Cosette does the throwing-up-bile thing on occasion, and in her case, it always seems tied to overexcitement. We've been working with her to get her used to cohabitation with our cat, and she's puked up bile in at least two instances when we picked the cat up or the cat ran across the floor, and we had to calm the dog down and take her attention away from chasing. Just another data point for you that may be helpful!
