I have 2 Maltese-x which i have had in my care for the last 3 years, they are 4 and 4 and a half. The oldest was recently sick, so received extra attention (emergency trips to the vet, antibiotics, etc). Since then, the younger, who is the more dominant, has become extremely jealous towards the other. Every time i pick up or pet the other dog, she growls aggressively, then attacks her, often going for the throat and tearing hair. She sometimes acts the same way when i feed them, even though the are fed the same food at the same time. This is strange as she never acted like this in the last 3 years. It doesn't matter how much attention i give her, she still acts this way every time i give any attention to the other dog? I know it's not the right thing to do, but the only way i can calm her down is to punish her by smacking her on the nose and putting her outside (which probably only fuels her jealously/dominance issue). Help!