Surely some stand-up comedian has made this joke already

Yesterday, my cat had a checkup at the vet, and was found to have an ear infection. So now I have to put drops in her ears every day for three weeks, a process she does not enjoy.

The sheet I got from the vet's office says that one of the possible side effects of the medicine is "drowsiness." She's a cat. How am I supposed to tell if she's suffering from drowsiness?