The French bulldog became the most popular breed of dog in the U.S. in 2022,1 surpassing the Labrador retriever. Unfortunately, the poor choice of breeding of the Frenchie has created a multitude of health problems. Most of these patients present to the general practitioner after six months of age with problems including dyspnea, exercise intolerance, insomnia (obstructive sleep apnea), as well as what are referred to as aerodigestive disorders,2 many of which are dynamic in nature. The typical breeds that present with the abovementioned problems include the English bulldog, French bulldog, and the pug, though this is not an exhaustive list. Pet owner questions should include exercise intolerance, oral or nasal regurgitation, insomnia, shortness of breath, and coughing. Coughing patients should be suspected of having gastroesophageal reflux disease (GERD) and may have nasal discharge, repetitive swallowing, and regurgitation.3 These patients may present clinically with severe respiratory distress, hypoxia, cyanosis, increased abdominal breathing efforts, and recumbency. They should be initially stabilized with cooling, oxygen, NSAIDs, sedation, and IV fluids prior to diagnostic evaluation, as the stress may lead to further decompensation. Some of these patients may be in hypoxic drive, in which the stimulus to breathe is low oxygen tension and not carbon dioxide. A temporary palatopexy4 is an option for those patients that are compromised to the point of severe respiratory distress, a simple procedure that can be performed in general practice. Diagnostics Diagnostics are important to appropriately evaluate the patient. Initial evaluation should include CBC and biochemical profile, VD and lateral chest X-rays to include the larynx to assess the soft palate, heart, and lungs. Appropriately taken radiographs can demonstrate elongation and, possibly, hypertrophy of the soft palate, enlargement of the heart, aspiration pneumonia, and gastroesophageal hernias. A tracheal diameter to thoracic inlet ratio of less than 0.12 is consistent with tracheal hypoplasia,5 necessitating a significantly downsized endotracheal tube, though this may contribute minimally to increased breathing work. In some patients, the left mainstem bronchus is collapsed.3,12 Gastroesophageal hernias are present in up to 44 percent of patients.6 The cephalic index (CI) is used to determine if a dog is a true brachycephalic.7 The width of the head relative to its length determines the value; thus, a shorter nose yields a higher CI. Much attention has been given to the craniofacial ratio (CFR) and its predictive value for determining brachycephalic obstructive airway syndrome (BOAS). CFRs less than 0.5 have shown consistent association with BOAS offspring and are used by some to choose not to breed their dogs.8,9 Stenotic nares are present in 75 percent of BOAS patients.10 Clinically, this is evident by the presence of narrowing of the nares to less than one third the total distance across the nose. Nasolabial flaring is also evident in compromised patients. Flexible endoscopic evaluation of the nares into the nasal cavity may show further increased narrowing by evidence of increased mucosal contact points, limiting the flow of air, and in humans, associated with rhinitis. Stenotic nares and nasal cavity obstruction have been shown to provide 80 percent of the resistance of airflow into the lungs.9 The majority of that obstruction is in the rostral one third of the nasal cavity, suggesting we should focus our efforts there on reducing resistance, with one paper stating that staphylectomy procedures may not be vital to recovery.11 Its effect may be opening of the nasopharyngeal space and not the relief of the rima glottidis. Pugs have no free air dorsal to the soft palate. The patient's larynx can be evaluated visually using light sedation. The soft palate will be significantly long for up to 90 percent of BOAS patients to the point that it covers the epiglottis (Figures 1 and 2). The thickness of the palate can be evaluated by turning it sideways with a skin hook. Thicker palates compromise the dorsal nasopharynx area and make traditional staphylectomy a poor surgical choice, as dorsal displacement of the remaining palate into the nasopharynx may continue. Figure 1. Photo courtesy Dr. Jeff Mayo Figure 2. Photo courtesy Dr. Jeff Mayo The soft palate must be retracted dorsally, and the epiglottis ventrally to assess for everted laryngeal saccule and laryngeal disease. These saccules are in front of the vocal cords, and if significantly hypertrophied, may further obstruct the laryngeal opening (Figure 3). Figure 3. Photo courtesy Dr. Jeff Mayo BOAS patients can easily be evaluated with a flexible endoscope. Current technology has created much smaller endoscopes that do not require a significant investment to purchase or a large tower to run them (Figure 4). Figure 4. Photo courtesy Dr. Jeff Mayo Newer, smaller endoscopes can be used to traverse the entire respiratory tract from the nares to the carina and retroflexed to view the nasopharynx and choanal openings. Findings that may require surgical intervention include significant narrowing of the nasal vestibule and nasal cavity, nasopharyngeal stenosis, elongation and thickening of the soft palate, eversion of the laryngeal saccules, laryngeal collapse, and possibly, laryngeal paralysis. Staging of laryngeal collapse is important but may have no bearing on prognosis. Rhinoscopic views can diagnose and document narrowing of the nasal vestibule and cavity, increase mucosal contact points in the turbinate (Figure 5), and protrusion of aberrant turbinate from the conchae into the nasopharynx from a retroverted endoscopic view (Figure 6). Figure 5. Photo courtesy Dr. Jeff Mayo Figure 6. Photo courtesy Dr. Jeff Mayo These aberrant turbinates may be a normal clinical finding in English bulldogs. The smallest airways are dorsal to the soft palate in pugs and French bulldogs, which can be viewed