SURGICAL DISEASES OF THE UPPER AIRWAY

BRACHYCEPHALIC AIRWAY SYNDROME

The upper airway in dogs consists of the passages that air travels through on its way to the trachea (windpipe) and lungs. This includes the nose, sinuses, pharynx and larynx. There are a variety of problems that can affect the upper airway and compromise the normal flow of air.

The term brachycephalic refers to dogs of a particular short-face conformation (dogs that have a shortened nose and mouth). Bulldogs, Pekinese and Pugs are examples of brachycephalic animals.

A particular set of upper airway abnormalities affect this type of dogs. These problems include stenotic nares, everted laryngeal saccules and an elongated soft palate. These dogs can have any or all of these conditions. Sometimes these problems compromise respiration to such an extent that surgical intervention is required.

SYMPTOMS

Symptoms of brachycephalic airway syndrome often include the following:

		Constant open mouth breathing
		Noisy breathing
		Excessive snoring
		Choking and gagging
		Cyanosis (blue-tinged color)
		Exercise intolerance

Symptoms are often worse during hot and humid weather. Obesity can also worsen the clinical signs.

A diagnosis is made by visual examination of the nares, soft palate and larynx. Laryngeal examinations may need to be performed with the aid of sedation or a light plane of anesthesia.

STENOTIC NARES (closed nostrils)

The nares, or nostrils, of brachycephalic dogs are often to closed to allow for normal respiration. These dogs tend to breathe exclusively through their mouths or make wheezing sounds when breathing with their mouths closed. The treatment of choice for this problem is rhinoplasty (aka, a nose job). To open the nostrils, a small wedge of tissue is resected from the side of the nostril. The remaining tissue is then sutured together, effectively widening the opening of the nares and allowing for more normal respiration.

EVERTED LARYNGEAL SACCULES

The saccules are essentially small bags of tissue that normally sit in a recession just in front of the vocal folds. When we breathe normally, we decrease the pressure in our lung and upper airway by expanding our chests. This action allows air to flow down our airway and into our lungs (just like the way we make liquid travel up a straw). Dogs with compromised airflow through the upper airway must work harder to fill their lungs with air. This decreases the pressure in the upper airway even more and literally pulls the saccules into the airway (just like the way a straw will collapse if you suck hard enough). When everted, the saccules sit just in front of the opening to the trachea and block the flow of air. The treatment for this problem is excision of the saccule tissue.

ELONGATED SOFT PALATE

Just as the name implies, the soft palate in brachycephalic dogs can be too long for the length of the mouth. If it is slightly too long, the clinical signs generally consist of snoring as the free end flaps during respiration. If the palate is even longer, it will hang down into the airway just in front of the opening to the trachea (windpipe) and prevent air from flowing normally. Of the three conditions affecting the upper airway of brachycephalic dogs, this is probably the most serious as airflow can be completely obstructed. The treatment for this condition is to surgically excise the excess palatine tissue. The procedure shortens the palate and prevents interference wit the flow of air.

COLLAPSING TRACHEA

The trachea (windpipe) is a rigid structure composed of numerous cartilaginous rings. In some small breed dogs, particularly the miniature breeds, the cartilage of the trachea degenerates over time. When this occurs, the trachea becomes soft and flaccid, and is prone to collapse during respiration.

The portion of the trachea that collapses may be either cervical (in the neck) or thoracic (in the chest). The most common symptom of collapsing trachea is a chronic, dry, hacking (honking) cough. Severe cases may exhibit exercise intolerance, cyanosis, asphyxia and death. Clinical signs are often worse in hot and humid weather, and are exacerbated by obesity and concurrent airway problems.

The dynamics of respiration describe previously also apply to collapsing trachea. On inspiration, the cervical trachea collapses. On expiration, the trachea in the chest collapses. It is therefore critical to diagnose not only the collapse of the trachea, but also its location.

A tentative diagnosis of collapsing trachea is made based on history and the physical examination. A cough may be elicited on palpation of the trachea. Radiographs (x-rays) may demonstrate the collapse. A definitive diagnosis may require the use of fluoroscopy, an x-ray technique which utilizes a television screen and allows the doctor to see the trachea as the patient breathes. This modality allows the real time visualization of the trachea during inspiration and expiration.

Only the most severe cases are treated surgically. Most respond to correction of the other problems noted here or with medications. Weight loss and correction of concurrent airway disorders may alleviate a significant portion of the problem. Cough suppressants and anti-inflammatory medications (corticosteroids) are often beneficial, as is avoidance of stress and environmental irritants.

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