Tracheal collapse is a progressive degenerative disorder of the tracheal cartilage, which results in a reduction of the luminal diameter of the trachea. The normal ring-shaped cartilages become C-shaped and flattened. The trachea becomes stretched and floppy, and to varying degrees falls down and obstructs the tracheal lumen.
The normal diameter of the trachea is maintained by rigid hyaline cartilage rings. The loss of tone in the cartilage causes the collapse but it is unknown why exactly this loss in tone occurs. Dogs with tracheal collapse have abnormal cartilage rings that collapse with changes in tracheal pressure. As the trachea collapses, there is irritation and trauma to the trachea itself, which induces coughing and this induces even more collapse and further coughing.
Toy breeds such as Yorkshire terriers, Chihuahuas, Pomeranians, and Poodles are predisposed and clinical signs typically occur when dogs are middle aged (4-8 years). The most common clinical sign is a honking cough that is usually progressive over several months to years. The cough is typically induced with excitement and exertion. Severe tracheal collapse can lead to dyspnea (difficulty breathing) and exercise intolerance – most dogs have mild to moderate collapse.
The diagnosis of tracheal collapse is made by a combination of breed, history and various imaging modalities including radiographs, fluoroscopy and/or bronchoscopy. Typically radiographs (showing the collapsed trachea) are sufficient to make the diagnosis but further imaging such as fluoroscopy and/or bronchoscopy may be needed to further characterize the severity. Bronchoscopy involves visualizing the airway from the inside using a scope with a camera. Fluoroscopy and bronchoscopy are often utilized if surgery is going to be performed.
NORMAL TRACHEAL COLLAPSE
Tracheal collapse is usually managed medically - surgical management is reserved for severe cases. Medical management includes monitoring (often no treatment for mild – moderate cases), cough suppressants, steroids, and weight reduction. Antibiotics are only indicated if there is evidence of bacterial tracheitis. It is also advised that owners use harnesses and avoid neck collars. Surgical management of tracheal collapse involves placement of an intra-luminal stent to permanently keep the tracheal lumen open and prevent collapse, however, this does not come without potential complications including infection, fibrosis/stricture (permanent narrowing of the trachea), and laryngeal paralysis. It is for these reasons that surgery is usually the last resort and reserved for very severe cases. Most dogs with mild to moderate tracheal collapse can live a normal life and do not typically need medication at all.