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− | [[Pneumonia Overview]]
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− | ==Pneumonia - Introduction and Classification==
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− | [[Image:Acute fibrinous pneumonia.jpg|right|thumb|150px|<small><center>Acute fibrinous pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | *Pneumonia
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− | **Inflammation that takes place in the '''alveoli and their walls'''
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− | **Can be grouped either according to
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− | ***Nature of the inflammatory process
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− | ***Aetiological agent
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− | ***Pattern of the lesion
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− | *Patterns of lung inflammation vary depending on the aetiology, route and method of exposure and multiple host factors including age, general health, and immune status
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− | **There are five general patterns of pneumonia:
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− | ***[[Bronchopneumonia]]
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− | ***[[Bronchointerstitial Pneumonia]]
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− | ***[[Lobar Pneumonia]]
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− | ***[[Interstitial Pneumonia]]
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− | ***[[Embolic Pneumonia]]
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− | [[Category:Pneumonia]]
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− | =='''[[Bronchopneumonia]]'''==
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− | =='''[[Bronchointerstitial Pneumonia]]'''==
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− | =='''[[Lobar Pneumonia]]'''==
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− | =='''[[Interstitial Pneumonia]]'''==
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− | =='''[[Embolic Pneumonia]]'''==
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− | =='''[[Granulomatous Pneumonia]]'''==
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− | =='''[[Verminous Pneumonia]]'''==
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− | =Stages of pneumonia=
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− | [[Image:Acute exudative pneumonia.jpg|right|thumb|150px|<small><center>Acute exudative pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | [[Image:Acute exudative pneumonia - gross.jpg|right|thumb|150px|<small><center>Acute exudative pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | *Regardless of the pattern, all pneumonias pass through three stages:
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− | **'''Exudative phase'''
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− | ***In this initial stage inflammatory exudate pours into alveolar spaces and alveolar capillaries are congested
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− | ***Type I alveolar epithelial cells are highly sensitive to injury and cannot proliferate in response to injury
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− | ***Necrosis and sloughing of injured type I cells, denuding alveolar spaces of lining epithelium
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− | ***[[Neutrophils|Neutrophils]] begin to enter alveolar spaces distended with inflammatory oedema
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− | **'''Proliferative phase'''
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− | ***Type II alveolar cells (less sensitive to and can proliferate in response to injury) begin to proliferate within 24 hours and eventually line the alveolar walls denuded of type I cells ***By 6 days cuboidal type II cells can completely line the alveoli
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− | ***Proliferation of type II cells marks the shift from the exudative to the proliferative stage of pneumonia, also heralded by decreased blood flow in alveolar capillaries
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− | ***Because the original squamous type I cells have been replaced by cuboidal type II cells, the microscopic appearance of pneumonic lungs at about 1 week has been described as “alveolar epithelialization”, “alveolar adenomatosis”, or “bronchiolisation of alveoli”
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− | **'''Repair phase'''
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− | ***Resolution of pneumonia is accomplished by transformation of type II cells to type I cells
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− | =Pulmonary abscesses=
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− | [[Image:Multiple pulmonary abscesses.jpg|right|thumb|150px|<small><center>Multiple pulmonary abscesses (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | *Commonly found post mortem
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− | *Can be a consequence of:
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− | # [[Pulmonary Embolism, Thrombosis and Infarction|'''Septic emboli''']] lodging in the pulmonary vessels
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− | # '''Extension''' from severe focal suppurative [[Lungs Inflammatory - Pathology#Bronchopneumonia|bronchopneumonia]]
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− | # '''Aspiration''' of foreign material (see [[Lungs Inflammatory - Pathology#Aspiration pneumonia|aspiration pneumonia]])
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− | # Direct '''penetration'''
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− | *The pattern of abscessation can suggest the aetiology i.e. multiple widespread abscesses suggest a haematogenous origin; isolated cranioventral abscesses usually arise from suppurative pneumonia.
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− | ='''Infectious causes of pneumonia'''=
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− | {| cellpadding="5" cellspacing="0" border="1"
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− | | [[:Category:Respiratory Viral Infections|'''VIRAL''']]
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− | | [[:Category:Respiratory Bacterial Infections|'''BACTERIAL''']]
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− | | [[:Category:Respiratory Fungal Infections|'''FUNGAL''']]
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− | | [[:Category:Respiratory Parasitic Infections|'''PARASITIC''']]
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− | | '''Dogs'''
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− | | [[Canine Distemper Virus|Canine distemper]]
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− | | usually secondary
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− | | [[Blastomycosis|''Blastomyces dermatitidis'']]
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− | | [[Angiostrongylus vasorum|''Angiostrongylus vasorum'']]
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− | | [[Canine Infectious Tracheobronchitis|Infectious canine tracheitis]]
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− | | bronchopneumonia: ''[[Bordetella bronchiseptica]], [[:Category:Staphylococcus species|Staphylococci]], [[:Category:Streptococcus species|Streptococci]], Coliforms''
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− | | [[Histoplasmosis|''Histoplasma capsulatum'']]
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− | | ''[[Toxoplasma gondii]]''
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− | | [[Canine Herpesvirus 1|Herpes virus]]
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− | | '''Cats'''
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− | | [[Feline Calicivirus|Feline calicivirus]]
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− | | bronchopneumonia: ''[[:Category:Pasteurella and Mannheimia species|Pasteurella sp.]], [[:Category:Streptococcus species|Streptococcus spp.]]''
