Surgical repair of a chronic, oronasal fistula in a horse using an alveolar bone flap

Abstract

Summary An 8‐year‐old Andalusian stallion was presented to the Equine Hospital with a 1.5 year history of an oronasal fistula measuring approximately 2 cm long (caudal to rostral) by 1.5 cm wide following an oral extraction of the right second maxillary premolar (106). An alveolar bone flap was created adjacent to the oronasal fistula and rotated axially and ventrally to close the oral aspect of the fistula. At 3 days after surgery, clinical signs of the fistula, such as green‐tinged purulent nasal discharge and malodorous breath, were no longer evident. At 10 days after surgery, the oral opening of the fistula filled with granulation tissue and mucosa and decreased in size to less than 2 ml. The horse was fed a pelleted mash and grass diet and the small fistula was flushed orally twice daily until it completely healed. At 6 months following surgery, the fistula had completely healed. Few options are available for repairing an oroantral or an oronasal fistula in horses. This case report suggests that a large, chronic oronasal fistula involving the alveolus of a maxillary second premolar can be repaired successfully with an alveolar bone flap.

Computed tomographic description of the highly variable imaging features of equine oromaxillary sinus and oronasal fistulae

“…Diagnosis of a fistula is most readily made following clinical presentation of a purulent, malodorous, unilateral nasal discharge, commonly accompanied with history of maxillary cheek tooth extraction . Diagnosis is confirmed through a combination of oral examination, oral and sinus videoendoscopy, radiography, and computed tomography (CT) …”

“…Patency with either the nasal cavities or a component of the paranasal sinuses is indicated if fluid drains from the nostrils following lavage . Food material visible within the sinus or nasal passages via endoscopy further suggests presence of a communication …”

“…Radiographic and CT examination of the skull can provide findings suggestive of fistula presence . Radiographic findings in such cases may include fluid lines within an affected paranasal sinus, and regions of soft tissue opacity, potentially combined with a mottled appearance consistent with a food‐filled sinus .…”

Equine oronasal fistula repair: Clinical commentary from a human surgery perspective

“…With anterior fistulae there is a reduction in the amount the oral mucosal layer can be undermined and adequate access to the nasal layer is challenging; an upper buccal sulcus incision significantly improves surgical access to the nasal side of the fistula. In a similar fashion, the location of the troublesome fistula in the reported equine case (Easley and Freeman 2016) encompassed the alveolar margin and hence required a more complex solution: the use of a hinged bone flap would be difficult to replicate in the situation in man due to the different anatomical size of the maxilla. The surgical exposure in such cases in man is carefully planned to maximise subsequent tooth development.…”

“…In summary, the authors' (Easley and Freeman ) report an interesting and novel method of oronasal fistula closure in an equine patient that has many underlying principles in common with the situation in human patients.…”