Introduction

The popularity of brachycephalic breeds has risen significantly in recent years. In particular, French Bulldogs have increased by 300% through kennel club registrations over the past 10 years in the United Kingdom.¹

The English Bulldog, French Bulldog, and Pug have especially increased in popularity and are classified as “extreme brachycephalic breeds.”^2,3 Extreme brachycephalic breeds have been noted to die at a younger age than other breeds, with a higher proportion of deaths related to upper respiratory disorders.² Despite the increase in popularity of brachycephalic breeds, many owners are unaware of the conformation‐associated health risks related with these breeds, which may result in unrealistic expectations when pursuing treatment.^{1, 4–6}

Brachycephalic obstructive airway syndrome (BOAS) is a term that describes several conformational abnormalities leading to respiratory distress, which often requires surgical intervention to alleviate clinical signs.^5,7,8 Several anatomical changes have been documented to be associated with brachycephalic breeds. Anatomic abnormalities associated with BOAS include macroglossia, stenotic nares, aberrant nasopharyngeal turbinates, elongated soft palate, excessively thickened soft palate, hypoplastic trachea, and redundant pharyngeal folds.^{7, 9–11} Macroglossia in brachycephalic breeds creates lower air‐to‐soft tissue ratios within the oropharyngeal and nasopharyngeal regions, which can contribute to upper airway obstruction.¹² Although one study documents increased nasal mucosal contact points and more prevalent aberrant turbinates in brachycephalic dogs, no correlation could be made between these findings and brachycephalic airway syndrome due to lack of knowledge of these dogs’ clinical signs.¹¹ It is also unknown if the thickening of the soft palate is a primary structural abnormality or a secondary change; however, it is considered a component in severe BOAS.^9,10 Combinations of this altered anatomy lead to increased resistance during inspiration.¹⁰ Brachycephalic dogs must create a higher negative pressure distal to the resistance, through labored breathing, to maintain appropriate oxygen levels.¹⁰ Secondary manifestations of increased airway resistance include everted laryngeal saccules, tonsillar eversion and hyperplasia, and laryngeal collapse.^7,10 Gastrointestinal disease is common in many brachycephalic breeds and is likely associated with negative intra‐thoracic pressure generated during inspiration.^7,13,14 It is not completely understood which anatomic change or a combination thereof leads to the most severe clinical signs.

Clinical signs in dogs with BOAS may include both respiratory and gastrointestinal signs. Reported clinical signs may include exercise intolerance, heat intolerance, sleep apnea, increased respiratory rate and effort, stertor or stridor, regurgitation, gagging, vomiting, nausea, dyspnea, and when severe, may progress to syncope, collapse, heat stroke, and death^{1,3,5–7,10,13} (Video 7.1). A correlation has been established between BOAS and gastrointestinal signs in the extreme brachycephalic breeds, with French Bulldogs having the highest prevalence of presurgical regurgitation and vomiting.¹³ It is important that veterinarians recognize that gastrointestinal signs are often a sequela of BOAS, requiring surgical intervention through corrective upper airway surgery. Gastroesophageal reflux, vomiting, or regurgitation can lead to aspiration pneumonia.⁷ There are clinical signs spanning from “normal” or a “normal variant” for a brachycephalic dog to a dog clinically affected with BOAS.³ A normalization phenomenon exists that describes the acceptance of some chronic and highly breed‐associated conditions as normal.⁶ In a questionnaire‐based study, 58% of owners reported a high frequency and severity of clinical signs in their dogs without perceiving them to have a breathing problem.⁶ Lack of recognition of clinical signs indicating disease may result in a lack of treatment until clinical signs progress and negatively affect an animal’s welfare and outcome.⁶ Since clinical signs are progressive, it is paramount that veterinarians recommend brachycephalic breeds seek early surgical intervention, even if not mentioned by the client as a concern, prior to the development of chronic and irreversible negative effects of BOAS or a respiratory crisis.^3,6,7

