[Gandalf] has led us in here against our fears, but he will lead
   us out again, at whatever cost to himself. He is surer of finding
   the way home in a blind night than the cats of Queen Berúthiel."

When I first read the story I had no idea who this queen or her
cats were. Well it turns out that she was a Black Numenorian
and the cats were her spies.

They remind me of the Watchbirds, those avian snitches who spy
on little kids and than tell on them to their mothers.

These nasty little tattle-tales appeared for years in
the _Ladies' Home Journal_:

http://en.wikipedia.org/wiki/File:Watchbird1.jpg