What do you think happened to Bolt's mom?

I Think she died

I think that she had tuta and then they sent the tuta out to different places, or the tuta in the same pet store could be bolt's bro's and sis's but just doesn't look like him. It is srtange that all of the tuta look the same exepet for bolt, is it sapost to be the same breed? Bolt just could be white I guess but I think that only American shepards are white, mabey they are brown, I don't know, in the book and in the movie, they never told. None of the bolt facts tell either, so ask disney.