Pathology of the Lung

Question 1

List major causes of compressive pulmonary atelectasis (6)

Answer 1

1. space-occupying lesions
2. hydrothorax and hemothorax
3. exudative pleuritis
4. mediastinal and lung tumors
5. diaphragmatic hernia
6. abdominal distension

Question 2

List major causes of obstructive pulmonary atelectasis (3)

Answer 2

1. complete airway obstruction
2. complete blockage of lobar and segmental bronchi
3. bronchial obstruction by exudate, parasites, aspirated foreign material, granulomas, and tumors

Question 3

List the cause of congenital pulmonary atelectasis

Answer 3

lungs appear as in fetus

Question 4

List the major causes of pulmonary edema (5)

Answer 4

1. increased venous hydrostatic pressure
2. increased permeability of the alveolar barrier
3. impaired active transport of fluid from distal airways
4. reduced oncotic pressure
5. lymphatic obstruction

Question 5

What is the physiological significance of edema? (4)

Answer 5

1. decreased lung elasticity
2. impaired ventilation (dyspnea)
3. fluid in alveoli obstructs gas exchange
4. proteins in edema fluid can interfere with surfactant production

Question 6

Why is infarction of the lung relatively uncommon?

Answer 6

it is rare because there would need to be obstruction of a large artery and inadequate collateral flow (chance of the two happening together are slim)

Question 7

What is the cause of exercise-induced pulmonary hemorrhage in horses?

Answer 7

elevated pulmonary arterial and capillary pressures during exercise

Question 8

Can epistaxis occur in exercise-induced pulmonary hemorrhage in horses?

Answer 8

yes but it occurs in less than 2.5% of horses

Question 9

Describe the lung appearance in bronchopneumonia and what it would look like on cut surface.

Answer 9

• irregular consolidation and darkening of cranioventral lung
• cut surface: edema fluid and purulent exudates

Question 10

Describe the lung appearance in fibrinous bronchopneumonia.

Answer 10

-cranioventral lesions are covered by fibrin (pleuritis)

Question 11

Describe the lung appearance of interstitial pneumonia and what it would look like on cut surface.

Answer 11

• mild increase in firmness or rubberiness and lungs do not collapse
• pink/grey to red/grey and can have impressions from overlaying ribs
• cut surface: minimal or no exudates released

Question 12

Describe the lung appearance of atelectasis

Answer 12

• collapse of the lung
• affected areas are depressed and red, but not firm
• can involve whole lungs, lobes, or lobules

Question 13

Describe the lung appearance of edema and what it would look like on cut surface.

Answer 13

• distended with fluid and are heavy and slightly firmer than normal
• cut surface: clear or blood-tinged fluid expressed

Question 14

Describe the lung appearance of embolic pneumonia and what it would look like on cut surface.

Answer 14

• multiple widely distributed white to yellow abscesses (hematogenous origin)
• cut surface: abscesses contain white pasty to viscous fluid

Question 15

Describe the lung appearance of granulomatous pneumonia.

Answer 15

-multifocal granulomas that are caseous or noncaseous

Question 16

What is the definition of interstitial pneumonia?

Answer 16

damage to or inflammation of the alveolar septa and interlobular septa

Question 17

Give examples of agents that cause interstitial pneumonia. (5)

Answer 17

1. viruses
2. some bacteria (salmonella)
3. fungi
4. protozoa
5. toxins

Question 18

Give examples of agents that cause embolic pneumonia. (4)

Answer 18

septic emboli

1. endocarditis
2. injection site abscess
3. hepatic abscess with phlebitis of hepatic vein (cattle)
4. infected jugular catheters

Question 19

Give examples of agents that cause granulomatous pneumonia. (4)

Answer 19

1. fungal organisms (Blastomyces dermatitidis)
2. some bacteria (Mycobacterium sp.)
3. aberrant parasites (ascarid larva)
4. foreign bodies

Question 20

What are four categories used to describe the morphology of a lung lesion?

Answer 20

duration
distribution
degree of severity
exudate

Question 21

Why does bronchopneumonia of cattle and swine resolve more slowly than that of other domestic animals?

Answer 21

cattle and swine do not have collateral ventilation of alveoli, thus they have reduced clearance of exudates

Question 22

A calf has bronchopneumonia. In terms of pathogenesis, list at least three possible resolutions or outcomes of the bronchopneumonia.

Answer 22

1. Death - toxemia developed
2. Complete resolution - infection removed by immune response or antibiotics
3. Chronic suppurative bronchopneumonia - persistent infection or secondary bacterial infection

Question 23

What is the pathophysiological significance of bronchopneumonia? (4)

Answer 23

1. loss of functional parenchyma for ventilation
2. decreased elasticity/compliance of lung
3. progress to death, pulmonary fibrosis, septicemia, bronchiectasis
4. chronic bronchopneumonia results in weight loss and progressive loss of lung function

Question 24

What is a lung sequestrum and how long does it persist in the lung?

Answer 24

mass of necrotic tissue that is separated from normal lung by suppurative exudate and fibrous connective tissue

permanent and nonfunctional

Question 25

List common causes of aspiration pneumonia. (7)

Answer 25

1. aspiration of milk by animals with cleft palate, megaesophagus, or persistent right aortic arch
2. aspiration of ruminal contents by downer cow
3. mineral oil force fed to cat as furball treatment
4. aspiration of vomitus by animal recovering from anesthesia
5. accidental tracheal tubing in cow or horse receiving mineral oil
6. aspiration of feed material by tube-fed parrot
7. aspiration of crop fluid by Macaw with proventricular dilatation syndrome