I was trying to figure out how rodents were going to help here. . .

They don't teach liquid dosing common sense in medical training programs. When I prescribe a liquid medication, I calculate the amount needed plus a small margin of spillage/stick to the side of the bottleage error. But I'm a pediatrician and most of our meds are liquids. And I'd rather do the math at the outset than field the phone calls later.

Your letter should truly be sent to this clinic so they can pin it up as a practical lesson - "here's why we made you take arithmethic"