.

VeriChip Corp. points out the studies were flawed because the mice used were genetically predisposed to cancer and thus didn’t represent the general population of pets. They also say results in mice don’t always correlate to what happens in larger animals such as dogs or humans. Also, whenever a substance enters an animal or human subcutaneously, it can cause irritation or inflammation thus becoming a possible trigger for a tumor. This would include vaccines or foreign bodies.

The reason these news reports have upset many animal owners is because the chips used for humans are similar to the microchips implanted in their cats and dogs for identification purposes.

For the last ten years the British Small Animal Veterinary Association (BSAVA) and the World Small Animal Veterinary Association (WSAVA), have participated in an ongoing study in the United Kingdom where microchipping animals is required and over four million animals are microchipped. The purpose of the study is to determine adverse reactions in animals from microchips. This study has shown only two cases of cancerous tumors in ten years.

People who say microchips are possible cancer causing agents stress that animals who developed tumors did so within the first two years after implantation. They urge longer studies be done to determine the long-term safety of the chips.

Emily Walker, D.V.M., operates The Albuquerque Cat Clinic. When asked whether she has seen any cases of a tumor being caused by a microchip, Dr. Walker’s answer was emphatic. “I welcome the opportunity to debunk these irresponsible rumors. I have never seen a case of cancer caused by a microchip.  I have also never spoken to or met another veterinarian who has seen this. I absolutely recommend all cats be microchipped,” she said.

Dr. Craig Mabray, Director of Veterinary Medical Services for Albuquerque Animal Welfare, agrees. “Veterinary literature suggests that no correlation between microchipping and cancer exists.  And I’ve never seen it personally in my 25 years of private practice experience.” 

Microchips are an increasingly accepted way to identify pets. The chip cannot be lost, removed, damaged or worn out. It contains a serial number that positively identifies the animal. Owner information is accessed by reading the chip with a special scanner. A veterinarian implants the microchip with a needle in the subcutaneous tissue between an animal’s shoulder blades. Once implanted, it needs no more attention, according to HomeAgain, one of the major chip makers. The chips are a stainless steel material similar to that used in repairing bone fractures.

Identification microchips are passive. They send out no signals of their own. They can only be read by a scanner that picks up the information encoded on the chip. This encoding gives an access number when scanned. The reliability and ease of use connected with the chips has made them the main system of identification in animal shelters.

According to the Humane Society of the United States (HSUS), six to eight million lost pets are brought to shelters every year. HSUS believes microchips are like an insurance policy and provide one of the best chances that your lost pet will be returned to you.

Kat Albrecht is the founder of Missing Pet Partnership. This national nonprofit is dedicated to the research of behavioral patterns of lost pets and the education of owners about searching effectively. She advocates the use of microchips for identification, too. “Microchips are a safe, permanent form of identification allowing a pet to be traced back to the owner through a national database,” Albrecht says.

Albuquerque requires animals to be microchipped. The chip number must be sent in with proof of an animal’s rabies vaccination in order to get a city license. In 2007, 27,312 animals were brought into the Albuquerque Animal Care Center. For the first time more animals left the shelter alive than were euthanized. 14, 677 animals left the shelter alive and 11,968 were euthanized. While the euthanasia numbers are still too high, they are turning around. The hope is that even more lost animals will be returned to their owners because of the chips. Bernalillo County has proposed a change to its animal ordinance to require microchipping. Santa Fe does not require microchips but the shelter strongly recommends them. If an animal is adopted from the Santa Fe Animal Shelter and Humane Society, the animal can be chipped at cost.

Once the law requiring mandatory microchipping of pets went into effect in Albuquerque, lost animals with chips were recovered by their owners in greater numbers. Reclaimed animals who had chips went up from 33% to over 70%.  In December 2007 alone, of the 269 lost pets reclaimed by owners, 211 were microchipped.

“The return of a lost pet may well be worth any risk involved with implanting the microchip,” says Stephen Hopkins, D.V.M. of Albuquerque’s Academy Animal Clinic.

For cat owners like me who worry their indoor-only cats might get outside accidentally, having them microchipped provides an extra level of security. Should my cats get lost, I am more confident they will be returned to me if the shelter can scan their microchips and determine how to contact me. The thought of losing my cats is devastating. Getting them back would be priceless.

Nancy Marano is an award-winning author who is owned by two cats, Sammy and Rocky, and a Westie named Maggie May.

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