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Tracheal Collapse
From Honking Cough to Complete Airway Obstruction

Anatomy

  • The trachea (aka windpipe) is a tube connecting the larynx (voicebox) with the bronchi (the lower airway, connecting to the lungs)
  • The tube contains a series of incomplete, C-shaped cartilage rings that hold the trachea open to allow air passage

Tracheal Collapse

  • Degenerative and irreversible
  • C-shaped cartilage weakens and collapses progressively
    • Most often collapses so that back and front of trachea touch
    • Cervical (neck) tracheal collapse usually worse during inspiration (breathing in)
    • Thoracic (chest) tracheal collapse usually worse during expiration (breathing out)
  • Focal or diffuse
    • May affect only a limited region of the trachea
    • Some pets may have collapse of the entire length of trachea
    • Region and degree of collapse typically increases with age
    • Some pets have dynamic collapse (see image and animation below)

History

  • Breed
    • Small breeds, especially Yorkshire Terriers, Pomeranians, Miniature or Toy Poodles, and Chihuahuas
  • Age
    • Most commonly middle aged to senior
    • Signs worsen with age
  • Signs
    • Mild/early cases
      • Dry, "honking" cough when the opposite sides of the tracheal lining touch each other
      • Wheezing during inspiration (breathing in)
    • Moderate cases 
      • Increasing frequency and severity of coughing
      • Episodes potentially leading to distress
    • Severe 
      • Minimal excitement or activity leads to severe coughing
      • Pets' mucus membranes (such as non-pigmented gums) turn cyanotic ("blue") during episodes
      • Pet at risk to die from airway obstruction
        • may need to have an endotracheal tube (such as those used in anesthesia) to get oxygen to the lungs
    • Exacerbated by
      • Pressure on the airway
        • Pulling on the leash in a dog wearing a collar
      • Obesity
      • Smoke
      • Allergens
      • Exercise - doesn't worsen the disease, but the associated excitement and heavy breathing may precipitate coughing and/or distress

Dynamic Tracheal Collapse: 
Cervical (neck) trachea collapses during inspiration (breathing in) and expands during expiration (breathing out); thoracic (chest) trachea expands during inspiration (breathing in) and collapses during expiration (breathing out)

video courtesy of Infiniti Medical


Diagnostics/Tests

  • Chest and neck radiographs (x-rays)
    • Sufficient to diagnose a straight-forward collapse
      • Misses out on dynamic and lateral to medial (side-to-side) collapse
  • Fluoroscopy ("moving x-ray")
    • Identifies dynamic collapse
    • Identifies collapse associated with coughing
  • Endoscopy (tracheoscopy/bronchoscopy)
    • Camera images from inside airway
    • Identifies dynamic collapse
    • Identifies lateral to medial collapse
    • Identifies collapse of bronchi (lower airway)
    • Left image (courtesy of ACVS) shows relatively normal airway as the trachea splits into the two mainstem bronchi
    • Right image (courtesy of ACVS) shows severely collapsed airway. The dorsal (top) portion is nearly completely occluding the airway





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  • Bloodwork
    • Used to rule out other systemic disease that may complicate treatment and/or affect prognosis
  • Echocardiogram (Ultrasound/Sonogram of the heart)
    • Evaluates cardiac/heart function for disease that may complicate treatment and/or affect prognosis

Treatments

  • Medical (palliation)
    • Harness
      • Using a chest harness instead of a leash around the neck decreases the pressure on the trachea
    • Cough suppressants
      • Decrease the sensitivity/spasm to irritation/coughing, which can cause further irritation
    • Sedatives
      • Decrease anxiety, rapid breathing, and urge to cough
    • Bronchodilators (aminophylline, theophylline, etc.)
      • Only really work with lower airway (bronchi or the even smaller bronchioles; but, if these are affected, treatment may improve function)  
    • Steroids
      • Corticosteroids such as prednisone, prednisolone, or the extra-short acting Dexamethasone Sodium Phosphate may help in the short term
      • Continued use may exacerbate collapse as well as lower resistance to pneumonia and other infections
    • Antibiotics
    • Acute (sudden) deterioration in function (severity in coughing or other signs) may be caused by a secondary bacterial infection that is often responsive to fluoroquinalone antibiotics, such as enrofloxacin (Baytril), marbofloxacin (Zeniquin), orbafloxacin (Orbac), or ciprofloxacin, though the latter is often less effective in dogs than in people 
  • Corrective
    • Surgical
      • Extraluminal rings - multiple rings placed around the cervical (neck) trachea
      • Generally not placed in the thoracic (chest) trachea, so ineffective for collapse in that region.
    • Non-invasive
      • Intraluminal stent - placed down the tracheal through the mouth. Brief anesthesia, no incision, rapid recovery and response to therapy.

Having treated numerous patients in both fashions, I strongly recommend the intraluminal stents. For more information on intraluminal stents, see here.

For additional information on tracheal collapse (and on surgical/extraluminal stenting), please visit the ACVS article on Tracheal Collapse. Images courtesy of ACVS. 

Video/animation (pending) courtesy of Infiniti Medical