A 310-kg (682-lb) 9-year-old Welsh Mountain Pony gelding was evaluated because it was suspected that a persistent oronasal fistula had developed after a fractured right maxillary second premolar tooth had been extracted by repulsion1 via the dorsorostral aspect of the maxilla 6 months earlier. The repulsion procedure, carried out at the same hospital on an outpatient basis with the pony standing, had been performed because attempts to extract the fractured tooth via the oral cavity had been unsuccessful owing to severe decay of the tooth crown. Five days after the tooth had been extracted, a communication between the oral and nasal cavities was noted on endoscopic examination and filled with a temporary alveolar plug of polyvinyl siloxane puttya (Figure 1) Afterward, repeated loosening of the plug had resulted in persistent communication between the oral and nasal cavities and the need for repeated replacement of the plug.
On clinical examination, unilateral (right-sided), mucopurulent, green-tinged nasal discharge and malodorous breath were noted, but the pony otherwise appeared healthy and in good condition. Examination of the oral cavity confirmed that the right maxillary second premolar tooth was absent, and a 1-cm-long (caudal to rostral) by 0.5-cm-wide (medial to lateral) defect was evident at the oral aspect of the alveolus, from which feed material was extracted. Endoscopic examination showed feed material and mucopurulent discharge in the rostral aspect of the right nasal cavity. Approximately 10 cm caudal to the right external naris, a defect was noted in the middle nasal meatus from which feed material was exuding (Figure 2) The alveolar cavity was lavaged orally with physiologic saline (0.9% NaCl) solution to remove all foreign matter. Radiography revealed no osseous or dental tissue within the alveolus associated with the fistula. The diagnosis of a persistent oronasal fistula was confirmed on the basis of clinical examination and diagnostic imaging findings, and surgical repair was recommended.
The pony was admitted to the hospital, and initial surgical repair of the oronasal fistula was completed over a 2-day period. On the first day, with the pony sedated and standing, the tissue lining the alveolar defect was debrided by curettage and the alveolar cavity was lavaged extensively with physiologic saline solution. A shallow alveolar plug of polyvinyl siloxane puttya was then used to fill the coronal aspect of the fistula, and food was withheld until surgery the next morning.
The next day, 2 surgical procedures were performed in series to repair the oronasal fistula. For the first procedure, an alveolar bone flap was created by use of the technique described by Easley and Freeman,2 except that the procedure was performed with the pony sedated and standing rather than anesthetized. Phenylbutazoneb (2.2 mg/kg [1 mg/lb], IV), procaine penicillinc (20 mg/kg [9 mg/lb], IM), and gentamicin sulfated (6.6 mg/kg [3 mg/lb], IV) were administered before surgery. A 14-gauge IV cathetere was placed, and sedation was achieved by administration of detomidine hydrochloridef (0.01 mg/kg [0.0045 mg/lb], IV) and butorphanol tartateg (0.01 mg/kg, IV), with additional doses administered as required. The pony was placed in stocks and fitted with earplugs. An equine mouth wedge speculumh was inserted to hold the mouth open during the procedure, and the temporary alveolar plug was removed. The face and neck area on the right side were clipped of hair and aseptically prepared. The surgical site was locally anesthetized by injection of 8 mL of 2% mepivacaine hydrochloridei within the infraorbital foramen,1,3 and 5 mL of mepivacaine was infiltrated SC at the planned incision site. In brief, a skin incision was made, and then the buccinator muscle was dissected from the right maxilla. Three osteotomies of the maxilla were performed dorsally, rostrally, and caudally; the ventral aspect of the alveolar bone flap was left intact where it was fractured manually so that it could be deflected axially and trimmed carefully to fit tightly against the medial wall of the alveolus (Figure 3)
At the end of the first procedure, anesthesia was induced with ketamine hydrochloride,j and the pony was positioned in left lateral recumbency for the second procedure. A sliding mucoperiosteal hard palate flap was created as described by Barakzai and Dixon4 (Figure 4) In brief, a mouth wedge speculum was inserted, the skin around the right commissure of the lips was clipped of hair and aseptically prepared, and the rostral portion of the oral cavity was irrigated with dilute povidone iodine solution. Starting at the commissure of the lips, a 5-cm-long full-thickness (skin to buccal mucosa) buccotomy was performed to allow better access to the surgical site. The oral aspect of the fistula was debrided, and then a mucoperiosteal hard palate flap was fashioned by making a 1.5-cm incision (caudal to rostral) down to the bone on the medial edge of the fistula along the palatal aspect of the alveolar defect. The hard palate mucoperiosteum was elevated, and two 3-cm transverse incisions at the rostral and caudal edges of the fistula permitted the creation of the flap. Once created, the flap was advanced laterally and sutured to the gingiva. The greater palatine artery was accidentally transected during the procedure, which required that transfixing ligatures be placed on the arterial ends rostral and caudal to the edges of the flap. The pony's recovery from anesthesia was unremarkable; procaine penicillin (20 mg/kg, IM, q 12 h) and phenylbutazonek (2.2 mg/kg, PO, q 12 h) were administered for 5 days after surgery. Food was withheld for 24 hours after surgery, and then a semiliquid mash of soaked alfalfa cubes was fed 6 times/d for 4 weeks to minimize pressure on the healing tissues. The pony was discharged from the hospital 7 days after surgery.
One month after surgery to repair the oronasal fistula, the pony was returned to the hospital for a follow-up evaluation. Findings on clinical examination suggested that the oronasal fistula had healed, and endoscopic examination of the nasal cavity revealed no feed material or discharge. Following this examination, the owner was instructed to return the pony to its regular diet.
