Dog owners, help. Xena has been to dog training classes. She has an inground fence. We exercise her; feed her, well; love on her; get her regular vet checkups; and brush her teeth. But nothing seems to be enough. When we got her from a shelter, she was in the company of 40 other dogs, all sizes. She acted mild and friendly and sociable. We walk her in the park daily, weather permitting. I play ball with her, once, twice, three times a day, sometimes. She's getting more and more aggressive toward other dogs. She fights and growls and attacks other dogs, no matter the size. Anybody have any suggestions. WB's mom's dog was here a couple weeks over the holidays. Xena let her cousin eat and drink from her own dishes but occasionally, seemingly for no reason, fought with that dog.