If you can get your hands on it, somehow, get a copy of one of the concerts from the In The Flesh tour of 1978. I can't even begin to explain how awesome the music is; Dogs played live.
I used to be part of several online bootleg trading rings for Led Zeppelin concerts in the 90s (back when trading was done on Maxell Type II metal tapes and Kodak gold CD-Rs were just coming on the scene -- the purist collectors argued vehemently against MP3 trading -- and rightfully so).
Led Zeppelin were one of the most bootlegged bands of all time, followed closely by Pink Floyd. I have amassed a fair quantity of Led Zeppelin concerts and was thinking of joining the Pink Floyd trading circles but decided against it as it was driving me broke, being a poor university student and all. Nowadays, you can torrent the entire lot in one hit.
Anyway, once again, Animals is where it's at. The double-tracked guitar solo in Dogs and Sheep's outro, are well worth the price of admission alone.