Extremely aggressive 3 year old male GSD

Question
My mother has had an extremely aggressive 3 year old male GSD since he was a puppy.  The problem is he doesn't let anyone near her.  If anyone approaches the house he has to be locked in a room because he barks aggressively at the front door.  He never seems to want to bite any people, just will jump on them and bark at them as they enter the house.  The thing I am most concerned with is his aggression towards all other animals.  He viciously growls and attempts to snap his leash to get to any type of animal whether it be a bird or a horse.  I am asking these questions because I will be taking him from her in a few weeks since she is moving to a new property that doesn't allow his breed.  He will be living with me in my townhouse and I am a little worried about what the neighbors will think of him.  His behavior towards me and my girlfriend are extremely positive, however it is the protective nature he exhibits towards us and our property that has us worried about liability.  Is it too late to change his behavior or is there anything that we could possibly do?  Thanks in advance.

Answer
Is he neutered? Has he been to obedience classes? Is he power walked every single day for forty five minutes at heel? Beyond that, how much exercise does he get? How much protein is in the food he eats?
In addition to answering these questions. go to alpha dog boot camp on the web. Learn to establish and maintain pack order. It will changes his life and yours, for the better
Cindi