Rescue Dog

Question
Hi,

MY mum has recently got a resuce bitch, she is a staffordshire bull terrier mix. She looks like more staffy than any other breed. She got on really well with dogs in the kennel, and also my nephews who are 3 and 5, when they collected her. They took her home last night and she has gone for my mums Jack russell who is a male.. twice but it has been mainly over food. I have advised my mum that the dog was probably scavenging for food and most probably needs to be taught that she is an equal to the other dogs in the family. Have you got any ways to how we can train her to accept the other dog.. she is okay with the bitch.
She was a rescue dog, she was a stray and we think that someone had her to get a liter out of her then dumped her as she is quite skinny. I have given my mum a safety muzzle, and told her to keep that on her until my mum is not so nervous, and also told her not to be nervous as the dogs will pick up on it.
Thanks in advance

Answer
What does "mainly over food" mean?  The implication is that this aggression has occurred under other circumstances, as well.  A dog should NOT be wearing a muzzle in the house or for any extended period of time.  I'm uncertain what a "safety muzzle" is: if this is a velcro muzzle forcing the dog's mouth shut, it is not humane; any sort of muzzle is well perceived by the dog itself as restraint and any dog wearing a muzzle knows very well that when it is removed there is no longer such restraint.  VERY BAD IDEA.  One does NOT "promote" a dog in one's dog pack, "teach" a dog that it is equal to the "other dogs in the family", that is NOT how it's done.  You don't seem able to manage this situation alone.  Regardless of the reason the dog is aggressive, whether because she was starving in the streets or abused by some idiot, she's ALREADY demonstrating a problem.  In one minute she could kill that Jack Russell.

In Britain there are many state certified dog behavior experts.  I strongly suggest you find one:
http://asab.nottingham.ac.uk/accred/reg.php
http://www.apbc.org.uk/members.php

Meanwhile: keep the dog securely on house tab (leash with handle cut off), TAKE OFF THE MUZZLE, observe the dog closely, very closely.  If those young children are in the house, this dog is NOT a suitable companion for them.  Feed her separately (twice daily, no dog should be fed just once a day) from the other dogs in a secured area: put bowl down, walk out, close door, leave dog in there for fifteen minutes, open door, remove dog, pick up bowl out of her sight.  Institute a positive reinforcement training program RIGHT NOW and make this dog "work" for everything with a cue for "sit".  As time passes (two to three weeks), and she shows no food aggression toward humans (OR NO OTHER sort of aggression, none at all), make her "work" for one of her meals by handfeeding throughout a few hours.  Learn about this training at Dr. Ian Dunbar's video training course:
http://www.youtube.com/watch?v=Hv38ornzzuQ

If your mother is afraid of this dog, she doesn't belong in that home.  This situation absolutely requires in person evaluation.  Find an expert from one of the sites above.