one of my mother's ancona's has developed a leg twitch. it has always been a bit cross-legged. Now it has a twitch where it is constantly lifting and dropping one of it's legs. Even if it stands on the twitching foot with the other, it still tries to raise it, so i think it's involuntary. Any ideas? It is about 6-7 months old and has just developed the twitch in the past two weeks.