They told me he kept messing with them while he was in recovery: he'd appear to be sleeping, but he'd wait until someone leaned over to check the dog in the cage underneath his, and then he'd let out the loudest MAO -- which would startle the attendant into banging her head on the shelf. Apparently, this happened multiple times and to more than one attendant. The vet staff said, "It's almost like he did it on purpose... haha." Almost, hell. They don't know The Z.
I was pretty sure the little guy wasn't ready to cash in his cat chips just yet. Thank you to everybody who sent good thoughts and prayers for him -- it made all the difference and I finally heard him purr back tonight. :)