History

An 8-year-old 23.6-kg spayed female Border Collie was presented for evaluation of a recurrent mass on the rostral hard palate. The mass was first identified by the referring veterinarian 2 months prior to presentation after the owners observed oral bleeding. At that time, the visible mass extended from the caudal border of the incisors to the caudal border of the canine teeth bilaterally and was red, lobulated, and ulcerated in appearance. Thoracic radiographs revealed no evidence of pulmonary metastasis. An excisional biopsy was performed, and histopathology was consistent with a malignant spindle cell neoplasm with > 50 mitotic figures per 10 high powered fields. Recurrence was first noted 1 month after the initial resection, and the dog was referred for further diagnostics and treatment.

Diagnostic Findings and Interpretation

At the initial evaluation, physical examination revealed a 2 x 1.5 cm area of abnormal tissue with a well-defined 0.5 cm nodule and a 0.5 cm area of ulceration arising from the rostral hard palate caudal to the left maxillary canine tooth; both maxillary canine teeth and the left maxillary third incisor were loose. A CT scan of the head and thorax was performed, which revealed a 1.3 x 1.7 x 0.7 cm strongly heterogeneously contrast-enhancing, lobulated thickening of the rostral maxillary palatal mucosa, immediately caudal to the right incisors, with focal lysis of the third left maxillary incisor but no evidence of dorsal invasion through the maxillary or incisive bones. No evidence of regional or pulmonary metastatic disease was appreciated. Aspirates of the left and right mandibular lymph nodes showed reactive lymphoid hyperplasia, without evidence of metastasis. Surgical excision of the mass with curative intent was recommended, and the dog was presented for surgical evaluation 12 days later. At that time, the mass measured 3 x 2 cm and was ulcerated. Preoperative CBC and chemistry panel were clinically unremarkable. Bilateral rostral maxillectomy to the level of the caudal border of the first premolar teeth was recommended to allow resection of the mass with 1 cm gross margins. Reconstructive options were discussed, including the use of a cantilever suture or muzzle-shortening rhinoplasty (MSR) as a novel technique. The owner elected for MSR.

Treatment and Outcome

The dog was premedicated with fentanyl (5 mcg/kg, IV) and lidocaine (2 mg/kg, IV) and general anesthesia was induced with propofol (5.5 mg/kg, IV) and midazolam (0.1 mg/kg, IV). Constant rate infusions of fentanyl (0.2 mcg/kg/min, IV) and lidocaine (50 mcg/kg/min, IV) were initiated following induction. General anesthesia was maintained with isoflurane in oxygen during aseptic preparation and sevoflurane in oxygen in the operating room. Bilateral infraorbital nerve blocks were performed with 0.5% bupivacaine (5 mg each side). Cefazolin (22 mg/kg, IV) was administered prior to incision and repeated every 90 minutes intraoperatively.

The dog was positioned in sternal recumbency, and an intraoral approach was made to the maxilla (Figure 1). Grossly uninvolved bone dorsal to the mass was used as a deep margin rostrally. After soft tissue dissection, a sagittal saw was used to complete the rostral maxillectomy with 2 osteotomies, the first in the dorsal plane and the second in the sagittal plane, immediately caudal to the first premolar teeth. The excised segment containing the tumor was then removed (day 0).

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Immediate preoperative and intraoperative photographs detailing rostral maxillectomy in an 8-year-old spayed female Border Collie, weighing 23.6 kg, with a recurrent rostral palatal mass. A—Rostral view of the preoperative appearance of the nasal planum. B—Lateral view of the preoperative appearance of the muzzle. C—Intra-oral view of the recurrent rostral palatal mass (white arrowhead). D—An initial incision was made in the buccal mucosa, just dorsal to the gingiva and extending caudal to the first premolar teeth, at least 1 cm from the gross tumor. E—Soft tissues dorsal to the body of the incisive bone were released with monopolar electrosurgery to elevate the nasal planum and expose the rostral portion of the nasal processes. A transversely oriented mucosal incision was made in the mucosa of the hard palate prior to completion of rostral maxillectomy with a sagittal saw. Two osteotomies were made; the first in a dorsal plane through the nasal processes of the incisive bones and nasal septum (location indicated with a black arrow), and the second in a transverse plane through the maxillary bones, immediately caudal to the first premolar tooth (location indicated with a white arrow). F—Excised specimen following rostral maxillectomy, with 1 cm gross lateral margins.

