Fear of thunder is a common phobia in dogs. It is usually marked by hiding, whining, barking, pawing or even urination. No one is exactly sure what makes dogs afraid of thunder. It does seem to be more common in some breeds than others.
Anxiety about thunder is difficult to treat but it is important to try because the anxiety usually gets progressively more pronounced with age.
A dog who suffers from a fear of thunderstorms may begin to display anxious behavior long before the thunder begins. Rain on the roof of the house, bright flashes of light or even the drop in air pressure before a storm may be enough to trigger an anxious response. A fear of fireworks is also common in dogs that are afraid of thunder.
Don't punish or cuddle
When dealing with this phobia it is important not to punish your dog for being anxious nor cuddle him too much as this can exacerbate the problem. Punishing the dog will only make him more afraid and anxious, since he will associate thunder not just with fear but punishment as well.
Cuddling or comforting your dog too much is also inadvisable because it teaches your dog that his anxious behavior is appropriate and pleasing to you.