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− | | ''[[Aelurostrongylus abstrusus]]''
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− | | [[Chlamydiosis, Feline|Feline chlamydiosis]]
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− | | '''Horses'''
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− | | [[Equine Rhinopneumonitis|Equine rhinopneumonitis]]
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− | | [[Strangles|Strangles]]
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− | | [[Pneumocystis carinii|''Pneumocystis carinii'']]
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− | | ''[[Parascaris equorum]]''
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− | | [[Equine Influenza|Equine influenza]]
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− | | [[Glanders|Glanders]]
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− | | [[Equine Viral Arteritis|Equine viral arteritis]]
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− | | [[Rhodococcus equi|''Rhodococcus equi'']]
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− | | '''Cattle'''
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− | | [[Bovine Parainfluenza - 3|Parainfluenza- 3]]
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− | | [[Necrotic Laryngitis]]
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− | | ''[[Dictyocaulus viviparus]]''
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− | | [[Pneumonic Pasteurellosis|Pneumonic pasteurellosis]]
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− | | [[Contagious Bovine Pleuropneumonia|Contagious bovine pleuropneumonia]]
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− | | [[Enzootic Pneumonia - Calves|Enzootic pneumonia of calves]]
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− | | [[Acute Exudative Pneumonia|Acute exudative pneumonia]]
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− | | [[Enzootic Pneumonia - Calves|''Mycoplasmal'' pneumonia]]
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− | | [[Tuberculosis - Cattle|''Mycobacterium bovis'' - tuberculosis]]
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− | | bronchopneumonia: [[:Category:Pasteurella and Mannheimia species|''Pasteurella sp.'']], ''[[Corynebacterium pyogenes]]''
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− | | '''Sheep'''
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− | | [[Visna-Maedi Virus|Maedi Visna]]
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− | | bronchopneumonia: ''[[Corynebacterium pyogenes]]''
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− | | [[Muellerius|''Muellerius capillaris'']]
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− | | [[Bovine Parainfluenza - 3|Parainfluenza- 3]]
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− | | [[Enzootic Pneumonia - Lambs|Enzootic pneumonia of lambs]]
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− | | [[Sheep Pulmonary Adenomatosis]]
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− | | [[Melioidosis|''Pseudomonas (Malleomyces) pseudomallei'']]
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− | | '''Pigs'''
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− | | [[Porcine Cytomegalovirus|Inclusion body rhinitis]]
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− | | [[Enzootic Pneumonia - Pigs|Enzootic pneumonia of pigs]]
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− | | [[Ascaris suum|''Ascaris suum'']]
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− | | [[Swine Influenza|Swine influenza]]
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− | | [[Actinobacillus pleuropneumoniae|''Actinobacillus pleuropneumoniae'']]
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− | | [[Porcine Reproductive and Respiratory Syndrome|Porcine reproductive and respiratory syndrome]]
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− | | [[Necrotic Laryngitis]]
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− | | [[Porcine Circoviruses|Postweaning multisystemic wasting syndrome]]
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− | | [[Pasteurellosis - Pigs|''Pasteurella multocida'']]
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− | | [[Porcine Respiratory Coronavirus|Porcine respiratory coronavirus]]
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− | | [[Contagious Porcine Pleuropneumonia|Contagious porcine pleuropneumonia]]
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− | | [[Glasser's Disease|Glasser's disease]]
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− | | [[Atrophic Rhinitis|''Bordetella bronchiseptica'']]
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− | | bronchopneumonia: [[:Category:Pasteurella and Mannheimia species|''Pasteurella'' spp.]], ''[[Corynebacterium pyogenes]]'', also [[:Category:Streptococcus species |''Streptococcus'' spp.]], [[Tuberculosis - Pigs|Tuberculosis]]
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− | ='''Other forms of pneumonia'''=
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− | ===Aspiration pneumonia===
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− | [[Image:Acute necrotising pneumonia.jpg|right|thumb|150px|<small><center>Acute necrotising pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | [[Image:Inhalation pneumonia.jpg|right|thumb|150px|<small><center>Aspiration pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | *Response of the lungs to aspirated foreign material will depend on the nature of the material (e.g. food), the bacterial load and the distribution of the material within the lungs
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− | *Mild bronchopneumonia can develop into a severe necrotising pneumonia and in very severe cases can progress to gangrenous pneumonia (below)
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− | *In Cattle
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− | **Associated with poor husbandry
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− | **Regurgitated ruminal content
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− | **Cranio-ventral distribution
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− | **Respiratory insufficiency secondary to [[:Category:Cardiovascular System - Developmental Pathology|congenital cardiac disease]]
