Brachycephalic syndrome comprises a combination of canine upper respiratory tract abnormalities that result in upper airway obstruction (7,17). The aforementioned syndrome includes stenotic nares, elongated soft palate, everted laryngeal ventricles, laryngeal collapse, and hypoplastic trachea (7,12,17). Stenotic nares and elongation of the soft palate are congenital abnormalities that contribute to upper airway obstruction. Laryngeal saccule eversion is attributable to the negative pressure in the upper airways. Moreover, these everted saccules may instigate airway obstruction (12). Tracheal hypoplasia causes increased airway resistance. Chronic airway obstruction in brachycephalic breeds can lead to severe laryngeal edema and laryngeal collapse in severe cases. The increased negative pressure required during inspiration may bring about secondary changes, including laryngeal collapse, which involves three stages: stage 1, everted laryngeal saccules; stage 2, loss of rigidity and medial displacement of the cuneiform processes of the arytenoid cartilage; and stage 3, collapse of the corniculate processes of the arytenoid cartilages with loss of the dorsal arch of rima glottidis (12).

Several surgical procedures and techniques can be employed to correct brachycephalic syndrome. However, the postoperative complications and prognosis must be taken into consideration. Bleeding is one of the most common intraoperative complications encountered during surgical procedures. Various techniques such as compression with a gauze, hemostat forceps, epinephrine, electrocautery, and the application of ultrasonic scalpels are used to achieve intraoperative hemostasis. In particular, the harmonic scalpel (harmonic focus^®, Ethicon, US) is a very efficient instrument to achieve hemostasis that converts the tissue protein into a sticky coagulum by way of the principles of ultrasound.

The precise objective of the current, retrospective study was to assess the short-term prognosis and probable postoperative complications associated with the surgical correction of elongated soft palate using a harmonic scalpel. Furthermore, the present study compared the postoperative complications associated with the correction of everted laryngeal saccules using harmonic scalpel and traditional surgery using Metzenbaum scissors. The postulated hypothesis was that the harmonic scalpel would facilitate the correction of elongated soft palate and everted laryngeal saccules.

Criteria for selection of cases

The medical records from Helix Animal Medical Center and Keunmaum Animal Medical Center were reviewed, in order to identify all the dogs that were hospitalized and underwent staphylectomy with harmonic scalpel during the time period from 2016 to 2020. All the dogs displayed the clinical signs of brachycephalic syndrome, such as noisy breathing, exercise intolerance, dyspnea, and gastrointestinal signs. The current study included the dogs with complete medical records with documented upper airway examination findings comprising elongated soft palate. The dogs may or may not have undergone surgical management by way of laryngeal sacculectomy using Metzenbaum scissors or harmonic scalpel and the dogs that did not receive surgical intervention were excluded from the present study.

Anesthetic protocol

All the dogs underwent preoperative fasting for a duration of approximately 12 h prior to the commencement of the surgical procedure. All the canine patients were premedicated using ketamine (5 mg/kg, administered intravenously [IV], Ketamine HCl Injection^®; Huons, Korea) and acepromazine (0.03 mg/kg, IV, Sedaject^®; Samu Median, Korea) (17 dogs) or butorphanol (0.2 mg/kg, IV, Butophan Injection^®; Myungmoon Pharm, Korea) and midazolam (0.2 mg/kg, IV, Midazolam Inj^®; Bukwang, Korea) (4 dogs). The administration of atropine (0.03 mg/kg, IV, Atropine Sulfate Injection^®; Jeil, Korea) was performed in situations wherein the heart rate dropped below the low-normal level. Preoxygenation was performed with 100% O2 before the induction of anesthesia. Prophylactic antibiotic administration was done using cefazoline (25 mg/kg, IV, Cefazoline Injection^®; Chongkundang, Korea). Normal saline was administered as intravenous infusion at 10 mL/kg/h through the cephalic vein during the entire surgical procedure.

