2 Female Shih-tzus Fights

Question
 I have 2 female shih-tzus one of which is 18 months and blind,Penny, while the other is nearly three,Roxie. They get along very well most times and play with one another.
 we have had both since they are 8 weeks old. However sometimes for no apparent reason a fight will break out, mostly initiated by Penny. We take every precaution once they fight to separate the two for the remainder of the day.
 However it is impossible to determine which actions or situations trigger these fights and more often than not they play fight more than anything. We love these two dogs dearly and would do anything and everything to stop the fighting and restore the peace that once existed between the two girls. Any information to do so would be very greatly appreciated!

-Ali

Answer
It sounds as though your young dog may be challenging the older one for status in the pack now that she is at the age of social maturity.  Or, it could be that, because she is blind, she has trouble reading the signals of the other dog.  At any rate, because they seemed to get along before, I think it may be the first scenario.  If they like one another, and this is occasional, plus no blood is drawn, you may be able to see them resolve it.  However, occasionally, it does happen that two females, once both are adults (especially if they are close in age or status) decide to dislike one another.  In that case, you need the help of a behaviorist to determine if they can safely live together.  You can find one at the Animal Behavior Society web site, or at IAABC.