Case study sub edited by Phil Tucak.
Little the cat suffered major maxillofacial trauma which combined with a chronic rhinitis, resulted in the cat being referred for specialist dental intervention. A seven- year-old male castrated domestic short hair cat, Little presented to the dentistry and oral surgery service at Animalius Vet in Perth for extraction of fractured mandibular canine teeth. His injuries were a result of major maxillofacial trauma and the referring veterinarian was concerned about the potential instability of the mandibular symphysis and the risk of mandibular fracture on extraction of the affected teeth.
Little’s owner had advised that the cat seemed to eating okay and did not seem to have any oral pain originating from the oral cavity. However, the owner also mentioned that Little had had chronic sneezing and nasal discharge for the past few years, with episodes of sneezing often preceded by drinking.
As a kitten, Little was originally found by his owners with injuries to his head and face. At the time, he was evaluated at an emergency veterinary hospital and diagnosed with a palatine fracture, mandibular symphyseal separation and multiple fractured teeth. Treatment of his injuries involved circummandibular cerclage wiring and placement of an oesophagostomy tube. The tube and wire were successfully removed six weeks later.
Two years after the initial injury, Little had developed clinical signs of rhinitis, which was consistently refractory to treatment with corticosteroids and antibiotics. He was subsequently diagnosed with bilateral choanal stenosis on a CT scan, and treated with balloon valvuloplasty. Following this procedure, the clinical signs resolved for about a year, but eventually returned and ongoing intermittent sneezing and nasal discharge had been present for two years prior to presenting to Animalius Vet.
On presentation, Little’s clinical signs of rhinitis were being controlled with doxycycline (5mg/kg SID) and prednisolone (5mg/kg SID). On conscious oral examination, Little had multiple missing teeth, despite not having any history of prior dental extractions. He also had complicated crown fractures of the left and right mandibular canine teeth (304 and 404 respectively). Furthermore, a retained root fragment of the left maxillary second incisor (202) was visible. Significantly, although there was no nasal discharge from either nostril, and nasal airflow was present bilaterally, an approximately 1cm-long defect in the caudal hard palate could be seen, and a chronic midline oronasal fistula was confirmed by passing a periodontal probe into the nasal cavity through the defect.
The oral examination findings were discussed with the owner, and a CT scan of the head was recommended to determine the extent of the bony defect under the oronasal fistula, as well as to evaluate the nasal cavity. Full-mouth radiographs were also recommended to rule out retained root fragments from the multiple missing teeth.
The CT scan of Little’s head confirmed the presence of a narrow, midline defect in the palatine bone. There was also mild turbinate loss on the right side of the ventral nasal cavity. Full-mouth radiographs revealed the presence of multiple retained root fragments, periapical lucencies associated with both mandibular canine teeth, and multifocal tooth resorption.
The narrow nature of the defect and the amount of underlying palatine bone allowed for the use of the ‘von Langenbeck’ palatoplasty technique to close the defect. The oral cavity was rinsed with 0.12% chlorhexidine gluconate, and bilateral infraorbital and left and right inferior alveolar nerve blocks were performed with 0.3mls of 0.5% bupivacaine per site.
Bilateral lateral releasing incisions were made approximately 3mm from the dentition extending from the level of the maxillary 3rd premolars to the caudal end of the hard. The margins of the defect were tangentially excised with a size 15 scalpel blade. The palatine tissues were elevated bilaterally with a periosteal elevator to ensure tension-free flap apposition, taking care to identify and preserve the major palatine arteries. The defect margins were opposed with 5-0 poliglecaprone-25 suture material in a simple interrupted pattern.
Treatment of concurrent dental disorders was planned under the same anaesthetic episode. A total of 14 teeth or root fragments were surgically extracted via mugogingival flaps, including the fractured mandibular canine teeth. All extraction sites were sutured closed with 5-0 poliglecaprone-25 suture material in a simple interrupted pattern. Post-operative radiographs were performed to confirm complete extraction of all of these teeth.
Little recovered uneventfully from anaesthesia and was discharged with buprenorphine (0.02mg/kg transmucosally BID) for analgesia, and instructed to continue with administration of the doxycycline and prednisolone as previously dispensed. Feeding soft food, and refraining from any form of play involving the oral cavity for two weeks was also recommended.
One month following surgery, the owner reported that the prednisolone and doxycycline had been discontinued, while clinical signs of rhinitis had resolved. On oral examination, the oronasal fistula surgery site and the extraction sites had healed without complication. Examination of the site of the oronasal fistula with a periodontal probe confirmed complete resolution.
Acquired palatal defects may be caused by periodontitis or trauma. When acute, these defects result in oronasal communication, but the term fistula is reserved for chronic cases where the passage becomes lined with epithelium. In Little’s case, the oronasal fistula was most likely associated with insufficient healing of the original palatine fracture which occurred several years prior to presentation, allowing epithelium to migrate into the defect.
Acute acquired palatal defects with oronasal communication should always be carefully repaired to minimise the risk of oronasal fistula formation. Palatal defects allow liquids, food particles and other potential foreign materials a means of entry to the nasal cavity, resulting in chronic rhinitis. As seen in this case, narrow defects may not be clearly visible on CT, and imaging findings should always be interpreted in conjunction with detailed oral examination. Clinical signs of rhinitis will typically recur despite medical management until the defect is surgically closed.
Dr Kevin Ng BSc BVMS (Hons) MANZCVS (Small Animal Dentistry & Oral Surgery) Diplomate AVDC, Veterinary Dentistry Specialist
Dr Kevin Ng graduated from Murdoch University in 2006. After spending eight years in small animal general practice in the Perth area, he became interested in veterinary dentistry and successfully passed examinations conducted by the Australian and New Zealand College of Veterinary Scientists (ANZCVS) in 2012, becoming one of the few Members of the College in Small Animal Dentistry & Oral Surgery. He started Perth Pet Dentistry the same year and has been accepting referral dentistry cases since.
From 2015-2016, he directed the Dentistry & Oral Surgery Service at a large, multi-disciplinary hospital in the Perth area, undertaking a part-time residency program at the same time, before being offered a full-time residency position at Cornell University Hospital for Animals, one of the top veterinary teaching hospitals in the world.
After successfully completing the intensive residency program at Cornell in 2019, Dr Ng successfully sat board examinations for the American Veterinary Dental College. This qualifies him as an internationally-recognised specialist in veterinary dentistry, and one of only four registered specialists in this field currently practising in Australia.