Subsequent to premedication, oropharyngeal and laryngeal examinations were performed prior to endotracheal intubation (following the IV administration of 3 to 6 mg/kg of propofol). The examinations involved assessment of the elongated soft palate, everted laryngeal saccules, and laryngeal collapse. Anesthesia was induced via the IV administration of propofol and maintained by the administration of isoflurane (Ifran^®; Hana Pharm, Korea) via a cuffed endotracheal tube. The heart rate, body temperature, percutaneous blood oxygen saturation (SpO2), and end-tidal carbon dioxide (ETCO2) level were monitored during anesthesia. Application of ophthalmologic ointment (Liposic^®; Bausch+Lomb, Germany) was performed to protect the eyes from drying out during the procedure.

Surgical technique

Staphylectomy

All the surgical procedures were performed by the same surgeon in a sterile manner and the surgical instruments were sterilized using an autoclave or hydrogen peroxide plasma. All the dogs were positioned in sternal recumbency and the head and neck were positioned to facilitate the surgical approach through the oral cavity. Subsequently, a pole were placed anteriorly on either side of the surgical table. A bandage was placed around the maxillary canine teeth (Fig. 1A) and tied to the pole to suspend the upper jaw. The level of palatal resection was assessed by means of minimal traction on the palate or tongue. Stay suture or Allis tissue forceps was placed on the caudal edge of the palate on the midline and used to retract the palate rostrally (5) (Fig. 1B). Subsequently, a palatal incision was placed at the level of the caudal border of the tonsils using a harmonic scalpel (Harmonic Focus^®, Ethicon, US). In the case of large dogs, simple continuous pattern with monofilament absorbable suture (Maxon 4-0, Covidien, Massachusetts, USA) was used to appose the oral and nasal epithelial surfaces of the cut edge of the soft palate (Fig. 1C).

Figure 1. The surgical technique of staphylectomy using harmonic scalpel. (A) The dog was positioned in sternal recumbency. A bandage was placed around the maxillary canine teeth and fastened to the poles to suspend the upper jaw. (B) Serrated tissue forceps were used to retract the caudal end of the soft palate and two stay sutures were placed beneath the site of resection (yellow dotted line) to facilitate the incision. A palatal incision placed at the level of the caudal border of the tonsils. (C) The cut edge of the soft palate was closed using simple continuous suture.

Sacculectomy

The endotracheal tube was retracted dorsomedially, in order to visualize the laryngeal saccule. The everted saccules were grasped using Debakey forceps and transected by means of long-handled, curved Metzenbaum scissors or harmonic scalpel (harmonic focus^®, Ethicon, US) (Fig. 2). After transection using Metzenbaum scissors, it was gently pressed to control the hemorrhage. The same procedure was repeated on the contralateral side (4).

Figure 2. The surgical technique of sacculectomy. (A) Visualization of the laryngeal saccules (white arrow). (B) Determination of the incision line (yellow dotted line). (C) Laryngeal saccules were grasped by means of a Debakey forceps and transected using long-handled, curved Metzenbaum scissors or a harmonic scalpel. (D) A single incision placed on one side of the saccule. (E) The appearance of vocal cords after sacculectomy.

Surgical correction of stenotic nares

Wedge resection is a frequently performed surgical procedure. A lateral, vertical, or horizontal wedge of tissue can be resected from the dorsal lateral nasal cartilage, including the overlying mucosa and epithelium. A single incision that allowed partial amputation of the wing of the soft tissue cranioventral to the dorsolateral nasal cartilage (Fig. 3) was placed. Single layer closure was performed using 5-0 monofilament round needle suture material (Blue nylon^®, Ailee, Korea) with simple interrupted sutures.

Figure 3. The surgical correction of stenotic nares. Wedge resection was performed and closure was done with simple interrupted sutures using 5-0 monofilament round needle suture material.

Postoperative care

Postoperatively, the dogs were monitored on a daily basis to detect the signs of postoperative complications. The postoperative status of the subject, such as the heart rate, temperature, respiratory rate, and breathing pattern were monitored and oxygen was administered. Postoperative antibiotics, analgesics, and H2 blockers were administered. If required, dexamethasone (0.3-0.5 mg/kg SC) was administered to prevent postoperative laryngeal edema. Dogs that underwent staphylectomy were hospitalized for one day, whereas the dogs that underwent sacculectomy were discharged three days after the surgical procedure. The owners were provided with instructions to monitor the respective dogs for signs of breathing or gastrointestinal problems, to limit exercise for a few days, and to maintain a cool environment around the dog.

