Hey corgipaws. Since you have experience with pembroke welsh corgis, maybe you can help me out. When I used to work at a daycamp for dogs, a female corgi used to always come in. Lucy. She was about 1.5 years old and spayed. She was great! Very sweet with people and very playful with all dogs. But then I don't know what happened. The next day she came in, she attacked another dog. Boy, can corgis fight! She got so aggressive. I don't know the story behind this, as I ran in the room right when she attacked. I immediately pulled her off and took her out for the day. The next day, she did the same thing. Different dog this time. Neither dog was hurt. The thing that bothers me though is that she was completely fine one day, and the next she didn't play or let other dogs come near her!!! It's like it happened over night...Did you ever encounter something like this?