It may be either of those or a myriad of other things that may cause sneezing in dogs. An occasional sneeze or two in an otherwise happy, healthy dog is nothing to worry about, but frequent or repeated sneezing in a dog that seems unhealthy should warrant a visit to the veterinarian.
Dogs can sneeze due to irritants or foreign bodies inhaled into their noses. They will often sniff around and this is the body’s way to naturally expel them. They may also sneeze due to inhaled allergens such as grass and pollen.
Dogs can also have nasal mites that can cause sneezing and sometimes nasal discharge. They are transmitted from nose-to-nose contact with dogs. Fortunately, they are not very common and are easily treated once they are found.
Viral, bacterial and fungal infections can cause sneezing as well.
Other things that can cause sneezing include teeth problems or nasal tumors. Sneezing can be a calming signal for dogs just like lip licking and yawning. Finally, sneezing can be due to excitement, bug bites or rolling around on the floor. If your dog is sneezing frequently, has bouts of sneezing or is acting ill, see your veterinarian.