Review of medical records

The data obtained from the review of medical records included signalment, reason for evaluation, medical history, and the findings of physical examination including the presence of stertor or stridor, dyspnea, respiratory distress, exercise or stress intolerance, gagging or coughing, vomiting, collapse, or hyperthermia. Furthermore, the current study obtained data regarding the results of the laryngoscopic examination of the pharynx and larynx, which indicated the presence or absence of stenotic nares and elongated soft palate, and the stage of laryngeal collapse (8). Moreover, the present study obtained additional information, such as data regarding the procurement of thoracic radiographs, presence of hypoplastic trachea, the occurrence of intra- or postoperative complications, and details regarding the complications encountered. The owner’s perception of the patient’s response to surgery was documented through telephone interviews on the first, third, and seventh after discharge from the hospital. The interview was continued until the complications were resolved in the patients with postoperative complications.

Statistical analysis

Data collected from the medical records were analyzed and percentages for each value were calculated. The linear-by-linear association and Fisher exact test were used to evaluate for associations between gender and occurrences of the laryngeal collapse, and ages and occurrences of the laryngeal collapse, respectively. p values less than 0.05 considered as the statistical significance and all statistical analysis was conducted using SPSS Statistics ver. 25.0 (IBM Corp., Armonk, NY, USA).

The breeds were English bulldog (10 [47.6%] dogs), French bulldog (2 [9.5%] dogs), Pug (1 [4.76%] dogs), American bully (1 [4.76%] dogs), and Boston terrier (1 [4.76%] dogs), Chihuahua (1 [4.76%] dogs), Pomeranian (1 [4.76%] dogs) and Maltese (4 [19.04%] dogs). English bulldogs were the most common breeds among the 21 study dogs. In the study population, there were 12 (57.14%) male and 9 (42.85%) female dogs; 7 (58.3%) dogs were sexually intact males, and 4 (44.5%) were sexually intact females. There was no significant association between gender and occurrences of laryngeal collapse (p = 0.764). Various age group appeared, and the most common age among the 21 study dogs were 2 years (5 [23.8%] dogs). The age range varies from 10 months to 10 years old. The mean age was 3.7 years (Table 1). Dogs under 3.7 years, mean age, were significantly more likely to develop laryngeal collapse (12/17 [70.6%], p = 0.021), but not occur in dogs older than 3.7 years. The mean age of dogs with postoperative complications was 1.9 years and the mean age of the rest was 3.2 years.

Table 1 . Breed, sex, age, concurrent diseases, presence of laryngeal saccules, surgical technique, and postoperative complications pertaining to the subjects.

No.	Breed	Sex	Age	Concurrent diseases			Postoperative complications (duration)
				Stenotic nares (surgical technique)	Stage of laryngeal collapse (surgical technique)	Other comorbidities
1	English bulldog	M	3 Y		I (Harmonic)	Bronchitis, tracheal hypoplasia	Gagging, vomiting (7 days)
2	English bulldog	F	10 M		I (Harmonic)	Mild pneumonia, segmental megaesophagus	Gagging, vomiting (10 days)
3	English bulldog	M	14 M		I (Harmonic)
4	English bulldog	M	2 Y		I (Harmonic)
5	English bulldog	M	1 Y		I (Metzen)
6	English bulldog	M	1 Y		I (Metzen)
7	English bulldog	M	16 M		I (Metzen)
8	English bulldog	F	3 Y		I (Metzen)
9	English bulldog	F	1 Y	O	I (Metzen)	Chronic bronchitis
10	French bulldog	SF	2 Y	O	I (Metzen)		Gagging, vomiting (2 days)
11	French bulldog	SF	10 M	O	I (Not done)
12	American bully	F	2 Y		I (Not done)
13	English bulldog	M	2 Y		-	Bronchitis
14	Boston terrier	CM	3 Y	O	-	Tracheal hypoplasia
15	Chihuahua	SF	2 Y		-
16	Maltese	SF	7 Y		-
17	Maltese	CM	10 Y		-	Esophageal tumor, tracheal collapse, IBD
18	Maltese	SF	10 Y		-	Nasal tumor	Pharyngeal edema (1 day)
19	Maltese	M	1 Y		-
20	Pomeranian	CM	2 Y		-	Chronic bronchitis
21	Pug	M	9 Y		-

All dogs were performed staphylectomy using harmonic scalpel..

