Pathology of the Trachea

Question 1

Tracheal collapse is most common in what breeds of dogs?

Answer 1

Toy and miniature breeds

Question 2

How can radiographs taken at both inspiration and expiration help locate the site of collapse in tracheal collapse?

Answer 2

To determine if the collapse is a collapse of the cervical trachea (inspiration) or thoracic trachea (expiration)

Question 3

List the agents of kennel cough complex. (3)

Answer 3

1. Bordetella bronchiseptica
2. Canine adenovirus 2
3. Canine parainfluenza

Question 4

Which agent of kennel cough is considered most important in most circumstances?

Answer 4

Bordatella bronchiseptica?

Question 5

What process and agents can cause necrosis of bronchial and bronchiolar epithelium? (5)

Answer 5

• Viral infections
• Inhalation of toxic gases
• Toxins that are metabolized by cytochrome P450 in non-ciliated Clara cells
• Hypersensitivity reactions
• Inflammatory reactions to inhaled irritants

Question 6

How do bronchi and bronchioles respond to transient injury or persistent injury?

Answer 6

• Degeneration, necrosis, detachment, exfoliation of epithelium
• Inflammation
• Mitosis of basal and Clara cells
• Cell proliferation
• Cell differentiation and repair
• (chronic injury: increased production of mucus-secreting cells)

Question 7

What lesions can develop if repair is not complete after injury to bronchi and bronchioles?

Answer 7

• Bronchitis
• Tracheitis
• Emphysema
• Atelectasis

Question 8

Define bronchiectasis.

Answer 8

Permanent dilation of bronchi caused by destruction of muscle and elastic tissue

Question 9

What is the pathogenesis of bronchiectasis? (5)

Answer 9

• Bronchus inflammation/infection
• Neutrophil-derived proteases and oxygen radicals damage epithelium and supportive connective tissue
• Weakening of bronchial wall and reduced mucociliary clearance
• Pooling of exudates in bronchial lumen
• Dilation

Question 10

Bronchiectasis can be associated with what types of lung disease? (4)

Answer 10

• Chronic bronchopneumonia (cattle)
• Ciliary dyskinesia (dogs)
• Lung parasites (pigs, sheep, goats)
• Chronic heaves (horses)

Question 11

What are two extracellular bacterial agents that impair activity of cilia?

Answer 11

1. Mycoplasma bovis

2. Mycoplasma gallisepticum

Question 12

Describe a respiratory disease of cats that represents a type I, IgE-mediated, hypersensitivity reaction.

Answer 12

Feline asthma, histamine release from mast cells causes dilation and increased permeability of blood vessels, leads to bronchoconstriction

Question 13

Describe a respiratory disease of horses that represents a type I, IgE-mediated, hypersensitivity reaction.

Answer 13

Heaves

Question 14

What are the causes of feline asthma and heaves, and why do these diseases usually respond favorably to corticosteroids?

Answer 14

• Caused by allergic reactions to environmental allergens
• Corticosteroids work because they help reduce the activity of the immune system (allergies are an immune-mediate response)