Lecture 24 Flashcards
What are congenital melanosis
- Incidental finding: pig and cattle
- Black spots
- May be present in the meninges and intima of the aorta
- No clinical significance

Congenital melanosis
What is pulmonary calcification
- Occurs in hypercalcaemic states - secondary to hypervitaminosis D
- Common sequela to
- Uraemia from chronic renal failure
- Hyperadrenocorticism
- Pulmonary necrosis
- Calcified lungs fail to collapse when thoracic cavity is opened and have a gritty texture

Uremic pneumopathy: chronic renal failure - dog

Pulmonary ossification
What is needed in normal lungs
- Balanced ratio of volumes of air to capillary blood must be present for normal respiration
- Air and capillary blood must be in close proximity across the alveolar wall
What does a ventilation-perfusion mismatch cause
- Collapsed (atelectasis)
- Overinflated (emphysema)
What is atelectasis
Incomplete distension of alveoli
What causes atelectasis
- Congenital
- Lungs failed to expand with air at birth
- Acquired
- Lung has collapsed after inflation has taken place
- Obstructive
- Compressive
*
- Lung has collapsed after inflation has taken place
What will normally aerated lungs float in
Atelectic pieces of lung will sing in formalin
- If neonatal animals have not breathed at birth
- If older animals have acquired atelectasis
What are the 3 types of Atelectasis
A = normal alveoli
B = obstructive atelectasis
C = compressive atelectasis
What is congenital atelectasia
Lungs failed to expand with air at birth
- Failure of lungs to expand is often because of obstruction with amniotic fluid or meconium
- Also occurs if alveoli fail to stay inflated because of altered qualtiy and quantity of pulmonary surfactant produced by type 2 pneumonocytes and club cells
what are the 2 forms of acquired atelectasis
Compressive atelectasis
- Pressure from outside the lungs
- Space occupying masses in pleural cavity
- Transfered pressure
- Bloat
- Hydrothorax, haemothorax, chylothorax, pyothoras
- Loss of negative pressure becuase of pneumothorax, diaphragmatic hernia
Obstructive atelectasis
- Obstruction of airways within lungs
- Reduction in airway diameter
- Mucosal oedema or inflammation
- Blockage of airways
- Mucus plugs, exudate, aspirated foregin material, lung worm
- Occurs when large animals are recumbent for long periods of time
- Due to a combination of mucus not being drained from bronchioles and alveoli, blood-flow imbalances, shallow breathing, inadequate surfactant
What is the appearance of atelectasis
- Depressed below the adjacent surfact of normal lung
- Dark blue/red in colour
- Multifocally distributed
- Lobular

Congenital atelectasis: neonatal calf

Aquired atelectasis: compressive
Dog with hydrothorax

Acquired atelectasis: obstructive
Pig with pneumonia

Diaphragmatic hernia in a cat
What is Pulmonary Emphysema
- Excessive air in the pulmonary system
- Alveolar or interstitial
- Always secondary to obstruction of outflow of air or agonal at slaughter
- Frequently secondary to bronchopneuonia where exudate partly blocks bronchi and bronchioles
- Can be classified as alveolar or interstitial
What is alveolar pulmonary emphysema
Distention and rupture of alveolar walls forming variable sized air bubbles
Exacerbrated by chronic coughing
What is intestinal pulmonary emphysema
- Air bubbles in interstitial tissues
- Mainly occurs in cattle because of lack of collateral ventilation and wide interlobular septa

Bovine Interstitial Emphysema

Bovine Interstitial Emphysema

Bovie Interstitial Emphysema















