There is a product called Kids Rescue Remedy by Bach. It is an all natural product, no drugs or chemicals or alcohol in it. It is made for children for natural stress relief but my vet recommended it for our dog, who is a chilhuhua mix and you know how nervous they can get. We were traveling to WA in our car, a 3 day trip, she's elderly, and I couldn't give her any medication because at her age it could kill her.
Wow, does it work great! A few drops and by 20 minutes into the trip she was calm and relaxed, not doped up, she got out of the car at every rest stop (and we stop a lot being a little long in the tooth ourselves)and I only had to use it twice, she travels great now!
I got it at a health food grocery store, I told the gal that was helping me I was buying it for my dog, she said everyone buys it for their animals because there nothing in it that can harm them. So, you might give it a try.