Sasha is the name of one of Interplay's old producers, Vince Denardo. He did not work on Fallout 1 or 2. It was a bit of tradition to have his dog somewhere in an Interplay game, in some shape or form. Sasha is normally placed in the special thanks section or some other place in most of our older manuals."
Speaking of Vince, we liked him so much we placed his dog Sasha in the game. We tried to put her somewhere players could see but not get to, because we were afraid they'd try to kill it. We picked the Military Base... which gets nuked. Oops!