A 5-year-old male intact Yorkshire terrier presented with a few week history of on and off cough. The owners reported that the cough seemed to only occur on and off throughout the day but would be much worse after exercise or when he would get excited when the owners returned home from work. He also seemed to cough occasionally on walks when tugging on the leash. Physical examination did not reveal any abnormalities. The dog was anxious in the room and repeatedly produced a honking cough. A presumptive diagnosis of tracheal collapse was made and chest radiographs were performed to rule out any other abnormalities. The chest radiographs showed the trachea was completely collapsed in the area of the thoracic inlet (region where the neck and chest meet). Bloodwork was performed and revealed no abnormalities. The dog was sent home with instructions to switch to a harness instead of a collar and to monitor for any increase in severity or any signs of dyspnea (difficulty breathing) or exercise intolerance.
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.