A thorough clinical history should be obtained, which can provide significant insight into any underlying problems. It is imperative to identify signs of both respiratory and gastrointestinal disease. It should be noted that lack of clinical signs does not equate to lack of conformational changes. One study evaluating brachycephalic dogs without clinical signs of upper airway disease found that all dogs had obvious redundancy or moderate to severe elongation of the soft palate.¹⁵ Another study found that the degree of nasopharyngeal occlusion by the soft palate evaluated by computed tomography (CT) was not correlated to the severity of clinical signs.¹⁶ The severity of respiratory signs influences the severity of gastrointestinal signs and vice versa. Brachycephalic dogs exhibiting respiratory signs have evidence of gastrointestinal disease (esophageal, gastric, or duodenal) on histologic evaluation whether or not gastrointestinal signs or endoscopically visible lesions are present. Gastroesophageal reflux can contribute to upper respiratory problems by producing upper esophageal, pharyngeal, and laryngeal inflammation.¹⁷ It is shown that treatment of upper gastrointestinal disease prior to anesthesia can decrease the complication rate associated with corrective upper respiratory surgery and improve prognosis.¹⁸

Due to the progressive nature of BOAS and increased risk of post‐operative complications when dogs present for surgery on an emergent basis, it is paramount that dogs have early surgical intervention, prior to severe clinical signs and development of irreversible secondary changes.^7,19 Studies document the presence of severe secondary changes in dogs younger than one year of age.²⁰ One study, where all dogs were at least one year of age, documented that performing surgery at a younger age was associated with an increased likelihood of a poorer prognosis after surgery.⁸ This is likely related to more severe disease in this population and supports performing surgery as early as possible. Dogs that have surgery at a younger age have significantly fewer complications, with the odds of developing complications increasing with each year of age.⁷ Although the benefit of prophylactic surgery is not fully known, the author recommends and routinely performs laryngeal examination, and if warranted, corrective airway surgery, under the same anesthetic episode of surgical sterilization. The author recommends surgical intervention prior to obvious clinical signs to improve quality of life and to attempt to slow the progression of diseases, between the age of six months and one year.

How to determine which patient would benefit from corrective surgery, including which procedures, remains controversial. This is generally based on clinical signs and laryngeal examination findings. The prognosis appears to be related to the severity of airway pathology present and not the surgical procedure(s) performed. The author routinely performs surgical correction of all identifiable abnormalities of the nares, palate, saccules, and tonsils. Although most dogs improve after surgery, it is known that clinical signs, such as snoring while sleeping, stertor/stridor while awake, and dyspnea, can persist after surgery.²¹ Decreasing risk factors that can be controlled, such as obesity, are paramount.^4,17,22 Therefore, lifelong lifestyle changes are warranted despite surgery, such as weight management to maintain a slim body condition and avoidance of extreme heat.

A numeric scoring system, the BOAS index, has been established in three breeds (Pug, French Bulldog, and Bulldog) to reflect the severity of the disease and to assess the outcome after surgery.²² This requires whole‐body barometric plethysmography (WBBP), which is noninvasive, but may not be available to most clinicians. A preoperative brachycephalic risk (BRisk) score has been developed to predict the risk of major complications or death objectively and accurately in dogs undergoing corrective surgery for BOAS. There are six variables that are each independent predictors of outcome that make up the BRisk score: breed, history of airway surgery, additional planned procedures (other than airway surgery), body condition score, admission clinical findings regarding the severity of airway compromise, and admission rectal temperature. Dogs with a BRisk score >3 are 9.1 times greater risk for a negative outcome than dogs with a low score (<3). This score can help clinicians set realistic expectations and assist owners in their decision‐making process.⁴

Diagnostics

A general physical examination and a minimum database should be performed. Blood samples should be collected for complete blood count and serum biochemical analysis to screen overall health. Venous or arterial blood gas samples provide important information about pH, blood oxygen, and carbon dioxide (pv‐/paCO₂) concentrations prior to general anesthesia, which can be serially monitored during surgery and in the postoperative period. Brachycephalic dogs are noted to have lower arterial blood oxygen and higher arterial CO₂ levels than non‐brachycephalic breeds.²³

Three‐view thoracic radiographs are obtained to evaluate for the presence of pneumonia, pulmonary edema, hypoplastic trachea, and/or hiatal hernia.¹⁴ French Bulldogs appear to have a high prevalence of hiatal hernia.²⁴ The author routinely performs thoracic radiographs on the day of surgery, so the lungs are determined to be free of pneumonia prior to anesthesia (Figure 7.1). Pneumonia can complicate the balance between ventilation and perfusion and potentially worsen with anesthesia,²⁵ therefore, consideration should be given to postponing corrective surgery in the presence of pneumonia.

