Does she vomit food or does she vomit a foamy, clear
liquid? Some
dogs overproduce bile and stomach acid and
when too much time elapses between meals or a meal and a snack they will throw up a clear yellowish foamy liquid. This is quite common and it's easily dealt with by feeding your dog a couple of smaller meals a day rather than one large one, and then a couple of cookies as late at night as you can manage them, preferably after midnight.