Trachea

Question 1

Trachea

Answer 1

Attached at the larynx and carina
Surrounded by cartilaginous rings- not complete dorsally
Fibrous CT between each ring
Trachealis muscle- dorsal tracheal membrane
Easiest to evaluate in lateral view
Angles slightly ventrally from spine- deviates, doesnt line up all the way
additional small dip at carina
Throacic trachea normally slightly to right of mediastinum in VD
rightward position exaggerated in obese and brachycephalic breeds
can mistake for mediastinal or heart base mass

Question 2

Radiographic positioning

Answer 2

head and neck position can affect trachea position
in lateral view, neck must remain neutral
extension results in compression and narrowing at thoracic inlet
flexion results in bend in cranial mediastinum= False diagnosis of a cranial mediastinal mass

Question 3

Tracheal problems

Answer 3

Primary: tracheal collapse (common), hypoplasia (common in bulldog), foreign body (uncommon), tumor (uncommon)

Secondary: displacement (common)

Question 4

Tracheal hypoplasia

Answer 4

Apparent hypoplasia can resolve spontaneously with growth

Question 5

Tracheal collapse

Answer 5

Dynamic in nature
Diameter varies with respiratory cycle
Cervical narrowing occurs during inspiration
Thoracic narrowing occurs during expiration
Thus can miss detection in static image
Pomeranian and yorkies= poster dogs

Question 6

Dynamic airway collapse

Answer 6

Inspiration creates negative pressure in pleural space and tracheal lumen. Pleural pressure is more negative than in thoracic trachea, keeping it open. But pressure in neck around cervical trachea is higher than in lumen leading to collapse

Expiration creates positive pressure in pleural space. Pleural pressure is higher than in thoracic trachea causing it to collapse. Air flowing into cervical tracheal lumen creates higher pressure than in neck, keeping it open.

Question 7

Management

Answer 7

Weight loss, 
cough suppressants
Antibiotics
Bronchodilators
Corticosteroids
LAST RESORT- stenting