Yeah, I'm worried about that, too. Bo has had a collar on (he used to be an indoor/outdoor cat) but Abby and Hanna have never had one on.

I wanted Hanna to get microchipped when she got spayed, but the wires got crossed in my instructions and they didn't do it. I didn't want to have it done when I picked her up from the spay - I figured she had been through enough and I'll probably have it done when she goes in next year for her shots. I read some pros and cons about microchipping, and one of the cons is that there are still a lot of vets/animal shelters that don't always scan for chips. I'll probably have it done anyways, hopefully to all three cats.