Breathe Right
What is the condition that affects dogs with flat faces?
Dogs with short muzzles and flat faces are called “brachycephalic.” The term comes from the Greek words “brachy,” meaning short, and “cephalic,” meaning head. They usually have a rounded head and large eyes. Some of the most popular dog breeds are brachycephalic, including French Bulldogs, Pugs and Boxers. Their appearance and personalities have made them sought-after family pets and show dogs.
The unique smooshed face of the brachycephalic breeds is a result of selectively breeding for shortened skull, facial and nasal bones. This structural shortening of the face also results in anatomical changes to the throat and airways. Brachycephalic obstructive airway syndrome (BOAS) refers to a specific combination of abnormalities affecting a dog’s airway and breathing.
The upper-airway abnormalities that occur in this syndrome include:
Stenotic nares. Dogs with stenotic nares have abnormally narrow nostrils or small nostril openings. The narrowing restricts the amount of air that can flow into the nostrils. This results in a decreased ability to breathe through the nose, which leads to increased panting and a higher risk of overheating.
Extended nasopharyngeal turbinates. Nasopharyngeal turbinates are ridges of bone covered by tissue that help humidify and warm air that is inhaled. When these extend past the nose into the pharynx (the area behind the nose and mouth), they cause variable amounts of airflow obstruction.
Elongated soft palate. The soft palate is the part of the roof of the mouth made up of tissue that separates the nasal passage from the oral cavity. A dog with an elongated soft palate has a soft palate that is too long for the length of the mouth. The excess flaps into the throat, causing snoring sounds and blocking airflow into the windpipe and lungs.
Laryngeal collapse. The larynx, or voice box, can become damaged by chronic stress to the cartilage from working too hard to breathe. Eventually, the larynx is not able to open as wide as normal. Laryngeal collapse leads to more blockage of the airway and trouble breathing.
Everted laryngeal saccules. The laryngeal saccules are small sacs or pouches that are located just inside the larynx. These saccules evert, or turn outward, and are sucked into the airway by pressure associated with the increased respiratory effort caused by stenotic nares and the elongated soft palate. Everted laryngeal saccules will further obstruct airway flow.
Hypoplastic trachea. A hypoplastic trachea means that the trachea has a smaller diameter than normal. This can make it harder for dogs to breathe in enough air with each breath — like breathing through a straw.
A dog with BOAS may be affected by a combination of one or more of these abnormalities.
What are the symptoms of brachycephalic obstructive airway syndrome?
These upper airway abnormalities cause increased airway resistance, which increase the effort required to breathe. Most dogs with this syndrome breathe more easily through their mouths than their noses. The more abnormalities the dog has, the more severe the signs will be.
Mildly affected dogs will have noisy breathing, especially with exercise, and most will snort when excited and snore when relaxed or asleep. Severely affected dogs have louder airway noise, tire easily and may collapse after exercise.
Other signs include coughing, gagging, retching and vomiting. Symptoms are often worse in hot or humid weather. Affected dogs are more prone to overheating, as their ability to lower their body temperature by panting is compromised.
Obese dogs are more likely to be affected than dogs maintained at a healthy weight. Long term, the increased effort associated with breathing can put a severe strain on the heart and lungs.
How can I tell if my dog needs treatment for BOAS?
A three-minute exercise tolerance test has been described that helps classify dogs with BOAS according to a functional grading system. This grading system classifies dogs according to the severity of clinical signs before and after three minutes of trotting on a treadmill at four to five miles per hour (6.4-8 km/h). Respiratory noise, inspiratory effort and the presence of labored breathing, cyanosis (blue gums) or fainting are noted. The classifications are as follows:
Grade 0: Clinically unaffected
Grade I: Mild snorting but no exercise intolerance
Grade II: Moderate clinical signs that require treatment
Grade III: Severe clinical signs that require emergency surgical intervention
What is the treatment for BOAS?
For dogs with mild or intermittent signs, the condition may be managed conservatively by controlling exercise levels, avoiding hot or humid conditions, keeping the dog in an air-conditioned area during hot weather, and avoiding stress.
Corticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs) and oxygen therapy may all be useful for short-term relief of airway inflammation or respiratory distress. However, medical management of this condition does not correct the underlying anatomical abnormalities.
Surgery should be considered if the structural abnormalities cause life-threatening respiratory distress. Life-threatening would be defined as more than one episode where your dog had trouble breathing and required medical assistance. Multiple procedures are usually required to alleviate the signs of brachycephalic obstructive airway disorder.
Stenotic-nares resection is a procedure in which the nostrils are surgically made wider to improve airflow.
Soft-palate resection is the surgical trimming of the soft palate to shorten the excess tissue that blocks the airway.
Laryngeal-saccule removal involves excising the everted saccules.
All three procedures can be performed at the same time, if necessary. The specific surgical procedure will depend on the individual dog’s anatomy and the severity of his breathing problems. Most dogs with BOAS are diagnosed by four years old, but surgical correction can be performed as early as four months of age. Early diagnosis and surgical intervention may help reduce the progression of chronic airway disease, such as developing laryngeal collapse.
Brachycephalic dogs are at increased risk for complications associated with sedation or general anesthesia since recovery may be more difficult due to the narrowed airways. Anesthesia can increase the risk of regurgitation and may promote tissue swelling, which can further worsen breathing during recovery.
Dogs undergoing BOAS surgery are monitored carefully after surgery to watch for inflammation and bleeding. Typically, they will remain hospitalized in a 24-hour ICU facility for one to two days of observation post-surgery. During anesthesia recovery, many brachycephalic patients tolerate an endotracheal tube for prolonged periods, and removing the tube should be delayed for as long as the tube is tolerated. These dogs appreciate having a firm, open airway to breathe through in spite of the irritation of the tube in their throat.
The prognosis after BOAS surgery is good for young dogs, and most owners see a significant improvement in their dog’s breathing and ability to exercise. The prognosis may be more guarded in older dogs with a long history of trouble breathing, especially if they have started to develop laryngeal collapse. In cases of advanced laryngeal collapse, a tube may need to be inserted in the neck to provide improvement in breathing. This procedure is called a permanent tracheostomy.