Failure of the lung tissue to expand at birth (primary).
Define lung collapse.
Collapse of lung tissue that was previously expanded (ventilated). Also known as secondary or "acquired" atelectasis.
An excessive amount of air within the lungs. In severe cases, the lungs fail to deflate and there are imprints of the ribs on the pleural surface of the lung.
What are some circulatory disturbances that affect the respiratory tract?
What is lung collapse AKA secondary atelectasis usually secondary to?
Name some non-inflammatory disease affecting the respiratory tract.
What is the normal color of the ventilated lung?
What are some common causes of secondary atelectasis?
Pulmonary or mediastinal masses
Prolonged recumbency in large animals
Prolonged abdominal distension in large animals
What are the three types of emphysema?
Describe alveolar emphysema.
Permanent abnormal enlargement of airspaces distal to the terminal bronchioles with destruction of alveolar walls by neutrophil elastase. Good example of this is RAO.
Describe interstitial emphysema.
Septal (interstitial) lymphatics are dilated with air secondary to forced expiration. Good example of this is pneumonia in cattle.
Describe compensatory emphysema.
Area of emphysema is adjacent to an area of consolidation (all species).
What are different kinds of pigmentation that can be seen in the lungs?
-Melanosis: deposition of melanin in alveolar walls (calves, pigs, and lambs)
-Anthracosis: accumulation of carbon in alveolar macrophages (urban dogs and cats); generally harmless
Increased blood flow into tissue.
Decreased blood flow from tissue.
Define pulmonary edema.
Flooding of alveoli by fluid that can mix with surfactant to form a foam which compromises ventilation.
How can pulmonary edema develop?
-Cardiogenic (pressure overload)
-Neurogenic (pressure overload)
-Excessive fluid therapy (volume overload)
-Damage to endothelium or epithelium (by toxic substances, or as part of acute inflammatory process)
When is hemorrhage in the lungs seen?
-Very severe congestion
-Part of severe acute inflammation
Are pulmonary thrombi/emboli/infarction common?
No, they're rare.
What are some predisposing factors to pulmonary thrombi/emboli/infarction?
-Disseminated intravascular coagulation
-Liver abscessation (esp. cattle)
-Endocarditis (all species)
-Lung lobe torsion may cause abrupt infarction (random even in an animal)
Inflammation of the nasal cavity.
Inflammation of the lining of the sinus cavities.
Inflammation of the lung.
What are the main types of pneumonia?
Bronchopneumonia (suppurative and fibrinous)
What is bronchopneumonia usually associated with?
What is the distribution of lesions in bronchopneumonia?
Cranio-ventral, due to the increased deposition of infectious agents under gravity.
How is the inflammation spread in bronchopneumonia?
Spread of inflammation is usually by extension from lobule to lobule along the airways, or by necrosis of alveoli and septa in the case of toxin-producing bacteria.
What are some sequelae of bronchopneumonia?
-Resolution: mild inflammation resolves in 7 days, and the lung is back to normal in 3 weeks.
-Deterioration: abscess formation with pyogenic bacteria, pleuritis in severe fibrinous pneumonia with adhesions, or death in fulminating cases due to hypoxemia and toxemia (with or without necrosis)
-Persistence: more severe inflammation becomes chronic with fibrosis or bronchiectasis.
What is bronchiectasis?
Permanent dilation of some bronchi due to irreversible damage to the bronchial wall. It is the sequel to chronic bronchitis or persistent bronchopneumonia.
In what species is bronchiectasis principally seen?
Cattle (but can also be seen in pigs, goats, and sheep).
What is lobar pneumonia?
-An aggressive fulminating bronchopneumonia.
-Results from invasion of a highly toxic bacterium (for example, some strains of Pasteurella).
-Also seen in aspiration of foreign fluids or gastric contents.
What is the sequelae of lobar pneumonia?
-Fibrosis of affected areas in surviving animals.
What is bronchointerstitial pneumonia?
-Occurs as a result of inhaled mycoplasmas and some viruses.
-Initial inflammatory reaction occurs in the bronchioles; main expression is an interstitial lymphocytic proliferation often to the extent of forming complete lymphoid follicles around the airways.
-Lymphoid follicles are a cell-mediated response to chronic persistent antigenic challenge.
What is the importance of bronchointerstitial pneumonia?
Mostly economic; leads to reduced growth rates and a predisposition to the entry of more pathogenic agents.
What is interstitial pneumonia?
-Secondary to hematogenous spread RATHER THAN inhaled damage; affects the entire lung lobe so the distribution is diffuse rather than cranio-ventral (dorso-caudal may be more affected.
-Inflammation is centered on interstitial septa rather than the airway.
What is the etiology of acute interstitial pneumonia?
1. Infections (distemper in dogs)
2. Inhaled chemicals (smoke)
3. Ingested toxins (paraquat or tryptophan)
4. Endogenous conditions (uremia)
5. Hypersensitivity reactions (lungworm infestation)
What is the etiology of chronic interstitial pneumonia?
1. Infections (jaagsiekte in sheep)
2. Inhaled dusts (coal or silica dust)
3. Hypersensitivity reactions (Micropolyspora faeni)
What is paraquat? What effect does it have on the animal?
It is a pneumotoxin that selectively damages the alveolar epithelium. It allows the exudation of fluid in the alveolar lumen with consequent loss of respiratory function.
What is fog fever? What species does it primarily affect?
-Acute bovine pulmonary edema and emphysema caused by excess tryptophan ingestion on lush pasture.
-Primarily affects cattle.
What is the pathogenesis and pathology of fog fever?
-Excess tryptophan in autumn grass is metabolised in the rumen to 3-methyl indole, which is toxic to Type 1 pneumocytes.
-Lungs are enlarged and wet with markedly widened interlobular septa (edema and emphysema); flooding of alveoli with protein-rich fluid
What is embolic pneumonia?
Pulmonary abscesses resulting from septic emboli in pulmonary vessels; it is usually secondary to endocarditis or hepatic abscessation and phlebitis.
What is granulomatous pneumonia?
It is pneumonia that is caused by agents such as mycobacteria and fungi (tuberculosis, aspergillosis, etc). Inflammation is chronic and persistent, with macrophages the predominant cell type involved.
Describe nasal and nasopharyngeal polyps.
They can be single or multiple sessile or pendunculated asses secondary to chronic irritation/inflammation. Composed of hyperplastic to ulcerated epithelium, granulating to fibrous stroma and varying numbers of inflammatory cells.
What is hypertrophic pulmonary osteopathy?
Also known as Marie's disease; it is the periosteal thickening of long bones secondary to chronic lung (or heart) disease.