Respiratory Pathology - lecture 2

Question 1

what is atelectasis?

Answer 1

incomplete distension/inflation/expansion of alveoli

can affect whole lung, one lobe or a few lobules

Question 2

what do atelectatic lungs look like?

Answer 2

sunken and darker in colour than normal lung, since alveolar walls are closer together

Question 3

what are the 2 forms of atelectasis?

Answer 3

congenital and acquired

Question 4

how does congenital atelectasis occur?

Answer 4

lungs aren’t inflated with air at birth

Happens because:
* aspiration of amniotic fluid, meconium or squamous epithelial cells ( = causing obstruction)
* surfactant problem –> alveolar septa stuck together

Question 5

how does acquired atelectasis occur?

Answer 5

collapse of lung after inflation has happened

** common in animals**

Question 6

what are the 2 types of acquired atelectasis?

Answer 6

1. compressive = lungs compressed by something outside lungs but within thoracic cavity
2. obstructive = something blocked an airway, preventing airflow –> alveolar collapse

Question 7

what can cause compressive atelectasis?

Answer 7

1. space occupying thoracic masses (ex. tumor, abscess)
2. transferred pressure from outside lung, like in bloat, or thoracic effusions (ex. hydrothorax/fluid, hemothorax/blood, chylothorax/chyle, pyothorax/pis, pneumothorax/air)

Question 8

what can cause obstructive atelectasis?

Answer 8

1. narrow airway lumen
2. edema or inflammation of airway mucosa
3. obstruction by mucus, exudate, parasites (ex. lungworms) or aspirated material

Question 9

what is emphysema? where can it happen?

Answer 9

over-distension/inflation and rupture of alveolar walls, forming air bubbles in the lung tissue/parenchyma

can happen in lung (alveolar emphysema), lung connective tissue (interstitial emphysema)

Question 10

in context of emphysema, what are big, confluent bubbles called?

Answer 10

bullae

Question 11

there are two types of emphysema: primary and secondary. which one occurs in animals?

Answer 11

secondary emphysema, usually as a consequence of a predisposed condition

Question 12

how does secondary emphysema occur in animals?

Answer 12

1. obstruction of airway (where air gets into alveoli but can’t get out … POP! goes the alveoli)
2. agonal change at death (final gasp of animals against closed airways)

Question 13

what does crepitus mean?

Answer 13

crackly feeling lungs due to accumulation of air bubbles

Question 14

what are 5 examples of non-infectious lung diseases involving circulatory disturbances?

Answer 14

1. congestion
2. hemorrhage
3. edema
4. ARDS
5. embolism

Question 15

define pulmonary congestion

Answer 15

accumulation of blood and fluid in the lungs

Question 16

what’s the difference between pulmonary congestion and hyperemia?

Answer 16

hyperemia = acute, active process of increased blood in organ

congestion = passive process, usually caused by heart failure

Question 17

what types of lung hemorrhage can you have?

Answer 17

1. gradual
2. spectacular = sudden hemoptysis and death
3. not real!! post mortem artifact

Question 18

what would you notice in cases of gradual lung hemorrhage?

Answer 18

endothelial damage or clotting problems

ex. DIC, vasculitis, septicemia, coagulopathies

Question 19

define pulmonary edema

Answer 19

accumulation of fluid in the pulmonary interstitium and alveoli

Question 20

is it normal for fluid to leak into the alveolar interstitium from the capillaries?

Answer 20

yes - fluid is removed by lymph system or eaten by intra-alveolar macrophages

Question 21

what are the two main categories of pulmonary edema?

Answer 21

1. cardiogenic or hydrostatic edema
2. permeability or inflammation related edema

Question 22

what leads to cardiogenic edema?

Answer 22

• increased hydrostatic pressure (CHF)
• increased blood volume (iatrogranic or congestion)
• hypoproteinemia
• reduced lymphatic drainage (due to blockage to lymph vessels)

Question 23

what leads to permeability edema?

Answer 23

• general lung inflammation or damage to pneumocytes lining alveoli –> increased vasc permeability

Question 24

what MAJOR clue do you find in post-mortem that indicates pulm edema was likely the cause of death?

Answer 24

froth in the trachea and it’s gotta be extensive froth (because mild lung edema often happens at time of death regardless of cause)

Question 25

what are other lesions in post-mortem that points to pulm edema?

Answer 25

1. lungs don’t collapse when chest is opened
2. prominent interlobular septa
3. lungs are darker, wet and heavier than normal

Question 26

what is ARDS? can you recognize it in post-mortem?

Answer 26

acute respiratory distress syndrome or “shock lung”

this is clinical diagnosis, no post-mortem lesion

Question 27

how can pulmonary embolism cause respiratory disease?

Answer 27

the lung has a huge capillary bed so it is a sticky spot for emboli to lodge

Question 28

what type of emboli can cause pulm embolism?

Answer 28

1. thromboemboli (not common, since usually broken down by fibrinolysis)
2. septic/bacterial emboli (embolic pneumonia or pulm abscess)
3. fat emboli (from bone fractures, more human thing)
4. tumor emboli (common)

Question 29

is pulmonary neoplasia common in domestic animals?

Answer 29

no, although metastatic lung neoplasia is more common than primary lung neoplasia

Question 30

what is hypertrophic osteopathy?

Answer 30

intrathoracic masses can induce periosteal proliferation in distal limb bones