What happened to Dr. Ledoux on Little House on the Prairie?

During the episode Dark Sage, in season eight, Doc Baker brings another doctor into town to help with his practice.  However, Dr. Caleb Ledoux is African American, something Doc Baker didn’t realize, and Dr. Ledoux begins to suspect prejudice in Walnut Grove is impacting the patients he is receiving.  For example, his first patient is a horse, and his second is merely treating Cassandra’s scratched arm.

Later, when Doc Baker is unavailable, Dr. Ledoux needs to help Mrs. Sherman deliver her baby, but her husband prevents the doctor from treating her, until Charles Ingalls interferes by punching Mr. Sherman.  Dr. Ledoux successfully delivers the baby.

When Doc Baker returns, he apologizes for the racist behavior Dr. Ledoux has received and asks him to stay in Walnut Grove to help with his practice, which he agrees to.  But then, we never see Dr. Ledoux again.

The actor who portrayed Dr. Ledoux, Don Marshall, was only engaged for a single episode of the show.  And while he doesn’t appear on the show again, the character is not mentioned again on the show either.  So it appears that Dr. Ledoux is still in Walnut Grove until the show ended with Walnut Grove being blown up, but we do not know anything else about his time there.