M, male; F, female; CM, castrated male; SF, spayed female; I, stage 1 of laryngeal collapse; IBD, inflammatory bowel disease..

Noisy breathing (snoring and stridor) was the most common clinical sign (18 [85.7%] dogs). Other clinical signs among the 21 dogs included exercise intolerance (8 [38%] dogs); dyspnea (7 [33.3%] dogs); gastrointestinal sign (4 [19%] dogs). Of the 21 dogs, 11 had concurrent disease (Table 1).

Elongated soft palate was the most common abnormality (21 dogs [100%]) observed in the current study. Among the 21 canine subjects, stenotic nares and everted saccules were diagnosed in four (19%) and twelve (57%) dogs, respectively. The most common combination of abnormalities was elongated soft palate with everted saccules that was identified in nine (30%) dogs. Elongated soft palate alone was present in eight dogs (38%). None of the subjects presented with everted saccules alone. All the canine patients with elongated soft palates underwent surgical correction of the same, while two dogs with everted saccules did not undergo sacculectomy. The most common breed in the current study was the English Bulldog, comprising ten among the twenty-one dogs with elongated soft palates, one among the four with stenotic nares, and nine among the twelve dogs with everted saccules. The diagnoses and combinations of surgical procedures performed on the 21 dogs involved in the present study are presented in Table 1.

Elongated soft palate was the most common abnormality (21 dogs [100%]) observed in the current study. Among the 21 canine subjects, stenotic nares and everted saccules were diagnosed in four (19%) and twelve (57%) dogs, respectively. The most common combination of abnormalities was elongated soft palate with everted saccules that was identified in nine (30%) dogs. Elongated soft palate alone was present in eight dogs (38%). None of the subjects presented with everted saccules alone. All the canine patients with elongated soft palates underwent surgical correction of the same, while two dogs with everted saccules did not undergo sacculectomy. The most common breed in the current study was the English Bulldog, comprising ten among the twenty-one dogs with elongated soft palates, one among the four with stenotic nares, and nine among the twelve dogs with everted saccules. The diagnoses and combinations of surgical procedures performed on the 21 dogs involved in the present study are presented in Table 1.

The current results show that harmonic scalpel can be safely used for the resection of elongated portion of the soft palate in dogs with brachycephalic syndrome and upper airway obstruction. The current study did not observe any serious complications associated with the surgical procedure. Among the three patients who presented with postoperative complications, two underwent sacculectomy with harmonic scalpel (2/4, 50%) and one underwent sacculectomy using Metzenbaum scissors (1/6, 17%). The complications persisted for seven and ten days in the two dogs that underwent sacculectomy with harmonic scalpel, and for two days in the dog that underwent sacculectomy using Metzenbaum scissors.

The English bulldog was the most common breed in the present study. The demographic results of the current study were concurrent with the results reported by previous studies (12,14,16), except for the commonest breed in the study population, which was reported to be the French Bulldog in one study (14) and the King Charles Cavalier Spaniel in another study (16). The most frequently detected abnormalities concerning the dogs involved in the present study were similar to the results reported by previous canine studies (12,14,16). The mean age of the subjects included in the present study was 27.5 months which is concurrent with the results reported by previous studies (9,14,15). In the mean age of dogs less than 3.7-year-old, the incidence of laryngeal collapse was statistically significantly higher. Howerver, there was no significant difference between gender and occurrences of laryngeal collapse. The mean age of the dogs that underwent sacculectomy and presented with postoperative complications was under 3.7-year-old, which may be indicative of the possibility that more severely affected dogs might undergo clinical evaluation at a younger age.

