An oronasal fistula is an abnormal open path from the oral cavity into the nasal sinus. In most cases it is not visible as a hole in the roof of the mouth; the fistula usually is along the root of a tooth.
The most common teeth affected is the upper canine tooth (the large front corner teeth). the second most common teeth affected are the large upper fourth premolars. The problem can occur adjacent to any tooth in the upper jaw. Oronasal fistula can also occur in the center of the hard palate.
Any dog breed can be affected, but dachsunds are by far the most common breed in which we encounter oronasal fistula. They are also more common in toy breeds, and they are rare in cats.
If there is a foreign object or oral tumor present we will remove it. This procedure ranges from simple to very complicated. Some oral tumors are inoperable.
Once the tooth, foreign object, or tumor is removed we create a flap of healthy mucosa (the soft tissue lining the oral cavity) adjacent to the fistula. We slide the flap over the fistula and suture it in place.
Failure of a properly placed flap is due to the constant tension on the margins of the flap caused by the pet breathing in and out through its nose.
In some cases we will surgically replace the failed flap, and in some cases we will allow the fistula to heal by second intention (contracting closed and filling in with healthy scar tissue). Healing by second intention can take weeks to months, but it is not a painful process and does not affect the pet's quality of life. Some oronasal fistulas ultimately do not close completely, but a persistently open fistula also is not painful and does not negatively affect the pet's oral or overall health.
In other words, the significant problem is not the fistula itself, but the problem that caused the fistula. Our primary goal is to treat the problem that caused the fistula. The prognosis for the pet's oral and over-all health thus depends on our ability to treat this problem: