I believe your little girl is showing classic
fear aggression because of being hit and by the children in the home. This is very serious and I don't want to see your son hurt but I think you need to bring in an expert as you do not have the knowledge base to help your little girl. You are very lucky as the University as a department to help you or could direct you to someone even closer to your home. I feel very strongly that you just can't open the yellow pages and get a trainer as anyone can train dogs and they can do even more damage with your little girl. I believe you need a Board-Certified Veterinary Behaviorist which the University has.
Please do not try the dominant theory with her or you will do even more damage to her. She is scared out of her mind and she attacks because of this. Sorry but not all Yorkies like children and also she is now on her second home so you will need patience to alleviate her fears.
I think you can turn her around but it will take patience and postive training.
Animal Behavior Services - CVM - Veterinary Medical Clinic, University of Minnesota
Solid Solutions
With many dogs you can develop a great foundation for avoiding and working through behavior issues through training class and practice, daily grooming, diligent veterinary attention, and good management structure in the home. It takes time, knowledge, skill and effort to learn and to do these things, though, and some dogs are just “problem children,” no matter what you do! The experts stay busy helping us with our dogs for good reasons!
Your regular veterinarian is the best resource to keep your dog’s health care in great shape and to help you figure out where to find the other expertise you need for your dog. A veterinary behavior specialist may be further away, but well worth the travel for an aggression problem, a dog who is obviously suffering from anxiety, or any other situation that makes an expert assessment of the dog’s temperament important. If you need a veterinary behavior specialist, ask your regular veterinarian to help you find the closest one. Follow-up to the work with the specialist will most likely include your regular veterinarian. Specialists are routine in veterinary medicine now, but regular veterinarians can be indispensable!
Don’t put off the veterinary behavior specialist until “the last resort.” A behavior becomes more set and more difficult to change when it continues for a longer time. With a young dog, you also want to use developmental periods to maximize behavior improvement much more than is possible if you wait until these critical periods are past. They pass quickly.
Whenever possible, take aggression and serious anxiety problems to the veterinary behavior specialist quickly, so the right assessment can be made and treatment begun in good time. It could very well save your dog’s life, or in some cases the life of a human. You will gain the knowledge to make good decisions about your dog’s care, and your family will benefit, too.