My friend's Shiba Inu, Keiko (a 5 yr old male), has panic attacks on road trips. He shakes and pants continually. She has given him tranquilizers prescribed by her vet, even doubling the dosage, but he still pants and won't lie down to rest even tho he's asleep on his feet. And he's dopey and lethargic for a day or more after they arrive at their destination. He does not behave that way on short trips around town, just on road trips.
Has anyone had similar problems? Is there some natural herbal approach to calming the animal that doesn't have harmful side effects?