Yes, microchips can migrate, especially if they are not injected into the proper tissue layer. Most vets have scanners, as do animal shelters. I suspect my vet's office would do a scan on my dog, just as a courtesy. Whether it's migrated or not, you'd probably want to check out a mass on your dog's leg, even though the chances are it would benign.

Thanks Calliope - in the last 2 mths alone I've spent over $600 on vet bills; first he ate a whole corn on the cob and then he got over that and then he licked his paws to the point one was infected. Then he needed his annual check up..... oye!

So I'll call them and see if they can just take a look and see if it's the chip that relocated or if it's a tumor. Keeping my fingers crossed that it's the chip.