If Angus is young he may grow out of this....lots of dogs do at about 1 yr. Being scrupulous about not feeding B4 trip, and going light on water, worked the best for my dogs. Also A/C if it's very hot where he is riding, or lots of air. I've never tried dram. for dogs, but a vet once did give me canine tranqs that turned an easy-going basset into a she-bitch from hell...they sometimes cause more trouble than they cure.

Good luck, Angus!