Lasering in on a better approach to BOAS

Vetmed is much better equipped now to address the surgical needs of brachycephalic obstructive airway syndrome

Brachycephalic dog breeds have increased in popularity over the last 15 years while suffering from multiple well-documented health problems.

Despite increased general awareness of their conformation-related problems, their appeal continues to grow. The result is increasing numbers of dogs selectively bred for shorter noses, wider faces, and predisposition to brachycephalic obstructive airway syndrome (BOAS).1

Understanding the pathogenesis of BOAS has increased, along with appreciation for the multiple morbidities that accompany genetic selection for brachycephaly. It was rare to find research or publications about BOAS and the implications for patient welfare before 2005. Since then, more than 110 scientific publications have published advanced knowledge about how to best manage patients affected by BOAS and influence selection in affected breeds.2

The increase in BOAS-related publications from 1985-2020. Photo courtesy Stonehaven Veterinary Consulting
The increase in BOAS-related publications from 1985-2020.
Photo courtesy Stonehaven Veterinary Consulting

These developments have been accompanied by increased use of CO2 surgical lasers in small animal practices. Practitioners have become adept at using surgical lasers to facilitate correction of obstructive airway abnormalities. This has increased the frequency of surgical intervention for BOAS patients at earlier ages. Early correction of airway obstruction is now more common and helps predisposed patients avoid the complications of BOAS.3 Although this paradigm shift has improved the quality of life of many brachycephalic dogs, the overall welfare of brachycephalic breeds remains challenging.

What we have learned

Brachycephalic conformation includes multiple anatomical abnormalities. Stenotic nares, aberrant turbinates, elongation of the soft palate, and tracheal hypoplasia are the physical abnormalities restricted airflow. Greater pressures are required during breathing, particularly during inspiration. Over time, increased negative pressure in the airways results in secondary changes, including pharyngeal hyperplasia, eversion of the laryngeal saccules, hyperplasia of the tonsils, and laryngeal and bronchial collapse.

As changes compound, BOAS symptoms become more evident. The charming, gentle snoring of the brachycephalic dog is replaced by gagging, regurgitation, stridor, reduced exercise tolerance, and dyspnea. Episodes of hyperthermia and syncope may be seen in later stages.4

BOAS is a progressive syndrome with secondary pathologies following inherited anatomical abnormalities. If untreated, prognosis becomes progressively worse. General practitioners have historically not performed surgeries to correct the anatomical abnormalities, considering the procedures difficult and high risk. Severely affected patients were referred to surgeons after BOAS had significantly hindered the patient’s quality of life.

A look back

Using a CO2 laser to resect the soft palate was first described in 1994 and represented a new option for surgical treatment of palate elongation in dogs.5 The technique was rapid and uncomplicated with good hemostasis. Evaluation of CO2 laser versus conventional incisional techniques for resection of soft palates showed similar clinical outcomes—with the advantage of the laser resection’s simplicity and reduced surgical time.6

The development of laser techniques for soft palate resection, accompanied by the increased use of surgical lasers by general practitioners, facilitated earlier and more frequent surgical intervention at the primary care level. General practitioners using CO2 lasers learned palate resection is a procedure they can perform with confidence and good prognosis. They also discovered the laser gives them a valuable, additional tool when correcting nares stenosis. Using several different surgical approaches, stenotic nares can be laser-corrected with minimal hemorrhage and postoperative complications.

When general practitioners became proficient and confident with BOAS procedures, early intervention became widespread. The knowledge that early intervention is the best way to prevent BOAS complications has been well established.7,8,9 The CO2 laser made application of that knowledge possible for nonspecialists.

Young patients with severe nares stenosis are candidates for surgery as early as three to four months old. Less severe patients should have the stenosis corrected by six months of age.10 Regardless of the age of stenosis repair, the palate should be evaluated and elongation corrected at the same time.

Eversion of the laryngeal saccules and tonsil hyperplasia may develop in older patients with complicated BOAS. Early correction of the stenotic nares and soft palate elongation prevent these secondary changes. Most surgeons agree excision of everted saccules is necessary only in older patients with more severe, progressive BOAS.11 Some reports indicate tonsillar hyperplasia resolves when stenotic nares and elongated soft palates are corrected.12,13 Other authors recommend tonsillectomy if there is sufficient tonsillar hyperplasia to create obstruction within the pharyngeal area.10

New concepts for CO2 laser BOAS surgery

The early premise of using the CO2 laser for correcting conformation defects of brachycephalic dogs was straightforward: perform the conventional surgical procedures while substituting the laser for scalpel and scissors when cutting affected tissue. The techniques for this simple transition to using the laser with both stenotic nares and elongated soft palate corrections have been widely published with pictorial instructions.10,14,15,16,17

Pre-op evaluation: Practitioners should establish a minimum database of examination information when assessing brachycephalic patients. Initial consultation with the owner should include the patient’s familial history, lifestyle, behavior, and symptoms in the home environment, as well as an assessment of the client’s knowledge and awareness of BOAS. A complete physical examination should include evaluating potential comorbidities in the musculoskeletal system, eyes, dentition, and skin.

