For the vast majority of breathing difficulties, the best thing a pet owner can do is to get their dog in to see their veterinarian to determine the underlying cause of the issue. However, there are some basic things you can do at home to help your pet.
For example, a calm, cool environment is helpful for most pets with breathing issues.
If your dog is having a reverse sneezing episode, some owners find it helpful to gently stroke their dogs nose or throat.
If your pet has previously been diagnosed with allergic airway disease or bronchitis, then you may already have a prescription for an antihistamine or a puffer that you can use.
It is always a good idea to avoid airway irritants if you share your home with pets. This means keeping them away from second hand smoke as well as things like incense and essential oil diffusers, especially if they have a known history of airway disease.