Respiratory Pathology Flashcards
Which structure(s) of the respiratory tract are part of the conducting zone?
Nasal cavity, larynx, pharynx, trachea and bronchi
Which structure(s) of the respiratory tract are part of the transitional zone?
Bronchioles
Which structure(s) of the respiratory tract are part of the exchange zone?
Alveoli
What are the 3 routes of invasion into the respiratory tract?
- Aerogenous (airways)
- Haematogenous (blood)
- Transcoelomic (direct)
When considering aerogenous invasion of a pathogen, larger particles are deposited ___, whereas smaller particles are deposited ___
Larger: above the larynx (higher)
Smaller: at the bronchiolar-alveolar junction (lower)
Which types of pathogens are more likely to adhere to and replicate in the upper respiratory tract before spreading?
Bacterial and viral pathogens
Where do haematogenous lesions tend to be located in the respiratory tract?
In the caudal lobes of the lung (however all lobes can be affected)
List 2 ways in which transcoelomic infection can occur
- Infection via the pleura or mediastinum
- Traumatic penetration (from chest wall, diaphragm, or esophagus)
Define epistaxis
Blood in the nasal discharge
Define hemoptysis
Blood in the saliva or sputum
Which two pathologies of the nasal cavities often occur together?
Rhinitis and sinusitis
List an example of a virus that can cause infectious rhinitis in cats
Feline viral rhinotracheitis
List an example of a virus that can cause infectious rhinitis in dogs
Canine distemper
List an example of a virus that can cause infectious rhinitis in cattle
Infectious bovine rhinotracheitis
List an example of a virus that can cause infectious rhinitis in pigs
Swine influenza
List an example of a virus that can cause infectious rhinitis in horses
Equine rhinovirus
List 3 complications that can occur with strangles
- Metastatic abscesses (bastard strangles)
- Guttural pouch empyema
- Purpura hemorrhagica
In which species do nasal polyps commonly occur with chronic rhinitis?
Horses, cats and sheep
Why are inflammatory diseases involving the pharynx, larynx and trachea of clinical importance? (2 reasons)
- They can obstruct airflow
- They can cause aspiration pneumonia
Why are cattle generally susceptible to the development of bronchiectasis?
Due to the combination of the complete lobular septation of their lungs and lack of collateral ventilation
Which bacterial rhinitis infections are NOT secondary to viral infections
- Atrophic rhinitis (pigs)
- Strangles (horses & dogs)
- Mycotic rhinitis (dogs & cats)
What are the 3 pathological characteristics of strangles?
- Suppurative rhinitis
- Pharyngitis
- Lymphadenitis
List 3 developments of chronic bronchitis
- Excess production of mucus (goblet cell hyperplasia)
- Squamous metaplasia
- Bronchiectasis
What characterizes infectious tracheobronchitis?
Persistent tracheobronchial inflammation
List 2 ways in which bronchiolitis can occur
- As an extension of bronchitis or concurrently with bronchitis and pneumonia
- As a distinct entity
Which pneumocytes are the most susceptible to injury
Type I
Define
Bronchiesctasis
Permanent saccular or cylindrical dilation of bronchi as a result of the accumulation of exudate within the lumen and partial rupture of bronchial walls
Explain the term alveolar epithelialisation
In severe forms of alveolar injury, repair will begin because of type II pneumocyte division. This process looks like a gland, and is thus called epithelialisation.
Another term for this is hyaline membranes
Define
Consolidation
Altered texture of the lung due to accumulation of exudates
List the 6 classifications of pneumonia
- Suppurative bronchopneumonia
- Fibrinous bronchopneumonia
- Bronchointerstitial
- Interstitial
- Granulomatous
- Embolic
Which classification of pneumonia is spread haematogenously only?
Embolic pneumonia
List the cellular characteristics of suppurative bronchopneumonia
Neutrophils, cell debris and macrophages
Where is inflammation focused in bronchopneumonia?
The bronchi, bronchioles and alveolar lumens
What are the 2 consequences of suppurative bronchopneumonia?
- Resolution (3-4 weeks)
- Progression to chronic
How does fibrinous bronchopneumonia differ from suppurative?
It is generally more severe, and involves the entire lobes and pleural surface
Bc it’s more severe, it’s more likely to result in fibrosis & adhesions
Where is inflammation focused in interstitial pneumonia?
Alveolar walls
What are the two phases interstitial pneumonia?
