Rat Terrier Breeder Wanted

We recently acquired an "abandoned" small breed dog, supposedly a chihuahua X. However, our research has indicated that she is most likely an American Rat Terrier from internet search for details of this breed. We live in the fish Hoek area of Cape Town. We are endevouring to not only trace the origin of this very beautiful little dog of approx 6 months old but also for more local information on the breed. Who can be contacted in our area to determine her breed and origin. Looking forward to some response in this matter. Regards, Nick