The Case of the Dog with Holes in His Head Sandra L. Waugh VMD, MS - Windsor Pet Dental
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ell, not exactly holes in the head, but holes inside the mouth that connect the mouth to the inside of the nose (nasal cavity). Such a hole is called an “Oronasal Fistula”, ONF for short. (Oro refers to the mouth, nasal to the nasal cavity, and a fistula is an abnormal passage.) In the dog, the upper canine, or fang, tooth has a very long and broad root, which slants inward from the side of the mouth towards the nasal passage. There is a thin shelf of bone that separates the end of the root from the inside of the nose (nasal cavity). This thin bone can be weakened or even destroyed by periodontal disease, creating a hole connecting the tooth socket to the nasal cavity. When the canine tooth is removed, either by extraction or by falling out on its own, the hole is then exposed to the inside of the mouth. If the gum is not carefully sutured closed, a permanent hole can be created. Why permanent? The body wants to heal tissues together. Ideally, the tissue lining the nose would heal together to close the hole on the nasal side, while the tissue lining the mouth would heal together to close the hole on the mouth side of the bone. With a large enough hole, there is no scaffold for the cells to stick to in order to seal the hole. Instead, the tissue on the mouth side heals to the tissue on the nasal side all around the hole, making the hole permanent unless it is repaired surgically.
Upper right side of dog’s mouth. The ONF is located approximately where the end of the root of the upper canine had been originally.
Upper left side of the same dog’s mouth. The ONF is located approximately where the end of the root of the upper canine had been originally. 52 4 Legs & a Tail
A hole in this position will cause the dog a great deal of distress and pain. Image if food or water went into your nose ever y time you ate or drank. These poor dogs suffer with chronic infections of the nasal passage, constant nasal discharge and the danger of inhaling food particles, which can cause pneumonia. Typically these dogs sneeze after eating or drinking, and rub their faces excessively on the f loor or paw excessively at their nose. I imagine that they must have headaches all the time. These holes can occur on one side only or on both as in this Dachshund, a breed that is known for having ONF’s. Dog breeds with noses that are long in relation to their skulls are at risk for ONF’s. There are a variety of surgical procedures described for closing these holes. They can be difficult to repair, and may take several attempts to fully close. The repair requires that the two sides, mouth and nasal cavity, be separated by incising the two tissues apart. With a large hole, providing some
Oronasal Fistula Symptoms of an oronasal fistula can include a chronically runny nose, with or without bleeding, and persistent sneezing. It can occur in both cats and smaller dogs, ten pounds or smaller. Causes of ONF include: • Trauma • Bite wounds • Oral cancer • Electrical shock • Periodontal disease • Traumatic tooth extraction • Mandibular canines (the fang-like teeth) positioned toward the tongue • Upper jaw overbites, which causes the canine teeth in the bottom jaw to pierce the hard palate (roof of the mouth) Spring 2022
