The Bach Flower Essences are the only one I had my vets at home or at OSU recommend. http://www.yearstoyourhealth.com/bach_flower_essences/faqs.html
I'm sure there is a lot of them out there; but that is the only one I have been told about that I can safely recommend. When I worked there some of the dogs or cats would have to take med's before coming in; but, that was usually due to very high aggression and not fear. I'm sure a lot of the homeopathic herbs or med's are fine. I've just always been a little leery of them personally unless it's cleared threw alot of different vets.
Ghilly once mentioned to me that RESCUE REMEDY (one of the Bach flower essences) might help. I don't know about using Valerian, or anything like that, I haven't the experience to know if it's harmful or not for dogs. A homoeopathic med: (Aconite, or Gelsemium, 6c 2 tabs.) might also help. Homoeopathic meds are completely harmless to dogs. They either work, and work quickly and efficiently, or they just don't work at all. They are a bit mysterious, but many is the time in the past when I have treated a dog with homoeopathy very well, for many little problems.
I'm searching around for something for my dog, as she is scared at the vet's and will probably try one of these for her next visit.
Maybe Bach Flower Essences your thinking of? I think they sell it at the GNC stores too.