This is usually an advanced form of periodontal disease. It occurs when the bacteria in plaque destroy the periodontal attachment and bone of an upper tooth until it reaches the nasal cavity. This is most common in small breed dogs (Daschunds, Yorkshire Terriers, Maltese, Poodles). It is usually due to loss on the palatal (or inside of the mouth) aspect of the canine teeth. The reason for this is the root of the tooth runs up alongside the nasal cavity, and is separated from it by only a thin sheet of bone. The periodontal disease will destroy this structure along with the normal attachment for the tooth. This results in a communication between the oral cavity and the nose. The bacteria in the mouth will cause an infection in the nasal cavity. Clinical signs are chronic nasal discharge (blood or pus), sneezing, and occasionally anorexia and bad breath. These symptoms are often partially responsive to antibiotics, but will invariably recur when they are discontinued. This syndrome can also be caused by nasal trauma, cancer, or occasionally during extraction of a tooth. It can also occur secondary to other teeth, most notably the incisors.

The goal of treatment is to clean out the debris that has been packed into the defect and close the communication between the oral and nasal cavities. This is accomplished by extracting the offending tooth (if still present), and harvesting a flap of gingival tissue to cover the defect. This is done by creating a flap of gingival tissue on the buccal (or outside of the tooth) surface, and rotating it over the defect and suturing it in place. If there is a very large defect, or the single flap technique fails, a more involved double flap procedure can be performed. This is accomplished by first harvesting a flap of tissue from the palate and rotating it over the defect and suturing in place. Then make a larger flap on the cheek side to cover the defect and the area that the palatal flap was harvested from. This flap is also sutured in place. This is more difficult and invasive, but gives a much stronger repair.