I assume you mean prescriptions for the human pill form without all the paste chemicals. Asking for a doctor to prescribe the large mammal paste is as silly as asking a doctor to write a prescription for a flea/tick collar.
Next best thing is walk over the Southern border with the illegals and just buy the stuff from a pharmacy down there, it's cheap and plentiful
What a laugh. the "paste chemicals" are an inert carrier. It's as edible to humans as it is to animals.