I have adopted from the dog pound a 3-4 yo male terrier mix. He loves me to death. However, he has gone after four of my female friends, growling, showing his teeth and snapping at them. I am a female also. He has drawn blood. This has not happened to all females entering my home. I am afraid he could have done some serious harm had I not got hold of him in time. Help. He is otherwise a great, loveable dog, house-trained and all.