Citation: Journal of the American Veterinary Medical Association 263, 1; 10.2460/javma.24.08.0509

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Following rostral maxillectomy, marked ventral deviation of the nasal planum was evident, and MSR was performed (Figures 2 and 3). The nasal cartilage and the rostral maxilla were each shortened by approximately 1 cm to reduce muzzle length and facilitate contouring. Three holes were drilled in each side of the maxilla, and absorbable sutures were preplaced in the holes and passed through corresponding locations on each side of the nasal cartilage. A 3 cm midline incision was made at the dorsal aspect of the muzzle, just caudal to the nasal planum and these sutures were passed through to the dorsal skin incision and tied on the dorsal aspect of the muzzle to anchor the nasal cartilage in direct apposition to the osteotomy site. The dorsal skin incision was closed using 3-0 poliglecaprone 25 (Monocryl, Ethicon; Johnson & Johnson Medical) in a continuous intradermal pattern, augmented with skin glue. The intraoral incision was closed using bilateral buccal advancement flaps.

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Intraoperative appearance after the rostral maxillectomy described in Figure 1, with subsequent reconstruction. A—Immediate postmaxillectomy appearance of the muzzle, demonstrating substantial ventral deviation of the nasal planum. B—Rostral view with the nasal planum retracted dorsally. The caudal portion of residual rostral nasal cartilage can be seen inverted (white arrowhead), as well as the cut edge of the palate (gray arrowhead). Approximately 1 cm of the nasal cartilage was removed using a scalpel blade and monopolar electrosurgery. C—Approximately 1 cm of the dorsal and lateral aspects of the maxillary, nasal, and incisive bones have been exposed using monopolar electrosurgery, in preparation for muzzle shortening. D—Approximately 8 to 10 mm of rostral length was removed from the nasal and maxillary bones using a high-speed drill (Hall Micro 100 Pneumatic Drill; Conmed). The bone was contoured to provide lateral projections of bone (white arrow) for direct apposition with the nasal cartilages. Six holes were drilled using the same drill caudal to the new rostral margin to allow preplacement of 2-0 polydiaxanone sutures (PDS-II, Ethicon; Johnson & Johnson Medical), which were anchored in corresponding portions of the shortened nasal cartilage (gray arrow). E—An incision was made at dorsal midline and the stay sutures were then redirected through this incision to facilitate knot tying at the dorsal aspect of the nasal cartilage (white arrowhead) and maxillary and nasal bones (black arrowhead). F—After securing the dorsal sutures, the intra-oral incision was closed in 2 layers using bilateral buccal advancement flaps (submucosal closure with 3-0 polydioxanone in a horizontal interrupted pattern; mucosal closure with polyglactin 910 (Vicryl, Ethicon; Johnson & Johnson Medical) in a cruciate mattress pattern.

Citation: Journal of the American Veterinary Medical Association 263, 1; 10.2460/javma.24.08.0509

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Illustration depicting the rostral maxillectomy and muzzle-shortening rhinoplasty (MSR) procedures described in Figures 1 and 2. A—Proposed sites of the maxillary osteotomies. B—Location of the skin incision on the dorsal aspect of the muzzle, and segments of the nasal cartilage and nasal and maxillary bones excised during muzzle shortening. C—Locations of pre-placed sutures in the nasal cartilages and through holes drilled in the nasal and maxillary bones. D—Apposition of the nasal cartilages and maxillary bones as the sutures are tied.

Citation: Journal of the American Veterinary Medical Association 263, 1; 10.2460/javma.24.08.0509

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Immediately postoperatively, the muzzle was shortened, with resultant prognathism; however, the nasal planum was positioned normally, with no overt tendency to ventral or lateral deviation (Figure 4). Recovery from anesthesia was rapid and smooth. Carprofen (2.2 mg/kg) was administered subcutaneously, and the dog was hospitalized with cefazolin (22 mg/kg, IV, q 6 h) and fentanyl (2 mcg/kg/h, IV, constant rate infusion) overnight. On postoperative day 1, mild swelling of the muzzle was evident and respiration was mildly stertorous on inhalation, with normal respiratory rate and effort, and the dog was discharged with carprofen (2.1 mg/kg, PO, q 12 h), amoxicillin–clavulanic acid (10.7 mg/kg, PO, q 12 h), trazodone (4.2 mg/kg, PO, q 8 h, as needed for sedation), and maropitant (2.6 mg/kg, PO, q 24 h, as needed for nausea). Histopathologic findings were consistent with grade 3 soft tissue sarcoma, with approximately 1 cm tumor free histologic margins.

