In the episode For the Love of Blanche, we meet a ex-circus orangutan, which is given to Mr. Edwards after he promises to take care of Blanche.
The episode is comical, and when Blanche attacks Nancy at school (where Nancy calls it a gorilla), Harriet Oleson insists that the orangutan be put to sleep as she deems it to dangerous to live. At the end of the episode, Mr. Edwards manages to find a zoo that is willing to take Blanche, so Blanche lives on.
After this episode, Blanche is never mentioned again, although it was an episode from the ninth season. But presumably in the show’s Little House world, Blanche continues to live her life in the Minnesota zoo.