Visiting Veterinarian : Leaving tracks

By Michelle Gerhard Jasny V.M.D.
Published: May 8, 2008

It was late afternoon, a cold February day in the early 80s. I was taking a solitary walk along Lake Tashmoo, strolling past deserted houses, watching the sunset reflect in the icy water. Roused from my contemplative mood by a sudden whistle and rustling of leaves, I looked around curiously. There was John Rogers, the Tisbury Animal Control Officer (ACO), traipsing through the woods. We stopped and chatted. John had been coming to the lake for hours every day looking for a missing dog. We are so lucky here on the Vineyard to have the kind of ACOs we have. They know the community. They know our pets. They often go door-to-door trying to locate the owner of an animal. Our MSPCA shelter, too, is exceptional in the efforts made to reunite pets and people. For years if I had a stray animal, I would call these good people. The conversation might go like this.

Me: "I've got a fat female golden retriever here with a red collar, no tags." ACO: "I bet that's Mr. Whosit's dog. He called me this morning to say she ran off." Or Me: "I've got a hit-by-car cat. Got any listings for a neutered male black and white domestic short hair?" MSPCA: "Does he have a kink in his tail? I've got a listing for a black and white tom with a kinked tail." Me: "Wait, I'll go check...nope, no kink...but there's a white patch on his chest shaped like Texas." You get the idea. Back then, if you wanted Rover to have permanent identification, a tattoo was your main option. Most people just wrote a name and phone number on the collar, or ordered an engraved dog tag. By the mid-80s, we began to see the advent of the microchip for pet identification. I was slow to jump on the bandwagon. "It's a small Island," I said. "If Rover gets lost, he's going to end up with the ACO or MSPCA." A responsible pet owner could find out easily if Rover had been located by simply calling the shelter, the ACO, and both veterinary practices. Yup, there were only two in those days.

But the Island grew. More people, more pets. People were traveling off-Island more with their animals. Some were even going abroad. A microchip could help a veterinarian, ACO, or shelter worker locate an owner in a more timely way. It might be the difference between life and death. I decided to buy a microchipping system. Lo and behold, I discovered that a huge legal controversy over patents had just arisen, the outcome of which could impact which microchips continued to be marketed. I opted to wait until the court battle subsided.

Years passed. Vineyard pets continued to be lost and found. I tried again to pick a microchip system. The patent battle had been settled, but a new controversy had arisen. Europe uses a different frequency microchip than the United States. In a move to standardize, a new chip using the European frequency was being marketed here, and used by one of the country's large veterinary chains, as well as some humane organizations, and all of Canada. Why should this matter? Because the scanners used to read the different frequency microchips were not interchangeable. I wanted to be sure that if Ranger got a microchip at my office, it would help him find his family whether he got lost in Edgartown, Edmonton, or England. I opted to wait until the battle over frequency and scanner technology was resolved.

Then this spring a salesman arrived with yet another microchip sales pitch. I was tired of referring my clients to other veterinarians to get microchips. The discussion over frequencies and universal scanners hasn't been settled, but progress has been made. It was time for me to take the plunge. But which system to buy? Each had pros and cons...and it wasn't just about the chip, or even the scanner. It was also about which database and retrieval system was most reliable. The American Kennel Club used to recommend a specific brand, but recently terminated that alliance. One company abruptly changed their policy, from lifelong service after initial registration, to now include an annual fee to owners. That didn't seem fair. I polled the other Vineyard veterinarians and MSPCA. If the majority used one brand, then I would follow suit. No such luck. Different brands all around. I picked the system that seemed best to me, took a deep breath, and ordered.

The following Monday I microchipped my first patient, a stuffed animal. The needle looked really big but luckily my patient was stoic. That puppy now sits on our reception desk to announce that we now offer microchipping. On Tuesday I microchipped a live dog. On Wednesday I revised my surgical release forms to include the choice of microchipping during neutering. On Thursday I mentioned the option to the new owners of an adorable Croton puppy. They were interested but told me they had recently heard that microchips might cause cancer in dogs.

"Well, I might be more concerned with cats," I responded slowly. "We know certain genetically susceptible cats can develop tumors from anything that causes irritation. Let me check it out." I went to my on-line veterinary service and typed in a search for "microchip and cancer." It would be just my luck if I held out through patent lawsuits, frequency controversies, and database upheavals, only to order my microchip system just as they discovered an associated cancer risk.

Here's what I learned. There have been an extremely small number of isolated reports of tumors growing near or around microchips in dogs, and one reported case in a cat. These "single incident" cases provide no way to test for, or prove, cause and effect. Millions of dogs, cats, and horses have been microchipped for almost two decades with no adverse effects. It is true that a number of studies show that microchip implantation may cause cancer in mice, but many of these protocols were flawed, and mouse models cannot always be extrapolated to other species. Last year an uproar was generated by a widely circulated article called "Implanted Microchips Cause Cancer" by Jane Williams. The article lumped bits and pieces of various studies and sources together, but did not use good scientific method to evaluate and interpret the data. Within the veterinary community, people are keeping an open mind, but few think it is a significant concern. As far as we know there is absolutely no proof that microchips cause cancer in dogs or cats - or people, for that matter.

Even if it were true that, in rare instances, microchips may be implicated as a factor in tumor growth, the key point really is risk assessment. The odds of a microchip causing a problem are undoubtedly far smaller than the odds of Ranger getting lost, and the microchip saving his life by identifying him and reuniting him with his owner. Every day we have to weigh risk against benefit. Vaccinations on rare occasions may cause serious allergic reactions, but most of us believe that the benefits of preventing deadly diseases far outweigh the risks. I heard recently that more people die from being hit on the head by falling coconuts than by shark attacks. I am undaunted. Any time I get a chance to visit more tropical climes, I live dangerously. I walk beneath the swaying, coconut-laden palm trees. And I plan to microchip my dog.