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
What is hyperaemia
- Active: increased blood in vessels as part of acute inflammation
What is congestion
- Passive: decreased outflow of venous blood as occurs in congestive heart failure
- Stagnation of blood in vessels leads to oedema and regression of erythrocytes into alveoli
What is pumonary congestion in heart failure
- What is alveolar macrophages phagocytose erythrocytes
- When severe, many macrphages with brown pigment accumulate in bronchoalveolar space
- Lungs have a patchy red and brown apperance
- In chronic caseslungs fail to collapse due to odeam and fibrosis
Acute pulonary congestion - dog
Chronic passive congestion - dog ‘Heart failure cells’ containing haemosiderin
What is hypostatic congestion a result of
- Gravity and poor circulation
- Built up of blood on the lower lung of animals in lateral recumbency for a lonf period
- Seen in cattle and hoses
- May also have hypostatic odema and affected animals are prone to disruped defense system and infection
- Built up of blood on the lower lung of animals in lateral recumbency for a lonf period
What are the causes of pulmonary haemorrhage
- Trauma
- Coagulopathies
- Disseminated intra-vascular coagulation
- Septicaemia
- Rupture of a major pulmonary vessel may occur in association with lung abscess
- Excercise-induced pulmonary haemorrhage in race horses following excerecise
Haemorrhaes - ferret lung
Fatal pulmonary haemorrhage from a lung abscess
Fatalpulmonary haemorrhage from lung abscess
What are the effects of pulmonary oedema
- Hydrostatic oedema
- Mostly left sided heart failure
- Fluid in alveoli
- Iatrogenic fluid overload
- Reduced blood osmotic pressure
- Hypoalbuminaemia secondary to
- Hepatic failure
- Nephrotic syndrome
- Protein losing enteropathy
- Hypoalbuminaemia secondary to
- Inflammatory oedema
- Oedema accompanies many viral infections and inhaled toxicants
- Type 1 pneumoncytes are highly vulnerable to damage
- Oedema accompanies many viral infections and inhaled toxicants
What is pulmonary oedema
- Grossly, lungs are wet and heavy
- Fluid may be present in the plural cavity
- On cut service, the lung parenchyma oozes fluid
- In cattle and pigs, lobular pattern is accentuated due to oedema and dilated lymphatics in the interlobular septia
- Considerable amounts of frothy fluid in the trachea and bronchi
Pulmonary oedema - cow
Pulmonary oedema - pig
Pulmonary oedema -pig
Pulmonary oedema: rat lung
What is pulmonary embolism
- Vast vascular network means the lung catches many emboli
- Most common are thromboemboli, bacterial emboli, fat emboli and tumour emboli
- Sources include valvular endocarditis, hepatic abscess, septic arthritis and omphalitis in farm animlas, fat from bone fractures
- Dirofilaria immitis and angiostrongulus vasorum in dogs
Acute to subacute embolic pneumonia, lung, dog
Jugular thrombophlebitis and pulmonary thromboembolism
Jugular vein and lung: cow
What is pleural effusions
- Hydrothorax
- Heartfailure, hypoproteinaemia, obstructed lymphatics, increased vascular permeability
- Haemothorax
- Trauma, coagulopathies, aortic rupture
- Chylothorax
- Lymph rich in lipids from ruptured thoracic duct
- Pyothorax
- Purulent material: bacterail infections
Haemothorax - dog
Cylothorax
Fibrinous Pleuritis
Pyothorax: nocardiosis
Pyothorax
