Causes of dogs panting rapidly:

1. If the dog has experienced strenuous exercise, it will pant very quickly.

2. Dogs will pant rapidly if they are in a stressful environment.

3. If the dog has cardiovascular disease, it will also cause the dog to breathe more quickly.

4. If the dog is infected with parasites, it will also affect the lungs and cause shortness of breath and panting.

5. If the dog is sleeping and panting rapidly, it may be caused by dreaming.