Patient positioned in ventral recumbency with mouth secured open for soft palate resection.
Patient positioned in ventral recumbency with mouth secured open for soft palate resection.

Assessment of the degree of brachycephalic abnormalities should include evaluation of respiratory noise pre- and postexercise,18 scoring of nares stenosis,19 and craniofacial ratio.1 If possible, the intranasal airway should be examined for aberrant turbinates20 and mucosal contact points.21

New evidence recommends practitioners assess preoperative brachycephalic risk (BRisk) to assist triage, make decisions about intervention, and manage owner expectations. A suggested 10-point BRisk score includes consideration of breed, history of previous surgery, concurrent procedures, body condition score (BCS), airway status, and rectal temperature to measure risk of major postoperative complications.22

Laser surgical technique: Using the CO2 laser for BOAS surgeries requires application of up-to-date techniques. Recommendations for best laser-tissue interaction have changed since lasers were first used by veterinary surgeons. CO2 surgical lasers are now more powerful, have more sophisticated settings, and are equipped with more efficient and ergonomic delivery systems. Understanding how to combine multiple laser parameters to achieve the best tissue effect is critical to maximizing BOAS surgical outcomes.

Just as with conventional BOAS surgeries, cutting with a sharp “laser knife” is indicated. Current protocols include use of higher-power levels and a smaller spot size than recommended in initial descriptions of BOAS surgeries. The use of pulsed delivery facilitates nontraumatic marking of tissue prior to incision. Superpulsed delivery during incision helps reduce thermal damage to the tissue left behind. When incising the nares or the soft palate, placing the tissue under tension shortens the time of surgery and helps reduce tissue damage. The best tissue effect results from exposing tissue to laser energy for the shortest amount of time.23

Stenotic nares repair: Two different procedures have been described for stenotic nares correction. The first duplicates the conventional alar fold wedge excision, followed by closing the defect with sutures. The advantages of using the CO2 laser in this surgery are minimal hemorrhage and excellent visualization, allowing bilaterally symmetrical removal of tissue and enhanced postoperative cosmesis.16

An alternative technique is completely excising the portion of the alar fold obstructing the medial meatus. In this technique using a low-power pulsed delivery, the initial lines of incisions are laser marked for bilateral symmetry. Excision of the impinging alar folds must extend deeply enough into the nasal cavity to remove all the obstruction. If remnants of the fold remain after the initial excision, they can be removed by using the laser to ablate the remaining alar cartilage. The advantage of this technique is that it requires no sutures, no suture removal, and as with a wedge excision, results in minimal hemorrhage, excellent intraoperative visualization, and good cosmesis.10

Soft palate resection: Determining the amount of tissue to excise is critical to successful soft palate resection. I recommend prospective BOAS surgeons become familiar with normal pharyngeal anatomy to better asses what is abnormal. This is easily accomplished by visualizing the anatomy of several dozen normal patients under anesthesia. Pharyngeal anatomy should be assessed prior to intubation with the tongue pressed down but not retracted rostrally.

In normal dogs, the tip of the epiglottis brushes the caudal border of the soft palate on inspiration and expiration. A light articulation of the epiglottis and soft palate is the goal when resecting a redundant soft palate in BOAS dogs. Another important anatomical landmark is an imaginary line between the caudal poles of the tonsils; any soft palate that extends caudal to that line is redundant.24

With the patient in ventral recumbency and the mouth secured open, the initial step in soft palate resection is marking the line of excision. This is easily accomplished by briefly removing the endotracheal tube, pulling the epiglottis rostrally so it lies on the soft palate, and then using the laser in a pulsed mode to mark the outline of the epiglottis. If the soft palate is resected along the marked line, the epiglottis and soft palate will have an anatomically correct articulation.10

Full thickness resection of redundant soft palate is made with moist gauze sponges caudal to the soft palate to avoid damage to other pharyngeal tissue and the endotracheal tube. Gentle ventral traction of the soft palate is required. An initial partial thickness incision along the marked line is followed by complete resection from each lateral side to the midline. In most patients there is no hemorrhage and sutures are not required.10,17

