I don't totally know what it was. She just became unresponsive, and she was making a "clicking" noise, with some twitching/shaking. It only lasted maybe 30 seconds, and then she was fine. I stood her up, and she had no balance issues, and her pupils were fine. The only difference was that she was breathing a little heavier. She actually is scheduled for a rabies booster on Friday, so I am going to bring this up to the vet. Does it seem like it was a seizure, or a stoke of some sort? She is 8 or 9yrs old, spayed, and has been an indoor cat her entire life. eta: Could she just have been in a deep sleep and had a nightmare type of thing? She was laying down at the time, but I wasn't paying much attention to her until the clicking. I did shake her, but she did not wake up during that time. Might she have been in a REM sleep and just did not register me shaking her?