Broken Chip?

Post 501.  Let's keep going!

Here's a question from Esther...

I found your microchip blog posts and have a question for you:
Have you ever had seen or heard of a case of a chip (AVID) breaking up into two parts and one part migrating?

I just found a tiny lump on my cat halfway doen his back (about 5 inches from the original implant between his soulderblades, which is still detectable) and it feels just like a microchip! I took the cat to the vet and she agreed that it felt like a chip. Also, both sites scanned and displayed his AVID#!(NOT two different numbers, so it does not appear to be a chip that might have been implanted into my cat before I found him, when he was an unneutered, hungry stray.) Now, I suppose the scanner could have picked up the chip located 5" away from the site of this new-found lump.

My vet did not have any other idea what the lump could be ("I have never felt anything like it.") and recommended having it surgically removed to find out. (The lump is too small and too movable for a needle biopsy to make much sense.)

I will porbably follow her advise and have his teeth cleaned while he is under anesthesia. Still, I would like to find out first if there is a possibility of this being (part of) a migrated chip. Would it still scan if it had broken in two?

Thanks for your thoughts on this (if any)!

Yes, I know this is more fodder for the anti-microchip crowd, but I thought it was worth bringing up.

First, this is not a common problem.  Chips migrating are known, though uncommon, but a broken one is much less common.  Theoretically a broken chip could continue working, though it would be much more susceptible to damage.  The outer shell of a microchip is essentially protective, allowing it to be inserted without the inner workings making direct contact with the tissues. It's usually a sterile, non-reactive glass and has small holes for fibrous tissue to adhere to, therefore reducing the risk of migration as scar tissue "locks" it into place.  The smooth surface makes it slide into the tissues easily, allowing less trauma during implantation.

Since the outer casing serves no direct function in the chip's working once implanted, I could see a situation where it breaks or comes apart.  The casing and the inner parts could migrate to different locations, resulting in two different "lumps".  If there isn't too much trauma in the area, the actual working parts could continue functioning without the shell, allowing it to broadcast the chip number.  However, it would be much more likely to fail in the future as those parts would be much more easily damaged.  It's also very possible for a microchip's broadcast to be picked up several inches away (especially with 134 kHz chips), so you may be getting one signal from the chip and not in two locations.

I would agree with your vet's advice that it's worth surgically exploring this.  If it is the chip, I would recommend removing it and have a new one implanted (yes, I still advocate microchips and use them in my own pets).  Leaving it in place could lead to tissue irritation in the future or the chip could stop working.  If it's not the chip it sounds unusual enough to be worthwhile removing.

Good luck, Esther!