Losing a dog can be a nightmare. If your dog goes missing you will want to utilize every possible resource to help assure his return. Dog tags can be read by anyone, and they are the most basic way to return an errant dog to his family. However, collars can slip and tags can fall off. A microchip therefore can be highly useful as a backup.

Microchips, of course, cannot be read by any random stranger who finds a lost dog. But in this day and age virtually every veterinarian and shelter has and uses microchip scanners. I personally have used microchips to return dozens of lost dogs to their owners after they were brought to my work place by Good Samaritans.

Therefore, one might suspect that my opinion of microchips would be entirely favorable. Indeed, when things go as they should, I believe that microchips are fantastic. However, you’d be stunned by how often things do not work as they should.

Let’s first clear the air about something: Do microchips cause cancer, or serve as a source of infection, or migrate malignantly around in the body? No. Microchips have been widely used for several canine generations. We’d know by now if they caused medical problems. There will always be conspiracy theorists and activists who believe that microchips are dangerous, just as there will always be people in Pakistan and Nigeria who believe that polio vaccines are a plot by the West to sterilize the local population. To date I have seen no evidence that microchips are associated with medical harm to dogs.

So, how can things go wrong with microchips? It’s not the chips that are the problem. Trouble comes from the people to whom the chips sometimes are registered.

The following scenario has played out many dozens of times in my career. Animal care and control is called after a dog is hit by a car. No owner is in the vicinity. The dog is injured and has no tags or visible identification. The humane officer brings the dog to the emergency clinic where I work. A staff member scans the dog and finds a microchip.

Here is what should happen next. The staff member calls the microchip company and obtains information about the person to whom the chip is registered. That person is then called; the person, who had been frantically searching for his missing dog, rushes to the hospital to claim ownership of the dog and to assume responsibility for medical decisions (and payment) in the case.

What should happen does sometimes happen. But you would be stunned by how rarely it does.

Fifteen years ago, dogs generally only had microchips if their owners had purposefully had them implanted. A microchip was generally a sign of a responsible owner. Now, however, almost no dog leaves a shelter without a microchip. Plenty of irresponsible people now own dogs with microchips. And although responsible people sometimes lose their dogs, I can assure you that dogs owned by irresponsible people are more likely to be brought to my clinic by a humane officer.

Thus, with appalling frequency my staff member contacts the microchip company and discovers that the chip is not registered (which means that nobody bothered to submit a registration). Or we obtain owner information that is obsolete. (“That’s not my dog anymore. I gave him to my cousin’s wife’s friend’s brother two years ago.”) Or we contact the registrant, and he or she is too lazy, drunk, or stoned to come to the clinic. Seriously.

Cases get especially complicated when the registered owner of the microchip refuses to come to the clinic to claim ownership of and take responsibility for an injured pet. In many of these sorts of cases, the registrant tries to give orders about how to treat the dog over the phone (although they’re rarely so forthcoming with a means of payment). Sometimes they try to tell me to put the dog to sleep sight unseen.

Here is the issue: Only the owner of record can make medical decisions about a pet. When a stray dog is brought to my office by humane officer, the local humane society is the owner of record by default. Medical decision making power generally only can be transferred after an owner comes in person to identify the pet. Many folks believe that registration of a microchip ispo facto proves ownership of the dog. In fact, that is not the case.

Note that throughout this article I have referred to registered owners of microchips, not of dogs. That is because, legally speaking, microchip registration is nothing more than a product registration with a marketing company. In the eyes of the law, registering your dog’s microchip with Home Again carries no more weight than registering your refrigerator with Sears. That registration, combined with other evidence of ownership such as dog licenses and veterinary receipts, might be enough to satisfy a court of law in the event of an ownership dispute. But microchip registration on its own does not prove ownership of the animal. In fact, it doesn’t prove anything at all.

As I’ve mentioned, I have seen many cases in which the information registered to the microchip was out of date or obsolete. I also have seen outright maliciousness. In one very memorable case, a woman gave her dog to an acquaintance. She later had a falling out with the acquaintance, and spitefully (and falsely) reported the dog as stolen to the microchip company.

What does all of this mean to you? Microchip registration generally only goes awry when irresponsible or spiteful people are involved. Readers of Dogster generally are responsible, and for folks like you microchips offer a wonderful means to help reunite you with your pet. I am happy that my pal Buster is microchipped. If he were missing I would be desperately hoping for a call from someone who had scanned his chip. And for the life of me, I cannot understand why so many people don’t feel the same way.

Learn more about dogs with Dogster:

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• Be Polite to Your Dog — It Benefits Both of You

Got a question for Dr. Barchas? Ask our vet in the comments below and you might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)