More advanced imaging, such as CT and endoscopy, can be considered but are likely limited to specialty hospitals, and cost may be prohibitive for some. The majority of anatomic abnormalities to be evaluated for surgery will be based on a lightly sedated oropharyngeal‐laryngeal examination. The author prefers to perform the pharyngeal‐laryngeal examination on the day of surgery, preventing a separate sedative episode, for which untreated brachycephalic patients may have difficulty recovering. Aberrant nasopharyngeal turbinates require CT and endoscopy for diagnosis and treatment, respectively.^26,27 Upper gastrointestinal endoscopy may be considered for dogs with persistent gastrointestinal signs after corrective BOAS surgery if medical management techniques are considered unsuccessful.

Perioperative Considerations

Medical treatment is recommended to decrease the risk of gastroesophageal reflux and aspiration pneumonia by decreasing perioperative upper gastrointestinal signs of nausea, vomiting, and regurgitation. There is an increased frequency of regurgitation after surgical treatment of BOAS, especially in dogs with preoperative regurgitation.²⁸ Multimodal treatment with combinations of antiemetics, prokinetics, antiacid gastroprotectants, opioids, anxiolytics, and anti‐inflammatories are recommended. There is no known ideal protocol, and the combination of medications will depend on the severity of clinical signs, patient temperament, drug availability, and clinician comfort with certain protocols¹⁴ (Table 7.1).

The effect of maropitantⁱ in preventing nausea and vomiting when administered one hour prior to pre‐medication is well established.^29,30 Maropitant also has the added value of reducing the minimum alveolar concentration of sevoflurane in dogs.³¹ The author administers maropitant prior to pre‐medication then every 24 hours while hospitalized and only if needed after the patient is discharged.

Although reflux can be influenced by anesthesia, the high prevalence of presurgical gastrointestinal signs in addition to endoscopic changes suggests a chronic gastroesophageal reflux in brachycephalic breeds.^13,17,32 Pre‐ and postoperative antiacid treatment improves digestive clinical signs and lesions in dogs undergoing corrective surgery for BOAS and is recommended in dogs without obvious clinical signs.³² The author typically gives omeprazole on the morning of surgery if no gastrointestinal signs are noted. If preoperative regurgitation is noted or suspected to occur frequently (multiple times weekly or daily), the author treats with omeprazole and cisapride for a minimum of two to four weeks prior to surgery until gastrointestinal signs are minimized or resolved.

The postoperative effects of ileus, such as vomiting, decreased tolerance of oral diets, and prolonged recovery from surgery, can be considered detrimental in a brachycephalic patient. Because the side effects of ileus are similar to upper gastrointestinal signs in brachycephalic breeds, it may be difficult to distinguish between the worsening of preexisting GOR and the effects of postoperative ileus. Therefore, efforts should be made to mitigate any effects of postoperative ileus. Administration of both a gastroprotectant and prokinetic postoperatively minimized vomiting, regurgitation, and reflux in one study.¹⁸ Ultrasound can be utilized to evaluate intestinal motility in dogs with suspected ileus.³³ The author administers omeprazole and cisapride for two to four weeks postoperative if frequent (multiple times daily) regurgitation is noted after surgery.

Nebulized epinephrine causes a clinically significant reduction in the BOAS index in preoperative dogs with a BOAS index of >70% and in dogs recovering from BOAS surgery purportedly through reduction of mucosal edema.³⁴ While WBBP needed to measure the BOAS index may not be readily available to most, epinephrine nebulization has minimal side effects, so it can be performed without knowledge of the patient’s BOAS index. The most notable side effect in one study was nausea, which could be due to the medication itself or from stress during administration.³⁴ Although nausea could be due to stress, it is also recognized as a clinical sign with underlying gastroesophageal reflux and may be associated with the brachycephalic population at hand. Nebulization should be discontinued should it present obvious stress to the patient. The author typically initiates epinephrine nebulization in the postoperative period immediately after extubation then every 6 hours for 24 hours, which is when most patients are being discharged. Some clinicians do not continue this treatment after 24 hours because of a rebound phenomenon of worsening stridor in children with croup after treatment with nebulized adrenaline. Although a rebound phenomenon has been suggested in children, a review of the literature established that no study has reported the symptoms as being worse than baseline, and the re‐emergence of symptoms is less marked when children receive nebulization concurrently with steroids.³⁵

Most literature suggests the use of corticosteroids during the perioperative period to reduce surgery‐induced and postoperative (panting) pharyngeal swelling and edema, however, controlled evidence is lacking. The author administers one dose of corticosteroids 20 minutes prior to surgery, and if postoperative obstruction is a concern related to pharyngeal edema, additional doses are repeated as needed.

