my dog was like that .. it got so bad he almost passed out from fear.. what I did which is really exausting if you have to work the next day but whenever your next thunder storm is get up .. put lots of warm cloths on .. and get lots of treats really really good ones.. and take your dog for a walk be all happy and excited treating him every few seconds... first start in the house playing and treating then take it out side for a few min..

this worked for me the third time around my dog was perfictly fine other than the fact he wanted to play instead of sleep when a thunderstorm hit.. but hey thats better than being afraid.. and soon you can calm the play down too and say no sleep time.. hehe