Describe each phase
- Exudative phase (protein & fluid exudation)
- Proliferative phase (type II pneumocytes replace damaged type I cells, aka hylaine membrane formation)
List 2 examples of interstitial pneumonia
- Fog fever (cattle)
- Paraquat poisioning (dogs & cats)
List the cellular characteristics of granulomatous pneumonia
Dominated by macrophages, either lots or no giant cells, and varying amounts of lymphocytes and neutrophils
What is the most common cause of bronchointerstitial pneumonia
Viruses that damaged the airway and alveolar epithelial cells
Describe the disease development of fog fever
When cows are moved to lush pasture in the autumn, they eat more tryptophan, which is metabolized in the rumn to generate free radicals and causes the necrosis of type I pneumocytes
List 4 events that can lead to post-mortem pulmonary abscesses
- Septic emboli
- Extension of severe suppurative bronchopneumonia
- Aspiration
- Direct penetration
Describe the species affected and the condition caused by the pathogen
Parainfluenza virus type 3
Canine
Replicates in the airway epithelial cells and causes bronchiolitis in the alveoli
Describe the species affected and the condition caused by the pathogen
Canine distemper virus (CDV)
Canine
Causes catharral oculonasal discharge, pharyngitis and bronchitis
Describe the species affected and the condition caused by the pathogen
Equine influenza & equine viral rhinopneumonitis
Equine
Mild bronchointerstitial pneumonia
Describe the species affected and the condition caused by the pathogen
Rhodococcus equi
Equine
Causes severe suppurative bronchopneumonia and abscess formation
It lives in macrophages
Describe the species affected and the condition caused by the pathogen
Pasteurellosis
Bovine
Causes shipping/transit fever, and manifests as acute septicaemia
Specifically p. multocida p. haemolytica
How does pasteurellosis manifest in pigs and sheep?
As extensive fibrinous bronchointerstitial pneumonia
Describe the species affected and the condition caused by the pathogen
Respiratory syncytial virus
Bovine
Causes cranioventral atelectasis, consolidation and interstitial emphysema in caudal lung lobes
Describe the species affected and the condition caused by the pathogen
Maedia visna virus
Ovine
Causes lymphoid interstitial pneumonia and smooth muscle hyperplasia
The lungs fail to collapse properly so they can weigh 2x more
Which animals are most affected by enzootic pneumonia
Calves, lambs and pigs (particularly young animals in close contact)
In which animal is enzootic pneumonia synonymous with mycoplasma pneumonia?
Pigs
Which pathogen is known to cause pulmonary mycoses in birds
Aspergillus fumigatus
List the 2 dictyocaulus spp. which affect cattle and sheep (ruminants)
D. viviparus and D. filaria
Describes the phases of pathogenesis of D. viviparus
- Penetration (larvae are in transit)
- Prepatent phase (larvae appear in alveoli, cause bronchitis, and inflammatory cells plug the airways)
- Patent (parasitic bronchitis and pneumonia are seen because of a large number of worms and aspiration of the eggs)
Describe the gross lesion of dictyocaulus infection
Wedge shaped areas of red/grey consolidation
Which animals is M. capillaris infection common?
Sheep and goats
What condition is caused by M. capillaris infection?
Multifocal interstitial pneumonia
Where in the respiratory tract will you find cat lungworm (a. abstrusus)?
In the bronchioles and alveolar ducts
Which parasitic infection causes right sided heart failure in dogs and foxes?
Angiostrongylus vasorum
List 2 examples of type I hypersensitivty disease
- Feline asthma/allergic bronchitis
- Pulmonary infiltration with eosinophils
List 3 examples of type III hypersensitivity disease
- Extrinsic allergic alveolitis
- Diffuse fibrosing alveolitis
- COPD
Which hypersensitivity disease is commonly seen in cattle housedindoor in the winter?
Extrinsic allergic alveolitis (type III)
The combination of which diseases can progress to diffuse fibrosing alveolitis?
- Extrinsic allergic alveolitis
- Fog fever
- Severe alveolar damage
What are the two possible progressions of aspiration pneumonia?
Severe necrotising pneumonia and gangrenous pneumonia
List 2 possible causes of gangrenous pneumonia
- Administration of medications meant for the oesophagus
- Sequel to aspiration pneumonia
Describe the progression to uraemic pneumonia
Severe uraemia causes increased permeability of the blood-air barrier and therefore causes pulmonary oedema
Describe the 2 classes of lipid pneumonia
- Endogenous (accumulation of lipids in pulmonar macrophages)
- Exogenous (inhalation of oil, macrophages infiltrte the alveoli and cause thickening)
List the 3 normal mechanisms of the lung that protect it from pulmonary oedema
- Alveolar epithelium and intracellular junctinos are impermeable to fluid
- Interstitium of alveolar septase is at a lower pressure than intra-alveolar pressure
- Interstitial pressure becomes increasingly sub-atmospheric towards the fascia surrounding vessels and the pulmonary hilus
List 4 classifications of pulmonary tumors
- Bronchial papilloma
- Bronchial adenoma/carcinoma
- Bronchioalveolar adenoma/carcinoma
- Carcinoid (more in humans than animals)