Pneumonia Flashcards
(50 cards)
What are the 5 broad classifications (morphologic) of pneumonia?
Bronchopneumonia Lobar pneumonia Bronchointerstitial pneumonia Interstitial pneumonia Multifocal pneumonia
What is the usual route of infection for bronchopneumonia? What is the usual causative agent (i.e bacteria, virus, fungus)
Inhalation of bacteria
Where in the bronchial tree does inflammation localise to in bronchopneumonia? Why?
The junction of the distal bronchioles and alveoli
Because of the sudden reduction in air velocity and multiple points of branching
What is the usual distribution of bronchopneumonia in the lung?
Cranioventral
What is one exception to the usual distribution of bronchopneumonia in the lung? Where is it instead?
Pneumonia caused by parasitic lungworm (verminous) is usually dorsocaudal. e.g Metastrongylus in pigs
In which species is bronchopneumonia less likely to resolve? Why?
Cattle and pigs
Distinct lobular septa inhibiting exudate drainage and inflammatory cell clearance
What histological factor is significant in distinguishing bronchopneumonia from bronchointerstitial pneumonia?
Damage to the pulmonary interstitium
What type of inflammation is typical of bronchopneumonia?
Suppurative
What are three possible consequences of chronic bronchopneumonia?
Atelectasis > degeneration and fibrosis of collapsed parenchyma
Pulmonary abscessation
Alveolar emphysema
What are three common causes of bronchopneumonia? Where might these organisms have come from?
Streptococcus spp.
Staphylococcus spp.
Bordetella bronchiseptica
All are commensal organisms of the URT that take advantage of respiratory tract compromised by viral infection, noxious gas exposure, cold air etc
What are two important distinguishing features of Lobar pneumonia related to bronchopneumonia?
Lobar is more rapidly progressive and severe
Typically lobar involves an entire lobe of lung, or more
What is the usual distribution of lobar pneumonia in the lung?
Cranioventral
What is the exception to the usual distribution of lobar pneumonia? Where is it located?
Pneumonia caused by Actinobacillus pleuropneumoniae in pigs
Usually dorsocaudal
What sort of inflammation is usual for lobar pneumonia? Which other condition commonly occurs at the same time?
Fibronecrotising Fibrinous pleuritis ( = 'pleuropneumonia' )
How much exudate can you squeeze from a lobar pneumonia sample at post mortem?
Not much - airways are mostly blocked by fibrin
How do you get ‘sequestrae’ in lobar pneumonia? What significance might this have for the resolution of the disease?
Erosion of pulmonary artery by inflammation > thrombosis and loss of blood supply > ischaemia and necrosis of dependent tissue > fibrosis. Causative organism can remain in these sequestra
Why does the animal commonly die in lobar pneumonia when only 20 - 40% of lung function is lost?
Because the causative organism toxins are released into the blood > toxaemia
What are three potential causes of lobar pneumonia?
Mannheimia haemolytica (ruminants) Pasteurella multocida (cattle and sheep) Actinobacillus pleuropneumoniae (pigs)
What is the usual distribution of bronchointerstitial pneumonia?
Cranioventral
What is the usual route of infection for bronchointerstitial pneumonia?
Aerogenous (inhaled)
What is the major distinguishing feature of this pneumonia from bronchopneumonia? Can they be differentiated grossly?
No - need histopath to tell them grossly
Bronchointerstitial has damage to the alveolar walls (see lymphocytes accumulate within)
What are three potential causes of bronchointerstitial pneumonia?
Parainfluenza viruses - cattle and sheep
Influenza viruses - horses and pigs
Paramyxovirus such as canine distemper in dogs
What is the most common cause of bronchoninterstitial pneumonia in Australia? Does this come under another category of pneumonia as well?
Mycoplasma infection
- counts as enzootic pneumonia
Which species is enzootic pneumonia an issue in? What age group? When is the risk period?
Calves, lambs and pigs in intensively farmed enterprises
Infection typically occurs as maternal immunity wanes
