My chihuahua has serious panic attacks when it rains!? help?

It is probably more to do with the fact that she doesn't like the sound of the rain, or it reminds her of being in the rain on the street. It's pretty easy to solve, you just need to get her used to the sound and she should be a lot better when it rains. Buy or burn a CD of the sound of rain (while your at it throw in some thunder too). When its nice outside, play the CD quietly in a room with your dog. Stay in the room with her and pet her and calm her down (remember to play it very quietly). Sometimes you can just leave it on in the house. Do this often, and after a while start to turn it up slowly. Keep doing this until it is the regular noise level of rain. She should be fine after that. If she is not, keep trying, but it may be more of a mental issue.