Why is my cat blinking?

Solution 1:

The way you've described the problem, the best bet is that it's continually switching between standing and prone. My first guess was that you actually have two cats on the same tile, one beneath the other, but then you'd get the spinning green line as it switched from one to the other. So that's not it.

As for WHY it's continually falling over, I'm not sure we have enough information. Cats don't eat or drink, so it's not collapsing in hunger or thirst. Extreme pain or missing limbs would appear in the view unit -> wounds menu. They probably will NOT appear in the view unit -> ztatus screen, because animals don't produce diagnosis tasks when they're wounded.