Tracheal Collapse

The trachea is a tube that connects the larynx (voice box) to the lungs. This tube is made of soft tissue and reinforced by cartilage rings that are spaced along its length. These rings are “C” shaped with an opening at the top covered by tissue and referred to as the dorsal tracheal membrane and/or dorsal trachealis muscle.

Tracheal collapse is a narrowing of the trachea associated with sagging of the tracheal membrane into the lumen of the trachea and/or weakening of the cartilage rings due to a process called chondromalacia. These changes can occur in a focal area of the trachea or involve the whole trachea. The collapse is often a dynamic lesion meaning it only occurs during certain parts of the breathing cycle (e.g., only on inspiration or only in expiration, or during coughing). In more severe cases it may occur during the entire breathing cycle. In addition, collapse can occur in airways below the level of the trachea (e.g., main stem bronchi).

Tracheal malformation is a static change in the shape of the cartilage rings resulting in narrowing of the tracheal lumen. Because it is static, rather than dynamic, the narrowing is persistent through all parts of the breathing cycle. This is most often seen in young to middle-aged Yorkies.

The classic clinical sign is a cough typically brought on by excitement or exercise. Often the cough is described as a “goose honk” but can be variable in sound. Coughing may start with excitement but result in irritation of the trachea or lower airways leading to a cough that occurs during other times of the day as well. In addition, the narrowing of the trachea or lower airways can result in a wheezing sound during breathing or coughing. As the degree of collapse worsens, obstruction of the airway can occur resulting in difficulty breathing. In severe cases, the gum or tongue color may develop a blue hue (called cyanosis) due to decreased oxygenation of the blood.

These conditions are often suspected based on the presenting breed and clinical signs. Definitive diagnosis requires imaging of the trachea using chest/neck radiographs (X-rays), fluoroscopy (live time X-rays), and/or endoscopy. Radiographs are typically taken during both inspiration and expiration as the collapse may occur during either part of the breathing cycle. Fluoroscopy allows visualization of the trachea during normal breathing and after stimulation of cough. Some dogs will only show collapse when they cough. In addition, the location and severity of the collapse may be greater during cough than under normal breathing. Endoscopy is the use of a narrow tube with a camera at the end to directly view the inside of the trachea. This can help determine the degree of collapse, diagnose malformation, and diagnose concurrent diseases of the lower airways such as bronchitis or infection.

Treatment is split into two categories: Medical management and Tracheal stenting.

This is the cornerstone of treatment in most cases of tracheal collapse, particularly when cough is the main or only clinical sign. Coughing results in irritation to the trachea, lower airways, and larynx. This irritation leads to further coughing and the cycle repeats. A major goal of medical management is to break this cycle. This is often accomplished with the use of anti-inflammatory drugs (e.g., prednisone) and cough suppressants (e.g., diphenoxylate, hydrocodone). 

In addition, we want to reduce risk factors for cough or collapse of the trachea. First, we recommend that a collar be replaced with a harness for leash walking to reduce pressure on the trachea. Many dogs with tracheal collapse are overweight. The additional fat in the chest causes the dog to work harder to breathe, particularly when panting. The harder the dog works to breathe, the more collapse of the trachea that occurs. Hence, weight loss is an especially important part of medical management when obesity is present.  Exercise during hot or humid times of the day should also be avoided as the increased panting will exacerbate clinical signs.

Environmental allergens and irritants can also stimulate cough resulting in collapse, irritation, and repeat of the cycle. As much as practical, we recommend removing irritants from the home environment. This includes removing scented candles, plug-ins, incense, perfumes, etc. Not using carpet deodorizers. Removing carpeting if possible. Cleaning AC/heating ducts to remove dust and mold spores. Using a HEPA filter for the AC/heating system. 

As mentioned, excitement can be a major stimulus of the collapse and cough. This can be difficult to avoid on a daily basis. However, if known exciting triggers are expected (e.g., house guests, Christmas party, etc.), medications can be used to reduce anxiety or cause sedation to help prevent a collapse episode.

This is a minimally invasive procedure used for the treatment of tracheal collapse that is refractory to medical management and/or resulting in difficulty breathing. A tracheal stent is a wire mesh tube made of special materials (think of chicken wire rolled into a tube shape) that is placed using a special delivery device passed through the larynx (voice box). It does not require any incisions. When the stent is “deployed” it opens and exerts outward pressure on the tracheal wall to support it and keep it open. Possible complications of stenting include increased coughing, stent migration (movement after placement), infections, stent fracture (breaking), and development of inflammatory masses (granulomas). Due to these complications, stenting is often considered a “salvage procedure” that is used only when medical management fails.