Sedative‐anxiolytic drugs in combination with opioids are recommended, however, the desired effect can also relax the smooth muscle of the nasopharyngeal and oropharyngeal region risking further obstruction.³⁶ The author prefers drugs that are reversible with a short duration of action and can be administered as a constant infusion (butorphanol and dexmedetomidine), which allows for these drugs to be titrated quickly up or down to achieve the lowest dose required without excessive sedation.

Brachycephalic breeds have lower than normal arterial oxygen concentrations at rest compared to non‐brachycephalic dogs.²³ Preoxygenation for three minutes prior to general anesthesia increases the time to desaturation.³⁷ Brachycephalic dogs may particularly benefit from preoxygenation as upper airway obstruction is common and intubation can be more difficult, delaying a patent airway.¹⁴ If a face mask to deliver oxygen is stressful, the mask can be removed to deliver oxygen from the end of the anesthetic tubing, allowing some distance between the pet and the oxygen delivery system if needed. Anxiolytic drugs are administered as needed preoperatively and induction should occur rapidly.

The initial 12–24 hours of recovery is considered the high‐risk period for the brachycephalic patient, particularly because of the possibility of airway obstruction.^7,25 Brachycephalic patients recovering from surgery should be placed in sternal recumbency, with the head slightly elevated, and remain intubated until their endotracheal tube is no longer tolerated.^14,25,38 Opioids and anxiolytics should be used to obtain a calm state without excessive sedation (Table 7.1). Oxygen should be provided to any patient that shows increased respiratory effort. Clinicians should be prepared with induction drugs, endotracheal tubes, and a laryngoscope for emergency reintubation in the presence of upper airway obstruction. If a postoperative obstruction occurs after BOAS corrective surgery, the author typically reintubates, assessing the larynx for the cause of obstruction. The author will treat with additional corticosteroids and anxiolytics, allowing a more prolonged recovery. Temporary tracheostomy should be considered if additional treatment for postoperative swelling, pain, and anxiety is considered ineffective after re‐attempting extubation.

Stenotic Nares

Stenotic nares are a congenital malformation of the nasal cartilage, resulting in medial collapse and narrowing of the external nares^39,40 (Figure 7.2). The decrease in the transverse diameter of the nares leads to increased negative upper airway pressures to overcome the increased resistance in airflow.⁴⁰ There are several surgical techniques that have been described for the management of stenotic nares. All techniques can be performed with a scalpel blade, electrocautery, or CO₂ laser.

Several wedge resection (alarplasty or alaplasty) techniques (vertical, horizontal, lateral) have been described, removing wedge‐shaped portions of the wing of the nostril and underlying alar fold, requiring suture to appose the nasal epithelium^39,40 (Figure 7.3a,b). When using a blade for these techniques, hemorrhage occurs rapidly, which may impair visibility.⁴¹ Hemorrhage is controlled during surgery with direct pressure using a sterile cotton‐tipped applicator or gauze and typically resolves once the wound is sutured. A punch resection alarplasty is similar to the wedge techniques but utilizes a dermatological punch biopsy toolⁱⁱ to remove a circular plug of tissue in the ala nasi, which is then sutured closed. With each of these techniques, the nares are widened by narrowing the thickness of the alar nasi, removing tissue to the level of the alar fold.^42,43

Vertical Alar Wedge Resection – Surgical Technique

The patient is placed in sternal recumbency with the chin elevated slightly. The most ventromedial aspect of the alar wing (alar fold) is grasped at the level of the proposed tissue to be removed (Figure 7.4). The author uses a rat tooth or Bishop Harmon forceps to hold this tissue in place, making a cut on either side using an 11‐blade to subsequently remove this triangular section of tissue. The author recommends starting a minimum of 1–2 mm from the edge of the alar fold, as the wedge can be difficult to close if there is not a substantial amount of tissue to move laterally to close. Hemostasis is obtained using a sterile cotton‐tipped applicator; however, bleeding will persist until the edges are sutured. The author prefers 4‐0 PDS on an RB‐1 needle (the editor prefers 4‐0 Monocryl on a reverse cutting needle) for closure, placing the most distal/ventral suture first, initially holding the edges closed without tying the knot, to ensure adequate patency of the nostril prior to closure. If needed, an additional wedge of tissue can be removed prior to closure. Two to three interrupted sutures are placed to appose the cut surfaces.

