Please Help Me,Adopted dog always attack others

Question
I am a animal lover and had lived with my male Caribbean for 13 years.I had kept him in good shape and he is still youthful and healthy.My past colleague knew I took good care of dog and given us her 4 years old  spayed female Australian Terrier Happi ,as she do not want her anymore.When I rehouse her, I send her to a checkup at the vet and found she was not taken good care of and had skin disease and blood parasite.I nursed her back to good condition and provide her a good home with love.But  now after 4 weeks,I found she had behavior problem. She attached passerby and had bitten 2 person.One had asked me to pay for medical fee.She attacked many dog and even Benji.There are 3 incident happen, that when she saw a dog or neighbor passing by,she will get so heat up that  she will shouting and whining and must get into a fight but because I hold her tight and she will attack Benji since he was walking beside her.Benji get so frustrate but always forgive her.I wonder is Benji Stress out that he keeps biting his hind leg.I had bought her new bed but she still want to sleep on Benji's bed and drink from Benji's bowl.Happi always have a problem that she keep biting her front leg.In the past,she is living with his father and I wonder why she will have this agrgressive.Can I change her?Will she become a more peaceful dog and stop attacking people and dog?Thankyou your help is greatly appreciated.  

Answer
Hi Lim amy,

Although Happi may be a sweet pet, she has a aggressive and dominate nature. Attacking people and other animals is a serious issue,  Happi should be evaluated by a professional dog behaviorist, and also have the behaviorist work with you to train her.

Until Happi can be reconditioned and desensitized,  you need to take precautions. Happi, she should wear a muzzle when out in public. Never allow her outside without a leash.  
A basket style muzzle is the most humane, it allows a dog to pant, and even drink water while it's being worn. Here is an example of this style of muzzle:
http://www.morrco.com/dog-muzzle.html

When Happi suddenly attacks Benji when he's just walking beside her, it's called "Redirected Aggression".  It happens when Happi cannot take out her aggression on the actual object causing the fear, anger, or territorial thoughts,  so she attacks the dog nearest to her, which was Benji, but it can just as easily have been you or another person!  Benji does not in any way cause these attacks upon him, the fault is with Happi.
Because it's a difficult behavior to stop, it would be best if you worked with a  dog behaviorist to train Happi out of this.

If it comes to the point where Happi is just too much of a liability for you, or you simply can't make headway to stop her aggression, then it may be that Happi just isn't a good for your household. If that's the case, finding another home for Happi would be a good idea.

Best of luck,
Patti