Postoperative complications and management: The assessment of a preoperative BRisk score is important in planning postoperative management. Most BOAS patients should be closely monitored by an experienced veterinarian or veterinary nurse for a minimum of 24 hours following surgery. Complications, which are more common in older patients with advanced BOAS,25 can include dyspnea (managed with supplemental oxygen alone, anesthesia and reintubation, or temporary tracheostomy), aspiration pneumonia, and respiratory, or cardiac arrest. The increased risk of complications in senior patients drives continued consideration of early-age surgical intervention in dogs predisposed to or symptomatic of BOAS. After the stenotic nares and elongated soft palate are corrected, future anesthetic risk is significantly reduced.26

We are all part of the BOAS problem

The growing popularity of brachycephalic dog breeds is an animal welfare challenge, one that we created. Studies show the distinctive physical appearance of brachycephalic dog faces are part of our initial attraction to them. Their large eyes and foreheads, as well as wide cheeks, evoke human responses like the infantile facial stimuli human babies evoke. Their baby-like facial features stimulate positive emotions and nurturing responses in us.27,28 We are instinctively attracted to them by their cuteness. The cuter the breed, the more popular it becomes. The more popular the breed becomes, the more breeders select for traits that make the breed popular.

Unfortunately, a common psychological component of brachycephalic ownership is a dissonance in owners’ perception of their dogs’ health. Owners often do not recognize symptoms associated with BOAS or they assume the symptoms are normal for the breed. Symptoms are commonly ignored until after airway obstruction results in secondary anatomical and physiological changes.1

The solution is our responsibility

The solution to BOAS being a patient welfare challenge is not in surgically correcting conformational defects and performing life-saving surgeries. It is changing perceptions on multiple fronts about the health of brachycephalic dogs. This requires slow, persistent, one-on-one education of clients and breeders, and action through veterinary organizations.

Obligation to owners and breeders: Historically, veterinarians have assumed a passive role in the welfare challenge presented by brachycephalic conformation. Not addressing the predisposition for BOAS with owners and breeders contributes to the problem, as does failing to educate owners about symptoms and disease progression. Remaining passive about the suffering of brachycephalic dogs contributes to the problem.

Veterinarians have the opportunity and responsibility to advise clients and breeders about breed-related health and welfare issues. Clients need evidenced-based information, provided in sensitive and open communication. Breed-related BOAS problems are ideally discussed with owners prior to their purchase of a brachycephalic dog. However, since most clients purchase their pets before the first veterinary visit, this discussion won’t occur until they’ve already selected the dog.

Obligation to get associations on board: Veterinarians must also seize the initiative to influence association and public policy to help breed standards evolve to more normal conformation through official veterinary association position statements. Association members can initiate, help develop, and disseminate responsible position statements. They can also lobby for strengthened animal welfare legislation. Veterinarians can also help by supporting breeders and breed associations actively trying to improve the health and welfare of brachycephalic dogs.

Reversing centuries of phenotype selection for brachycephaly cannot be accomplished quickly. Centuries of breeding selection may even be irreversible in some brachycephalic breeds.4 Regardless, veterinarians have a professional and moral responsibility to join the effort and help correct the problem.

Conclusion

Veterinary medicine is much better equipped now to address the surgical needs of BOAS patients. Advancement of CO2 laser techniques, better evaluation of brachycephalic patients, and earlier surgical intervention by an increasing number of primary care practitioners have dramatically improved the welfare of brachycephalic dogs. This paradigm shift has resulted in more accessible and improved management of BOAS patients. The next paradigm shift must be toward more active involvement of the veterinary profession in helping predisposed breeds evolve with more normal conformation.

John C. Godbold, Jr., DVM, practiced as a solo companion animal practitioner for 33 years. More than 20 years ago, he developed a special interest in the use of light-based modalities in veterinary medicine and has extensive experience with laser surgery, laser therapy, and digital thermal imaging. Dr. Godbold now works with Stonehaven Veterinary Consulting, generating and delivering educational content for colleagues and assisting equipment manufacturers with the development of new laser and light-based technologies. He has contributed chapters on laser surgery in The Feline Patient and Veterinary Laser Surgery and authored a peer-reviewed publication on laser surgery technique in Clinician’s Brief. Over 10,000 copies of Godbold’s Atlas of CO2 Laser Surgery Procedures have been distributed to colleagues around the world. In high demand as a continuing education speaker, Godbold has led more than 700 laser workshops, wet‐labs, and continuing education meetings throughout North America and beyond.

References

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