In line with the results reported by several previous studies, the most common clinical symptom observed in the current study was snoring and stridor (3,15). Generally, snoring is associated with the presence of excessive tissue in the upper region of the airway tract, such as the occurrence of elongated soft palate, whereas stridor is usually associated with a narrowed or strictured upper airway, such as the clinical scenarios attributable to laryngeal collapse or paralysis (15). Although certain clinical signs are supportive of the various components of brachycephalic syndrome, the diagnosis is confirmed through oropharyngeal examination (15). Similar to the results reported in previous literature, the present study observed other symptoms including exercise intolerance, dyspnea, and gastrointestinal signs (13,14). Moreover, a previous study (14) has reported that stimulation of the autonomic nervous system associated with high upper airway pressure can stimulate a centrally invoked vomiting response in some dogs. An elongated soft palate can cause gagging, because it extends caudally to the rima glottidis, and there are several gastrointestinal tract disorders that commonly coincide with chronic respiratory compromise in dogs. In addition, even the dogs that do not display any clinical symptoms associated with gastrointestinal tract disorders may have endoscopic lesions and the severity of pathological changes surpass the expected levels (14).

The typical complications associated with the surgical correction of elongated soft palate and everted laryngeal saccules include edema of the airway, vomiting, regurgitation, and aspiration. Other complications include persistent upper airway stertor/stridor, recurrence of less extreme upper airway signs, and voice changes. Previous studies have reported that the long-term outcomes pertaining to the surgical correction of brachycephalic disorder was generally good with a mortality rate below 5% (1,13,15,16,18).

A previous study that compared the effects of the application of CO₂ laser, diode laser, and monopolar electrocautery for resection of the soft palate in dogs (2) reported that the global postoperative mortality was 3.3% (n = 2) and both the dogs belonged to the diode group. Furthermore, two other dogs in the diode group required tracheostomy 1 h and 10 h after the surgical procedure. In addition, one dog in the CO₂ group presented with bronchopneumonia on the first postoperative day. Another previous study (6) has reported that the overall major complication rate was 23% (14/60), including five (5/26, 19%) and nine dogs (9/34, 26%) in the CO₂ laser and bipolar vessel device groups, respectively.

The current study did not observe any postoperative complications in 11 dogs that underwent staphylectomy using the harmonic scalpel did not cause postoperative complications. Although the current study did not record or assess the duration of surgical procedures operation time was not measured in our study, in accordance with the results reported in previous literature according to another study, staphylectomy using harmonic scalpel required a time period of took 5 m (10) without complications. Hence, usage of a harmonic scalpel for the resection of elongated soft palate may be an effective alternative to the application of CO₂ laser, diode laser, electrothermal, or traditional resection methods.

Data regarding the prognosis with reference to the use of surgical instruments in sacculectomy are rarely reported in literature. Although the prognosis of laryngeal saccule resection with harmonic scalpel was thought to be good, the complications (gagging and vomiting) persisted for a longer duration of time and the traditional method of resection had a better prognosis. Unlike soft palates, the laryngeal saccules are attached to the surrounding tissue and offer a narrow range of maneuvers to manipulate the surgical instruments. Hence, application of harmonic scalpels warrant caution, in order to avoid unintended thermal damage to the surrounding tissue during surgery. Moreover, literature states the assumption that lateral thermal damage or histopathological changes instigated by the harmonic scalpel may prolong the duration of complications (11).

As per the results reported by a previous study (2), the duration of hospitalization was 2.45, 2.8, and 3 days in the CO₂, electrocautery, and diode groups. In the current study, the dogs that underwent staphylectomy using harmonic scalpel were discharged within one day. The duration of hospitalization was prolonged after sacculectomy and in the event of complications, the period of hospital stay was extended until the resolution of symptoms.

The present results do not present statistical significance, owing to the inadequate sample size. The scenario warrants further research regarding the effects of the application of harmonic scalpels in oropharyngeal surgery with larger samples.

This report summarizes work contained within a thesis submitted by J.I. Shin to fulfill the requirements for a MSc degree.

The authors have no conflicting interests.