Let's look at some facts instead of flying off the handle with emotional doomsday reactions.
First, the chips are encased in a glass tube, sometimes with a plastic 'anchor' on one end. These materials are biocompatible.
The chip does not touch the critter. I does not have a battery. It does not send out radio signals. It is passive.
The only time it does anything is when a scanner signal of the right frequency is picked up by its internal antenna. Only then does the energy of the signal allow the chip to send back an identifying signal.
This is most likely a coincidence and a lawyer trying to make himself and his client a lot of money.
Here's a chart showing the 'adverse reactions' to RFID in pets. And this is with over 4 million of them in place. This is from the AVMA website.