Sneezing and/or nasal discharge may occur with many diseases or conditions and are symptoms of upper airway disease (nasal cavity, paranasal sinuses). Nasal discharge may not be obvious, due to the tendency of dogs to lick secretions from their noses. Discharge is more noticeable as the volume increases, character of discharge changes, other physical abnormalities occur or secretions accumulate on the nostril, over surrounding hair or nasopharynx (causing retching or reversed sneezing).
Nasal discharge comes from several sources, including mucous cells and glands in the nose. Secretions usually move caudally (away from the nostril) by the mucociliary apparatus (small hair-like projections) and when they reach the nasopharynx (where the nasal cavity meets the throat) they are swallowed. When secretions accumulate to the exterior, it suggests that there is an increased production of secretions or an obstruction to drainage.
Veterinarians know that certain types of discharges are more likely with certain diseases, but there is overlap. Nasal discharge is not specific for any one problem but can actually be related to a number of different diseases or disorders.
Unfortunately, in older dogs, nasal neoplasia (cancer) is a very common cause of recurrent and progressive (becomes more severe with time) nasal discharge. Predisposed breeds include: Airedale terrier, basset hound, collie, German shepherd
, German short-haired pointer, keeshond, Old English sheepdog and Scottish terrier.