On the episode where the townsfolk get Anthrax, Charles and a friend run off to get meds for the towns people.
What could they have been getting?
Antibotics were a long ways off.
Suspension of disbelief.
Whether or not they could do anything, it is just human nature to try. Would you rather that they sat around and said “Well, I reckon you’re gonna die.”
There were all kinds of medicine for all kinds of ailments. Sure, they didn’t work, but humans can be a little dense. Remember how long it took us to realize that bleeding people wasn’t a good idea.
My WAG is that they were fetching alcohol to dull the pain, and perhaps something to try to make breathing easier. At that time they had medicines that could begin to alliviate symptoms and discomfort.
Can you say powdered rhino horn? I knew you could! 
There’s definitely nothing about anthrax in any of LIW’s books, so I’d put it down to poetic license / shoddy research on the part of the TV scriptwriters.
wasn’t quinine given for everything in the pre-antibiotic days. I’m not saying it would have worked, just that people might have tried it.
Maybe there were two episodes, but in the one I remember it wasn’t anthrax, it was typhus.
Fretful Porcupine, something like 90% of their episodes were poetic license. Speaking as someone who as a youngster practically memorized the books, and only recently was able to see a few episodes, I was moderately horrified. (There were other things to be horrified about, but you’d think they could have TRIED to stick to the books a little more than they did.)
I’d swear that one of the ones I saw involved anthrax, but damned if I know what happened in it.
They went off looking for Pappy Glen and his Elixir X. But it took two episodes because he operated out of a wagon.
Of course I was feverish when I first saw those episodes, so I could have hallucinated much of it. 
In the episode, these bad guys have these sheep dying of anthrax, so they sell the meat to the people of the town, people eat it, and everybody gets anthrax. A bunch of people die, including the people who sold the sheep, but Pa manages to bring back medicine that cures the anthrax.
Little House on the Prarie probably isn’t the best show to watch if you’re looking for historical or scientific accuracy. The books were good, though.