Used as a pet identification method, the microchip is implanted under a cat's skin. Unlike a collar, a microchip implanted in your cat will never fall off or get ensnared on a branch or fence. Though the chance of side effects is uncommon, occasionally a cat will experience some minor bleeding at the chip implantation site. In rare instances, the microchip may migrate elsewhere on the body.
How the Microchip Works
Picture a large grain of rice and you get the idea of the size of a microchip. Housed in a glass cylinder, that tiny chip is actually a transponder, emitting radio waves when a scanner of the proper frequency passes over it. The chip contains an alphanumeric code, which is transmitted to the scanner and displayed on a screen. The identification number is tied to a database containing the pet's and owner's contact information, allowing an animal shelter, rescue organization or veterinarian to search the code in the database to return the pet to her owner.
A microchip does not take the place of a rabies vaccination tag or an identification tag; it only contains an identification number. It is important for the pet owner to ensure that contact information is current in the microchip manufacturer's database.
Implanting a Microchip
The microchip is implanted under the cat's skin with a hypodermic needle that's large enough to contain the chip. The vet usually doesn't use anesthesia for the procedure because it's not an invasive or particularly painful experience; implanting the chip is similar to getting a vaccination, and any pain or discomfort is short-lived. If the cat is going under anesthesia for another reason, such as a spay or dental procedure, the microchip can be implanted then, sparing her any discomfort.
If you are concerned about any pain your cat may feel from a microchip implantation, discuss using a local anesthetic with your veterinarian.
Immediately after injection, your cat will feel a bit of discomfort, much as she would from a shot. She may experience minimal bleeding at the injection site, a possibility from any shot. Microchips are coated specifically to avoid triggering inflammation, so it's rare for a cat to become sore or experience swelling at the injection site. It takes a couple of weeks for the cat's tissue to heal around the chip to hold it in place, so occasionally a chip will migrate through the tissue and end up somewhere else. The American Veterinary Medical Association reports other potential low-risk side effects, including infection, hair loss and microchip failure.
The American Veterinary Medical Association notes that microchip migration is the most common side effect of microchip implantation. Take your cat to the vet to be scanned weekly until the vet is confident the chip is permanently in place so you know where the chip is.
Microchips and Cancer
Laboratory mice have shown a tendency to develop tumors at chip implantation sites in studies. The American Veterinary Medical Association states that microchip-associated tumors were reported in two dogs, in 2004 and 2006, and a microchip-associated fibrosarcoma was discovered in a cat in 2011. Currently, there is no evidence that microchips cause cancer in cats or dogs.
If you are concerned about the potential side effects of a microchip, consider the benefits versus the risks. Though there is no guarantee your cat will be reunited with you because of a microchip, a microchip greatly improves the chance a lost cat is returned to her owner. If your cat spends a lot of time outside and has a tendency to wander, a microchip may be a worthwhile investment.