Nala was a rescue dog, Infact she wasn't a rescue dog she had to be stolen for her own well being.

During the Beast from the East, Nala was left in a garden and she had dug a hole in the snow to try keep her warm

So Jo decided this isn't on and took her out of the garden and homed her.. The previous owners, who we believed were using her to their means as a puppy farm, walked past Nala and Jo the next day and never asked for their dog back as they had then had their use out of Nala.

Nala can't trust other dogs, can you blame her? She is brilliant with humans but not other dogs.

So, just because if her breed don't judge her.