British Small Animal Veterinary Association position statement
ACP has, in the past, been used as a short-term tranquilliser during phobic events. However, it does not have anxiolytic properties and will therefore not alter the impact of an event unless the animal is rendered unconscious thoughout it. It is believed that immobilising an animal whilst leaving it aware of, and emotionally responsive, to a phobic event may intensify the experience and lead to worsening of phobia in the future. Oral dosing produces unreliable effects, and onset of action may vary between 15 and 60 minutes (BSAVA Formulary). High doses may be required in order to sedate a dog during a phobic event. High doses may lead to hypovolaemia, hyperexcitability and extrapyramidal side effects in some animals (BSAVA Formulary). For these reasons ACP is not considered suitable for the management of canine noise phobias.
and a re-post of some info I added to a thread in case it helps
What I've found really helpful for him has been
working through the relaxation protocol (can email you a copy)
teaching a 'relax' cue
TTouch and massage sessions (from me)
Valerian tincture (to begin with we used this twice daily in his food for about 6 months then weaned him off)
Valium given in small doses to block memory formation when something really scary happens like a huge set of fireworks or a thunderstorm
What didn't help us
DAP of any kind
CSJ calm down herbs
other 'generic' anti-anxiety stuff
t-shirts or wraps
I think its worth emphasising that for Finn his nervousness/anxiety/stress was very strong and involved physiological reactions like constant pacing, panting, staring, drooling etc. The specialist we spoke to felt that the stuff that had not worked for us was simply not strong enough to get through to his system.
Personally if your dog is really scared I would only walk her when its daylight and early enough there won't be any fireworks. Walk her on a harness AND flat collar (martingale type prevents escape without tightening too much). It really depends on the strength of the reaction, but until this year there would have been no point keeping Finn in the scary location as he would not have come out of the panic state. This year though that has been possible and we can now stay out and play ball - its taken 5 years to get this far though!
Since things have started going off its really much to late to start desensitising - I'd download the mp3 file and save it for after the fireworks.