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Short-term postoperative appearance of the dog described in Figure 1. A—Rostral view immediately postoperatively. The nasal planum is no longer ventrally deviated. The mandibular canines can now be seen as a result of the induced prognathism. B—One-day postoperative appearance. Mild swelling of the muzzle can be seen. C—Intraoral view of the palatal reconstruction at 15 days postoperatively, with acceptable healing. D—Cosmetic appearance at 15 days postoperatively, demonstrating the shortened muzzle and resolution of swelling.

Citation: Journal of the American Veterinary Medical Association 263, 1; 10.2460/javma.24.08.0509

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The dog was reassessed at 15 days and then at 5, 9, 12, and 15 weeks postoperatively. At 15 days postoperatively, the incisions appeared to be healing appropriately and no ventral nasal deviation was appreciated (Figure 4). Mild stertor was observed and suspected to be due to residual inflammation within the nasal cavities. The dog was treated with a 6-dose doxorubicin chemotherapy protocol (24 mg/m², IV, q 3 wk). During sedation for initial chemotherapy administration, the nostrils were evaluated for stenosis by passing Kelly forceps into each nare past the level of the box lock. No evidence of stenosis was appreciated. At 5 weeks postoperatively, the stertor had resolved, and good nasal airflow without deviation of the nasal planum was reported at all further reassessments and communications with the owner.

At 17 months postoperatively, the dog was presented with a 10 x 13 cm, firm, fixed mass over the caudal left shoulder, with a weight-bearing lameness of the left forelimb. Cytology of the mass performed by the referring veterinarian was consistent with soft tissue sarcoma, and pulmonary nodules were appreciated on thoracic radiography at that time. The maxillary surgery site appeared intact, with no local recurrence, respiratory concerns, or nasal deviation. The new mass was considered more likely a new primary tumor rather than metastasis of the initial maxillary sarcoma. Due to the poor prognosis with metastatic disease, palliative supportive care was elected, and the dog was euthanized by her primary veterinarian at 19 months postoperatively.

Comments

Extensive bilateral rostral maxillectomy can result in loss of the underlying support of the nose, causing ventral deviation of the nasal planum that can compromise airway function and cosmesis.^1,2 Previously described techniques to mitigate deviation include drawing the nasal planum caudally through imbrication, external splinting of dorsal soft tissues, excision of an elliptical wedge of dorsal nasal skin, and anchoring of the dorsal aspect of the nasal cartilage to the maxillary bone using a cantilever suture.^1,3,4 These techniques primarily provide support at the dorsal aspect of the nasal planum, and, in the authors’ experience, are at risk of stretching and failure over time. This case report describes the use of MSR, a novel reconstructive technique in which the muzzle length was shortened following maxillectomy, reducing the lever arm at the repair and allowing contouring to facilitate support of the nasal planum both dorsally and laterally.

An important sequela of MSR is prognathism, which, if pronounced, may be cosmetically unacceptable to some owners, and could result in difficulty prehending food or trauma of the caudally displaced maxillary lips by the mandibular canine teeth. The dog described in this case report had a meso- to dolichocephalic conformation, and accommodated the degree of muzzle shortening without complication, but results may vary for dogs with other facial conformations, or which require more extensive resection. The clinical utility of MSR cannot be determined from a single case, and further study of the feasibility of application of the technique in the context of various facial conformations is warranted. While issues such as failure of stabilization or stenosis were not encountered, these adverse events should be a focus of any future clinical research into this technique. Muzzle-shortening rhinoplasty provided a good long-term functional and cosmetic outcome in the described dog, without complications, and may be a useful option for muzzle reconstruction and nasal planum support after bilateral rostral maxillectomy in dogs.

Disclosures

The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.

Funding

The authors have nothing to disclose.

ORCID

V. A. Herron https://orcid.org/0000-0001-8901-6954

O. T. Skinner https://orcid.org/0000-0002-3765-429X