Any suggestions about preventing my 8 mo. old chihuawa mix, Shadow, from throwing up in the car? She travels with my other dog, Cowgirl, in the front seat. Shadow hasn't learned how to stick her head out the window yet. Maybe when she does she won't get sick. She foams at the mouth right before she gets sick. I want to take them to the dog park, but I don't want her to feel sick. What should I do?