Maybe Cleo is just devious then, because she not only fights like crazy but eats *around* hidden pills. She also somehow spits out pills, and can squirt liquid meds out of the corners of her mouth. Very literally too smart for her own good. With the powder, there's nothing for her to eat around!
Anytime we come up with something that works, one or two attempts later she has figured out how to thwart it. The mortar and pestle is finally Cleo proof. We're still working on giving her subcutaneous fluids more easily though.