Uma is becoming aggressive towards larger dogs. She lunges at them snarlsing, growling, and barking. Very hard to control on the leash when she sees one, otherwise she is good on the leash. She has no problem with smaller dogs,and makes many friends. I am hoping this is just a phase? Uma is 8 mo. old. Thank goodness I use a harness, otherwise she would hurt herself on a collar with all the lunging she does on these encounters. Any suggestions?