I think negative stories about microchipping are being passed by the commercial breeder lobby. Since many states are requiring this, stories of the harmful effects will spread over the internet. The truth of the matter is they don't want to spend another $20.00 a dog, they much prefer tattooing, that way, they can identity their dogs, but no government agency can if it turns up abandoned. This is one of the safest procedures there is, and I've read the studies, involved with linking microchips and rats, and you must remember that rats are tumor-making machines and information gathered on rats and tumors does not always cross species. I would advise you not to microchip a rat though. I think I've read one study of a dog that had cancer, but this was in Russia, and many other things could have contributed to the cancer. Your chances of recovering your dog if chipped are so much greater, if someone finds your dog, all they have to do is take it to the vet, and they can notify you. Read this thread before you make up your mind against it.
http://www.yorkietalk.com/forums/gen...rch-yoshi.html. To answer your question, yes, Joey is microchipped, we got it done when he was neutered, and I feel much safer.