As I was reading through a thread about Louis getting MA pregnant, I stumbled upon the theroy of Louis having an operation "down south" which tickled my interest.

Please correct me if I'm wrong but wasn't general anesthetic, or even an effective local anesthetic, unavailable untill early - mid 18oo's? Frankly, I find it hard to believe that Louis, or anyone for that matter, would have an operation of that sort.
Does anyone have any information about the use of anesthetic in that time period?

I also read something about breast cancer operations in the 18th century. Has this topic been addressed? Does anyone have any links relating to it?

The fact that some operations were excruciatingly painful doesn't mean they weren't necessary. Want to have fun, read a period description of a breast cancer operation. Yes, Louis XVI was "adjusted" intimately. And Louis XIV as I recall had an anal operation which was no fun either.

All without anesthetic, yes.

They had opium in the 18th Century, which they gave in the form of laudanum. It didn't knock the person out, but it helped. There was also alcohol, and many people were dosed up with that, especially soldiers undergoing an amputation. Soldiers probably passed out from the pain, which was just as well.

John Adams' daughter Nabbie underwent breast removal surgery for cancer, and she was given laudanum. The surgery was successful, but the cancer returned a couple of years later, and she died from it.

Anesthetics for childbirth didn't come into vogue until Queen Victoria's time. She was enthusiastic about it.