I'm far from an expert in this, but I've had some experience, for sure.
Not long after we first got Max....I'm trying to think how old he was when we first took our 8-9 hour drive.....but suffice it to say, he was a puppy....I'd say he was around 9 mos old...he was perfectly fine with the trip..he slept between me and dh the whole way..it was amazing. Fast forward to a few months later....he started shaking and freaking out when we went ANYWHERE in the car...I thought it was b/c of my dh's penchant for complaining and bitching constantly when he's in the car....but it seems like Max just has gotten to that "age", where they are afraid of the noises and everything else associated with the car. He shakes on short trips to restaurants, the vets...no matter where....he starts shaking as soon as he gets into the car. He's fine once you get to where you're going...and he's fine on the way back..which is kind of odd.
But let me tell you...we just had to drive 9-10 hours for Christmas....what a nightmare. Max shook, panted, and whined from the time we got into the car til we got to where we were going. We stopped several times to let him out, and he was fine out of the car...once back in the car, the shaking and panting resumed.
When we got to our destination, I knew I couldnt' deal with a return trip of the same nature, so I checked here to see what other people who had similar problems did....some said that Rescue Remedy worked for them...I made a trip to the health food store (In another town) and spent $15 on it, took it back to the hotel (thank GOD I tested it on him before we had to drive home again) gave him 1 drop and within 10 min. he was hallucinating! That lasted at least 2 hours....with him chasing his behind, licking his nose, frantically looking up at the ceiling like something was coming to get him..that could only have made a 10 hour car trip everything you've ever wanted it to be
....anyhow, I finally went to Petco and talked to a girl who worked there and she suggested something that worked pretty darned well...a tablet called "Content-um"....I will try the Rescue Remedy behind his ears while we're at home and see how it does...I gave it to him orally (I'm an RN....c'mon..that's how we give a lot of stuff), and a friend swears by it (but she's got BIG dogs....I think it really makes a difference with these little guys...I had the same problem with him when he came home after his pancreatitis episode and they had him on Metaclopromide (reglan)...he was hallucinating..so we stopped it and he instantly got better).....every dog is different, just keep that first and foremost in your mind..what works for one, may or may not work for antother, which is why I tested the rescue remedy on Max before we had to take a long drive! Good luck, and if you find anything that helps, please post it and help us all with this problem!