I think I would send her an email that begins and ends with compassion for the kitty. Type it out, and reread it the next day.

You can't CHANGE her. You don't want to alienate her, necessarily. So, if you do it with compassion, and facts, that is the best, and all, you can do. After that, you run the risk of offending her, and losing any other opportunity to educate her.

Sometimes we see it as a 'either/or' situation. If it doesn't work now, maybe it will work in six months.....