With the heat are critters coming out of hibernation. One of the other risks to your pet is the poisonous snakes. Rushing to an emergency clinic would not be fun at anytime so prevention is the best policy. When out in areas where it is known there are snakes, keep your pet on the lead. Circumvent any snakes on the path or backtrack the way you came to avoid them.
Many dogs have a phobia surrounding thunder.
You need to consider obtaining professional help with this phobic behavior from an animal behavior consultant. Unfortunately, many owners try and comfort the dog and end up complicating matters. Your participation and preplanning is required to work through this. In the meantime, make sure you have a secure area for your pet and an ID tag on the animal at all times. Keep your animals out of the yard while spraying and use caution for several days later.