Alapexy is a surgical technique used to fix the alae in an abducted position. This technique involves creating two elliptical incisions, one at the ventrolateral aspect of the alar skin and a corresponding incision in the skin lateral to the ala. These paired incised surfaces are then apposed using suture. This technique may be more time‐consuming than other alarplasty techniques due to the need for two incisions and a two‐layer closure.⁴³ It is difficult to make comparisons regarding the effectiveness of different surgical techniques for stenotic nares since most are performed in combination with additional upper airway corrective surgery.

Amputation of the alar skin and underlying cartilage (Trader’s technique) is the first noted corrective surgery for stenotic nares described by Trader in 1949.⁴⁴ This technique may not be favored by some presumably due to hemorrhage associated with the technique, a resulting open wound, and the plethora of other techniques that are available. An advantage of this surgery is the larger amount of tissue that can be removed with the amputation technique compared to alarplasty techniques.⁴⁰ A study revisited the Trader’s technique in immature Shih Tzus documenting the complete resolution of all clinical signs associated with stenotic nares, as well as a cosmetic outcome in all dogs.⁴⁰ The author performs a modified Trader’s technique, utilizing a carbon dioxide laser instead of a blade, preventing the need to control hemorrhage with epinephrine‐soaked gauze strips in the immediate postoperative period. In the author’s opinion, this technique allows the most significant widening of the nares with cosmetic results (Figure 7.5).

Modified Trader’s Technique – Surgical Technique

Safety glasses specific to the laser are required to be worn by all staff within the operating suite if laser is utilized. The patient is placed in sternal recumbency with the chin elevated slightly. The most ventromedial aspect of the alar wing (alar fold) is grasped with rat‐toothed forceps and pulled ventromedially. A sterile cotton‐tipped applicator is placed ventral to the alar fold within the nostril as a barrier to the blade or laser to protect the underlying nasal skin from inadvertent damage. The laser or electrocautery is used to mark the planned region of alar amputation. The proposed line is evaluated and can be adjusted as needed prior to incising. A #11 blade or CO₂ laser is used to excise the alar fold holding the blade or laser at an approximately 40–45° angle from the coronal plane (Figure 7.6; Video 7.2). The same procedure is repeated on the opposite side to make the resulting nares symmetrical. If a blade is utilized, hemostasis is achieved with direct pressure or electrocautery.

Laser‐Assisted Turbinectomy (LATE)

The laser‐assisted turbinectomy (LATE) is an endosurgical procedure developed for the removal of obstructive turbinate tissue to improve endonasal airway patency in brachycephalic dogs.²⁷ CT and anterior and posterior rhinoscopy have identified intranasal anatomical variations in three brachycephalic breeds (Pug, French Bulldog, and English Bulldog).²⁶ Abnormal configuration of the nasal conchal tissue is classified as rostral aberrant turbinates and caudal aberrant turbinates (Figure 7.7).^26,27 Direct intraconchal contact points are responsible for obstruction of the intranasal passageway.²⁶ The surgery results in decreased mucosal contact points in the nasal passages.

The most common complication is transient intraoperative hemorrhage in 32.3% of dogs. Regrowth of turbinates requiring another surgical procedure has been noted in 15.8%.²⁷ Postoperative complications include dyspnea, which may require temporary tracheostomy, especially when laryngeal collapse is present, postoperative regurgitation, and reverse sneezing which is self‐limiting.⁴⁵ At the time of follow‐up, 40% of dogs had intermittent nasal noise when sniffing and excited, which was a different noise than noted preoperatively, and 20% of dogs had a BOAS index that remained >50%.⁴⁵

The outcome of the LATE procedure, performed two to six months after conventional multilevel surgery, was assessed using the median BOAS index based on WBBP. The median BOAS index decreased from 66.7% to 42.3% after LATE.⁴⁵

There can be several disadvantages when considering the LATE procedure. Specialty equipment for diagnostics and treatment (CT, endoscopy, diode laser), advanced training, and additional time are required, especially if being performed as part of a multilevel surgery strategy. The mean surgical time for the LATE procedure is 18 minutes with a range of 7–59 minutes.²⁷ Due to the need for advanced training and specialty equipment required for this technique, it is not described here and can be referenced in Oechtering et al.²⁷