All of my cats have had their teeth cleaned and, on occasion, extractions, too, w/no complications whatsoever. Perhaps your co-workers inlaws' cat had a condition that caused complications. Try not to worry about it. If your vet feels that there could be a problem, such as an upper respiratory ailment, s/he wouldn't do the cleaning. I'm sure your kitty will be fine. Please keep us updated. We'll send up prayers that all will be well for her and you.