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− | *In Horses
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− | **Most commonly in right ventral lung lobe (most rostral secondary bronchus leads to right accessory lobe)
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− | **Risk factors:
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− | ***[[Oesophagus - Anatomy & Physiology|Oesophageal]] obstruction
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− | ***Spontaneous reflux (GI obstruction, equine grass sickness)
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− | ***[[Respiratory System Clinical Signs - Pathology#Dysphagia|Dysphagia]]
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− | ***Iatrogenic
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− | ****Nasogastric tube in the wrong place
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− | *In Dogs
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− | **Most commonly [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomited]]/regurgitated material or contrast medium introduced into airways
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− | **In severe acute cases may die from septic shock
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− | **In chronic cases -> [[Lungs Inflammatory - Pathology#Bronchopneumonia|bronchopneumonia]]
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− | **Common sequel to [[Myasthenia Gravis|myasthenia gravis]], [[Megaoesophagus|megaoesophagus]] or [[Persistent Right Aortic Arch|persistent right aortic arch]]
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− | [[Category:Pneumonia]]
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− | ===Gangrenous pneumonia===
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− | [[Image:Gangrenous pneumonia.jpg|right|thumb|150px|<small><center>Gangrenous pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | *Can occur following severe infections in which tissue becomes necrotic and is then invaded by putrefactive saprophytes, however this is rare.
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− | *The usual cause is administration of medicines (intended for the oesophagus!) or as a sequel to aspiration pneumonia
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− | *The dead tissue undergoes liquefactive necrosis forming a cavity which is surrounded by intense hyperaemia and inflammation
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− | [[Category:Pneumonia]]
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− | ===Lipid pneumonia===
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− | [[Image:Lipid pneumonia.jpg|right|thumb|150px|<small><center>Lipid pneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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− | *Associated with inhalation of oil, paraffin, etc.
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− | *Reaction dominated by macrophages which fill the alveoli and interstitial thickening (mononuclear cells and fibrosis)
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− | *Tends to acumulate in ventral regions bilterally
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− | *Occurs subclinically in cats, sometimes dogs, unrelated to aspiration
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− | *Gross lesion:
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− | **Multifocal, firm, white nodules
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− | *Microscopic lesions:
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− | **Macrophages full of lipid forming foam within alveoli
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− | **Interstitial lymphocyte and plasma cell infiltration, fibrosis
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− | [[Category:Pneumonia]]
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− | ===Uraemic pneumonia===
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− | *Severe uraemia causes increased permeability of the blood-air barrier and therefore can cause [[Pulmonary Oedema|pulmonary oedema]]
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− | *In addition to the oedema, there may also be degeneration and calcification of smooth muscle and connective tissue fibres
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− | *Lungs do not collapse on opening the thorax in severe cases
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− | [[Category:Pneumonia]]
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− | ===Foetal pneumonia===
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− | *Especially foals and farm species
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− | *Due to aspiration of amniotic fluid contaminated with meconium and bacteria
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− | **Secondary to fetal distress
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− | **Microscopic lesions of [[Lungs Inflammatory - Pathology#Bronchopneumonia|bronchopneumonia]]
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− | **Involves all lobes (versus postnatal bronchopneumonia)
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− | *Haematogenous spread
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− | **Causes [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]]
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− | **Often caused by ''Listeria monocytogenes'', ''Salmonella'' spp. or ''Chlamydia psittaci''
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− | *In viral abortions
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− | **Cause [[Lungs Inflammatory - Pathology#Bronchointerstitial pneumonia|bronchointerstitial pneumonia]]
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− | **E.g.: [[Infectious Bovine Rhinotracheitis|IBR]], [[Bovine Parainfluenza - 3|PI-3]] and [[Equine Rhinopneumonitis|equine viral rhinopneumonitis]]
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− | [[Category:Pneumonia]]
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− | =Test yourself with the Lungs Pathology Flashcards=
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− | [[Lungs_Flashcards_-_Pathology|Lungs Pathology Flashcards]]
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