can anyone help or tell me what happened

[Tad Carlucci]

It happens. It's a bug .. IIRC, it's an old, worn-out bug which Linden Labs is unlikely to ever fix.

Waiting a while and logging back in are the recommended self-correction actions. You don't need to try another viewer.

At this point, you should file a support ticket. They're usually pretty quick about sending a replacement. You will need the cat's UUID, which you can obtain from the Pedigree pages.