Five months after surgery, the owner returned to the hospital with the pony, reporting reoccurrence of the original clinical signs. Clinical and endoscopic examination confirmed that the oronasal fistula had reoccurred. Compared with its original size, the fistula appeared mildly reduced in size, but on the basis of the medical history and fistula location, surgical reconstruction was recommended. The pony was readmitted to the hospital at this time, and a plan was made to repair the fistula by use of an autogenous fascia lata graft.
Prior to the procedure, the pony received phenylbutazone (2.2 mg/kg, IV); xylazine hydrochloridel (0.8 mg/kg [0.35 mg/lb], IV) and diazepam hydrochloridem (0.2 mg/kg [0.1 mg/lb], IV) as premedicants. Anesthesia was induced with ketamine hydrochloride and maintained with isofluranen in oxygen. The pony was positioned in left lateral recumbency.
The skin over the lateral aspect of the right thigh and right maxillary region was clipped of hair and aseptically prepared. The rostral portion of the oral cavity was irrigated with dilute iodine solution. A 6-cm-long proximodistal incision was made through the skin in the craniolateral aspect of the middle portion of the thigh. The subcutaneous tissues were dissected bluntly away to reveal the fascial sheath. An elliptical 2 × 2.5-cm section of fascia lata was excised and wrapped in a blood-soaked gauze pad. The fascial defect was left open, and the incision was closed in 2 layers; subcutaneous tissues were closed with 2-0 polyglactin 910o in a simple continuous pattern, and the skin was closed with size-0 polydioxanonep in a simple interrupted pattern.
At the same time that the fascia lata graft was being harvested, a second surgeon made a 6-cm-long linear rostrocaudal skin incision over the alveolus of the right maxillary second premolar tooth. Blunt dissection through the buccinator muscle toward the oral cavity was performed, with special attention taken to avoid damaging the dorsal buccal branches of the facial and infraorbital nerves, parotid salivary duct, buccal salivary glands, and mandibular labial artery (Figure 5) Following buccotomy, thorough debridement of the oral aspect of the fistula was performed. The oral mucosa was then gently undermined approximately 3 mm around all edges of the fistula. The fascia lata graft was trimmed to size and used to reconstruct the buccal aspect of the fistula; the graft was sutured in place along the undermined edges of oral mucosa around the fistula with 3-0 polyglactin 910 in a simple interrupted pattern. After placement of the fascia lata graft, a 1-cm-diameter oral mucosal pedicle flap was created by making a circumferential incision over the adjacent oral mucosa on the lateral aspect of the fistula (Figure 6) After partial undermining of the oral mucosa, the flap was rotated while maintaining the pedicle; 3-0 polyglactin 910 was used to suture the flap in place over the previously placed fascia lata graft with simple interrupted sutures. Finally, the buccotomy incision was closed in 2 layers; 2-0 polyglactin 910 was used to close the mucosal, submucosal, and muscle layers in an inverting horizontal mattress pattern, and 2-0 polydioxanone was used to close the skin in a simple interrupted pattern.
The pony's recovery from anesthesia was unremarkable, and administration of doxycyclineq (10 mg/kg [4.5 mg/lb], PO, q 12 h for 2 weeks) and phenylbutazone (2.2 mg/kg, PO, q 12 h for 5 days) was initiated. Food was withheld for 24 hours after surgery, and then a semiliquid mash of soaked alfalfa cubes was offered 6 times/d for 4 weeks to minimize pressure on the healing tissues. By 3 days after surgery, clinical signs (ie, nasal discharge and malodorous breath) of the fistula were no longer evident. The pony was discharged from the hospital 7 days after surgery.
Fourteen days after surgery, the pony was returned to the hospital for a follow-up evaluation. The owner reported that the pony remained free of the previous clinical signs. Clinical examination revealed that the buccotomy and thigh skin incisions had healed by first intention. A subsequent follow-up examination at 4 weeks after surgery revealed that the fistula had completely healed, and endoscopic examination of the nasal cavity revealed no feed material. Accordingly, the owner was instructed to resume feeding the pony its regular diet. Twelve months later, findings at a final follow-up examination confirmed that the fistula had healed and the clinical signs had completely resolved (Figure 6).
The authors received no external funding and declare that there were no conflicts of interest.
Take 1 Advanced putty, Kerr Corp, Romulus, Mich.
Ilium Nabudone P IV, Troy Laboratories Pty Ltd, Smithfield, NSW, Australia.
Ilium Propercillin, Troy Laboratories Pty Ltd, Smithfield, NSW, Australia.
Aagent, Fatro SpA, Veterinary Pharmaceutical Industry, Bologna, Italy.
Intraflon 2, Vygon Value Life, Ecouen, France.
Eqdomin, Ourofino Saude Animal, Sao Paulo, Brazil.
Morphasol, Forte Healthcare Ltd, Meath, Ireland.
Harlton's mouth wedge speculum, Equine Dental Instruments, Elmwood, Wis.
Mepivacaine, Ceva Animal Health Pty Ltd, Glenorie, NSW, Australia.
Ilium Ketamil, Troy Laboratories Pty Ltd, Smithfield, NSW, Australia.
Bute granules, Randlab, Peakhurst, NSW, Australia.
Ilium Xylazil-100, Troy Laboratories Pty Ltd, Smithfield, NSW, Australia.
Ilium Diazepam, Troy Laboratories Pty Ltd, Smithfield, NSW, Australia.
IsoFlo, Abbott Laboratories Ltd, Maidenhead, England.
Vicryl, Johnson & Johnson International, Diegem, Belgium.
PDSII, Johnson & Johnson International, Diegem, Belgium.
Doxylag, Labatec Pharma SA, Vezia, Switzerland.
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