Adjunctive use of a collagen membrane for surgical closure of oronasal fistulae in dogs with challenging local conditions: a case series.

This case series describes the clinical outcomes of adjunctive use of a collagen membrane in the surgical closure of oronasal fistulae (ONF) in dogs presenting with clinical conditions that may compromise stable closure using a standard single-flap technique. Six dogs (eight maxillary canine teeth) with ONF were included in this consecutive clinical case series, selected based on the presence of multiple challenging clinical conditions, often in combination, including marked loss of buccal gingiva, insufficient alveolar bone support, and reduced soft tissue mobility associated with scarring. Following extraction of the affected teeth, a mucoperiosteal flap with adequate tension release was created. A trimmed collagen membrane was then placed on the nasal surface of the mucoperiosteal flap to support the suture line, and primary closure was achieved using a single-flap technique. In all cases, clinical signs associated with ONF, including epistaxis, nasal discharge, and sneezing, resolved within 14-21 days postoperatively. During the available follow-up period, no clinical or oral findings suggestive of fistula recurrence were observed. Although this technique is not intended to replace established closure methods, the adjunctive placement of a collagen membrane on the nasal surface of the mucoperiosteal flap to support the suture line may serve as a temporary supportive measure to stabilize the early healing environment at the suture line during the immediate postoperative period. The collagen membrane does not reduce the need for appropriate flap design or adequate tension release in selected ONF cases with challenging local conditions.