Tracheal Hypoplasia

Some breeds of dogs and cats are predisposed to difficult, obstructive breathing because of the shape of the head, muzzle, and throat. The breeds most commonly affected are brachycephalic dogs; “brachycephalic” literally means short-headed. Typical examples include the English Bulldog, French Bulldog, Pug, Pekingese, and Boston Terrier. These dogs have been selectively bred for short muzzles and noses, and as a result their upper airways and throat structures are often undersized or compressed/flattened (Figure 1). Persian cats also have a brachycephalic conformation.

Figure 1. Side view demonstrating classic brachycephalic conformation.
Figure 2. Oral exam showing an elongated soft palate extending into the larynx.
Figure 3a. Close-up of stenotic nares.

The term Brachycephalic Syndrome describes a combination of elongated soft palate, stenotic nares, and everted laryngeal saccules, which are commonly present in these breeds.

• Elongated soft palate (Figure 2): the soft palate is excessively long, so its tip protrudes into the airway and interferes with airflow into the lungs.
• Stenotic nares (Figure 3a): the nostrils are abnormally narrow and may collapse inward during inspiration, making nasal breathing difficult.
• Everted laryngeal saccules (Figure 4): tissue within the airway just in front of the vocal cords is pulled into the trachea (windpipe), partially blocking airflow.

Some dogs with brachycephalic syndrome may also have a narrowed trachea, laryngeal collapse (collapse of the cartilages that open/close the upper airway), or paralysis of laryngeal cartilages.

Figure 3b. Normal canine nose for comparison.
Figure 4. Oral exam showing everted laryngeal saccules.

Dogs with elongated soft palates typically have a history of noisy breathing, especially on inhalation. Some will retch or gag, particularly while swallowing. Exercise intolerance, cyanosis (blue tongue and gums from inadequate oxygen), and occasional collapse are common—especially after excessive activity, excitement, or exposure to heat and humidity. Obesity worsens these issues. Many dogs with elongated soft palates prefer sleeping on their backs, likely because this position allows the palate to fall away from the larynx. Signs linked to stenotic nares and everted laryngeal saccules are generally similar.

Stenotic nares can usually be recognized on routine physical examination (Figure 3). A definitive diagnosis of an elongated soft palate and everted laryngeal saccules generally requires anesthesia. Brachycephalic breeds often have a thick tongue, making it very difficult to adequately visualize the larynx in an awake dog; attempts to restrain the patient and retract the tongue enough to see the larynx are typically unsuccessful. Under anesthesia, an elongated soft palate extends beyond the tip of the epiglottis (the airway entrance), and in severe cases it extends directly into the laryngeal opening. The palate tip and laryngeal edges are often inflamed (swollen and red). With chronic disease, laryngeal cartilages may lose flexibility and begin to collapse, further narrowing the airway. Everted laryngeal saccules appear as blue-gray soft tissue protrusions into the airway just in front of the vocal folds (Figure 4). Chest radiographs may also be recommended to assess the lower airways and lungs.

Figure 5. Laser resection of an elongated soft palate.

Soft palate problems should be addressed when they cause distress, progressively worsen, or create a life-threatening obstruction. If a pet has gagging, coughing, exercise intolerance, or breathing difficulty, surgical removal of the excess soft palate tissue may be required. Soft palate resection (staphylectomy) can be performed with a scalpel, scissors, or a CO₂ laser (Figure 5). The palate is stretched (Figure 6), and then the extra tissue is trimmed away.

If laryngeal saccules are everted, they may be removed at the same time as the soft palate surgery, or they may be left and allowed to return toward a more normal position. When stenotic nares are present, correcting them improves airflow and is typically performed during the same procedure (Figures 7 and 8).

Figure 6. The soft palate is stretched prior to trimming.
Figure 7. One side of the stenotic nares has been corrected.
Figure 8. Nose appearance immediately after widening of the stenotic nares.

Close monitoring is essential immediately after surgery. Swelling or bleeding can obstruct the airway and make breathing very difficult or impossible. In some cases, a tube must be placed through a neck incision into the trachea (temporary tracheostomy) until throat swelling decreases enough for normal breathing.

Pets are usually monitored in the hospital for at least 24 hours. Coughing and gagging after surgery are common. In long-standing cases where laryngeal cartilages have become rigid, removing the elongated soft palate and saccules may not provide adequate improvement. In such situations, creating a new permanent airway opening into the trachea at the neck (permanent tracheostomy) may be the only option, although this procedure also carries potential complications.

Prognosis is generally good in young animals: breathing typically becomes easier, respiratory distress decreases markedly, and activity levels can improve significantly. Prognosis is less favorable in older animals, especially if laryngeal collapse has already begun. If laryngeal collapse is advanced, prognosis is poor.