through the retroflexed endoscope. BOAS patients can be intubated with a smaller endoscope, which can be placed inside the endotracheal tube. Evaluation for GE hernias and esophageal or gastric inflammation should be considered. Hernias can intermittently be diagnosed with plain radiographs, barium contrast, or, if you have a gastroscope, passing it into the stomach, retroflexing it, and bagging the patient. With this maneuver, the stomach will sometimes herniate into the esophagus or beside it. Treatment Surgical treatment should begin at the nose and work caudally. Maxillary nerve blocks should be considered using lidocaine and epinephrine to control pain and hemorrhage. BOAS patients are four times more likely to have postoperative anesthetic issues; thus, lowering the anesthetic requirement is necessary to improve morbidity.12 Rhinoplasty in dogs involves removing any of a number of parts of the nasal or alar fold with radiosurgery or a scalpel to increase the width of the nasal vestibule. Based on the concept of Poiseulle’s law, the flow of air through the nasal cavity is directly proportional to the 4th power of the radius, thus, small increases in the size of the nasal cavity should result in increases in flow. The two best techniques the author uses are the vertical alaplasty or the dorsal offset rhinoplasty. Ala vestibuloplasty may jeopardize the distal openings of the nasolacrimal duct if done incorrectly. The tonsils are frequently swollen and prolapse out of their crypts, resulting in a decrease in the radius of the oropharynx. This results in increased respiratory effort, coughing, and drooling. Their consistent removal during BOAS procedures has not been shown to increase clinical outcomes. Eversion of the laryngeal saccules is reported in over 50 percent of BOAS-affected dogs.11 It can lead to increased airway compromise when they obscure the ventral aspect of the rima glottidis, sitting in front of the vocal cords. Their removal has been advocated using scissors, radiosurgery, laser surgery, and other techniques. The immediate area tends to swell after surgical manipulation and tends to worsen postoperative recovery, often requiring 24-hour care. Some surgeons routinely remove them, while others do not unless essential.13 They may grow back or produce scar tissue. Techniques to address the elongated soft palate should be chosen based on the clinical evaluation of the length and width of the palate, as well as the presence of redundant pharyngeal tissue. Traditional staphylectomy procedures only address the length and may be adequate in many cases, while a thickened soft palate (greater than 10 mm) requires a shortening and thinning procedure, such as the folded flap palatoplasty.10 Several of the new techniques advocate more extensive shortening of the palate to the point where you can visualize the oropharyngeal ostium and see the endotracheal tube entering the larynx. Historically, veterinarians were concerned about making the palate too short, resulting in aspiration pneumonia, although nasopharyngeal aspiration seems to be the worst problem. Radiosurgery techniques to shorten the palate have been performed successfully, using various tips (Figure 7), and more recently with a bipolar instrument.14 Vessel sealing devices are frequently utilized due to their apparent ease, but were noted in one study to have significant postoperative complications associated with tissue dehiscence.15 Figure 7. Photo courtesy Dr. Jeff Mayo Carbon dioxide lasers are frequently utilized, but carbonization of the tissue resulting in necrosis, as well as scatter of the beam in the pharynx near oxygen-filled endotracheal tubes, are a concern. Surgical treatment of GE hernias may not be required. Many of the BOAS-related GERD conditions tend to improve or resolve with the correction of BOAS problems.10 More recent evidence suggests GI disturbances should be viewed as a separate problem in the BOAS patient, as they tend to have a larger-than-normal esophageal hiatus.16 Surgically, a GE hernia can be treated with a left-sided gastropexy, hiatal plication, and/or an esophagopexy. The author tends to wait on treating these surgically unless the stomach is obviously in the thorax. Medical treatment for patients with BOAS should be reconsidered with the presence of other conditions that negate surgical intervention, financial constraints, patients that do not respond well to surgical intervention, or lack of access to appropriate skilled surgery. Being able to handle the complications in more advanced cases or referral for 24-hour care is important. Long-term medical therapies to consider include omeprazole (may cause diarrhea), metoclopramide, maropitant, NSAIDs, and avoiding stress or heat. Weight loss is imperative as obesity can further exacerbate the condition by increasing the work of breathing. Those patients that continue to have problems sleeping may have obstructive sleep apnea, which may respond to ondansetron therapy. In summary, BOAS patients can be appropriately assessed in the general practice setting using flexible endoscopy. Surgical procedures to correct respiratory problems are becoming more common in this setting, and with proper preoperative evaluation and patient selection, appropriate corrective techniques can be undertaken in the day practice. It is equally important to be aware of and evaluate the BOAS patient for many of the other problems that may also incur outside of the upper airway, including gastrointestinal, urinary, and ophthalmic conditions. Jeff Mayo, DVM, DABVP C/F, MANZCVSc (Surgery), has been providing mobile surgical and diagnostic procedures in Western Washington for 21 years. His focus has been on orthopedic and soft tissue surgery, radiosurgery, and, recently, flexible endoscopy and surgical ultrasound. Dr. Mayo enjoys continued education, achieving multiple veterinary master’s degrees in the past two years, with time out for hiking with his two favorite dogs.
