My 2nd suggestion would be natural tablets which relax them. Or, prescription, but the natural, if you find a good one, work well. I so wish that I had the bottle from the tablets that you sent me in 2003, when we moved the house, and the dogs were really freaked out. They worked better than any I've ever used. Darn. But, it just goes to show that some work well...those worked for either 3 or 4 different dogs.
My only other thought, are pheromone products. I didn't have especially good luck with them for dogs, but believe that Hattiemae has, for thunderstorms.
Probably the next time is 4th of July? That will give you time to plan, and if you try a Thunder Shirt, time for her to grow more before buying it.
Love All Life, Thank You For Posting! :)