Sheesh, you don't need a prescription. Go to Tractor Supply or any farm supply store. Get the version for "cattle and swine"--it's just a clear gel. You can put it in juice. It's not even bad straight, just wash down with plenty of water--or vodka, if you prefer.
It works as a preventive, and I've also seen it work as a cure--making symptoms start disappearing in a couple of hours, and complete cure within a couple of days.
It's used on a mass scale for human beings against various parasites, including river blindness. The Japanese inventors got a Nobel Prize for it.
The way I understand it, starting June 1st you must have a vets RX to get ivermectin from feed stores. Check it out, our government is so screwed up.