Difference between revisions of "Lungs Inflammatory - Pathology"

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

Revision as of 18:05, 19 February 2011

Pneumonia Overview

Pneumonia - Introduction and Classification

Acute fibrinous pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
  • Pneumonia
    • Inflammation that takes place in the alveoli and their walls
    • Can be grouped either according to
      • Nature of the inflammatory process
      • Aetiological agent
      • Pattern of the lesion


Bronchopneumonia

Bronchointerstitial Pneumonia

Lobar Pneumonia

Interstitial Pneumonia

Embolic pneumonia

  • Lung inflammation caused by haematogenous spread of infections into the lung
  • No orientation around airways and can be in any lung region but most often affects caudal lobes
  • The inflammation is oriented around blood vessels, usually venules or alveolar capillaries in which septic emboli localise


Granulomatous pneumonia

Granulomatous mycotic pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
  • Variable number and distribution of caseous or non-caseous granulomas throughout the lung
  • Must be distinguished from neoplasms
  • Calcification may occur
  • Caused by agents resistant to phagocytosis, mostly fungi, Mycobacterium bovis, Rhodococcus equi, foreign material, FIP
  • Micro: centre of necrotic tissue surrounded by macrophages, connective tissue and lymphocytes


Verminous pneumonia

Parasitic pneumonia (Image sourced from Bristol Biomed Image Archive with permission)


Stages of pneumonia

Acute exudative pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
Acute exudative pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
  • Regardless of the pattern, all pneumonias pass through three stages:
    • Exudative phase
      • In this initial stage inflammatory exudate pours into alveolar spaces and alveolar capillaries are congested
      • Type I alveolar epithelial cells are highly sensitive to injury and cannot proliferate in response to injury
      • Necrosis and sloughing of injured type I cells, denuding alveolar spaces of lining epithelium
      • Neutrophils begin to enter alveolar spaces distended with inflammatory oedema
    • Proliferative phase
      • 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
      • 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
      • 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”
    • Repair phase
      • Resolution of pneumonia is accomplished by transformation of type II cells to type I cells


Pulmonary abscesses

Multiple pulmonary abscesses (Image sourced from Bristol Biomed Image Archive with permission)
  • Commonly found post mortem
  • Can be a consequence of:
  1. Septic emboli lodging in the pulmonary vessels
  2. Extension from severe focal suppurative bronchopneumonia
  3. Aspiration of foreign material (see aspiration pneumonia)
  4. Direct penetration
  • 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.

Infectious causes of pneumonia

. VIRAL BACTERIAL FUNGAL PARASITIC
Dogs Canine distemper usually secondary Blastomyces dermatitidis Angiostrongylus vasorum
. Infectious canine tracheitis bronchopneumonia: Bordetella bronchiseptica, Staphylococci, Streptococci, Coliforms Histoplasma capsulatum Toxoplasma gondii
. Herpes virus . . .
Cats Feline calicivirus bronchopneumonia: Pasteurella sp., Streptococcus spp. . Aelurostrongylus abstrusus
. . Feline chlamydiosis . .
Horses Equine rhinopneumonitis Strangles Pneumocystis carinii Parascaris equorum
. Equine influenza Glanders . .
. Equine viral arteritis Rhodococcus equi . .
Cattle Parainfluenza- 3 Necrotic Laryngitis . Dictyocaulus viviparus
. . Pneumonic pasteurellosis . .
. . Contagious bovine pleuropneumonia . .
. . Enzootic pneumonia of calves . .
. . Acute exudative pneumonia . .
. . Mycoplasmal pneumonia . .
. . Mycobacterium bovis - tuberculosis . .
. . bronchopneumonia: Pasteurella sp., Corynebacterium pyogenes . .
Sheep Maedi Visna bronchopneumonia: Corynebacterium pyogenes . Muellerius capillaris
. Parainfluenza- 3 Enzootic pneumonia of lambs . .
. Sheep Pulmonary Adenomatosis Pseudomonas (Malleomyces) pseudomallei . .
Pigs Inclusion body rhinitis Enzootic pneumonia of pigs . Ascaris suum
. Swine influenza Actinobacillus pleuropneumoniae . .
. Porcine reproductive and respiratory syndrome Necrotic Laryngitis . .
. Postweaning multisystemic wasting syndrome Pasteurella multocida . .
. Porcine respiratory coronavirus Contagious porcine pleuropneumonia . .
. . Glasser's disease . .
. . Bordetella bronchiseptica . .
. . bronchopneumonia: Pasteurella spp., Corynebacterium pyogenes, also Streptococcus spp., Tuberculosis . .


Other forms of pneumonia

Aspiration pneumonia

Acute necrotising pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
Aspiration pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
  • 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
  • Mild bronchopneumonia can develop into a severe necrotising pneumonia and in very severe cases can progress to gangrenous pneumonia (below)
  • In Cattle
    • Associated with poor husbandry
    • Regurgitated ruminal content
    • Cranio-ventral distribution
    • Respiratory insufficiency secondary to congenital cardiac disease
  • In Horses
    • Most commonly in right ventral lung lobe (most rostral secondary bronchus leads to right accessory lobe)
    • Risk factors:
      • Oesophageal obstruction
      • Spontaneous reflux (GI obstruction, equine grass sickness)
      • Dysphagia
      • Iatrogenic
        • Nasogastric tube in the wrong place
  • In Dogs


Gangrenous pneumonia

Gangrenous pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
  • Can occur following severe infections in which tissue becomes necrotic and is then invaded by putrefactive saprophytes, however this is rare.
  • The usual cause is administration of medicines (intended for the oesophagus!) or as a sequel to aspiration pneumonia
  • The dead tissue undergoes liquefactive necrosis forming a cavity which is surrounded by intense hyperaemia and inflammation


Lipid pneumonia

Lipid pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
  • Associated with inhalation of oil, paraffin, etc.
  • Reaction dominated by macrophages which fill the alveoli and interstitial thickening (mononuclear cells and fibrosis)
  • Tends to acumulate in ventral regions bilterally
  • Occurs subclinically in cats, sometimes dogs, unrelated to aspiration
  • Gross lesion:
    • Multifocal, firm, white nodules
  • Microscopic lesions:
    • Macrophages full of lipid forming foam within alveoli
    • Interstitial lymphocyte and plasma cell infiltration, fibrosis


Uraemic pneumonia

  • Severe uraemia causes increased permeability of the blood-air barrier and therefore can cause pulmonary oedema
  • In addition to the oedema, there may also be degeneration and calcification of smooth muscle and connective tissue fibres
  • Lungs do not collapse on opening the thorax in severe cases


Foetal pneumonia


Test yourself with the Lungs Pathology Flashcards

Lungs Pathology Flashcards

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