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1
Airways
82. Catarrhal, fibrinous (croupous) and
aspiration (ichorous) pneumonia (in
general)
Structure of
the lobuleBronchiolus terminalis
Bronchuli respiratorii
Ductuli
alveolares
InfundibulumAlveolus
ACINUS
Structure of the alveolus
• Basement membrane
• pneumocyte I.– respiratory cell
• pneumocyte II.– surfactant (anti-atelectatic
factor)
– participant in regeneration
• pneumocyta III.– dog, rat– cell of the
vegetative/autonomic nervous system
• alveolar macrophage• alveolar pores• capillary network
Environment of
the alveoli
United basement membrane in
between to ease the gas exchange
Blood and air barrier
Pneumonias in animals
• Mostly caused by microorganisms– viruses, bacteria
– fungi, parasites
– other causes
• allergy, inhalation of hot gases, aspiration
• Age – special features– fetuses
– newborns
– sucking animals
– young animals
– adults
Pneumonias in fetuses
• Pathogens– Viruses: transplacental infection – Bacteria, fungi: first inducing placentitis, infection of
the amniotic fluid, infection of the fetus and the lung
• calf – BHV-1 (bovine rhinotracheitis), PI-3-virus infection– Brucella abortus, Listeria monocytogenes,
Chlamydophila psittaci, Actinomyces pyogenes, Mycoplasma sp., Ureaplasma sp. stb.
– Aspergillus sp.
• foal – EHV-1 (equine rhinopneumonitis)
• dog – CHV-1 (canine herpesvirus infection)
– Mycoplasma canis, Chlamydophila psittaci
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Pneumonia in newborns(perinatal pneumonias)
• neonatal pneumonia (collective category)– Aerogenous infection before the newborn got the
colostrum (in state of hypogammaglobulinaemia)
– inhalation of different bacteria
• calf, foal, goat Streptococcus sp.
• piglet Streptococcus sp., E. coli
• birds E. coli
– Local process continues often to septicemia
• meconium aspiration syndrome– aspiration during parturition, typical
– or obturation, or pneumonia due to pathogens
Forms of pneumonias
• definition– inflammatory process in the parenchyma of the lung often
accompanied with the lesions of the smaller or larger bronchi
• Forms– bronchoalveolar
• serous, desquamative, catarrhal, suppurative, fibrinous (croupous)
– interstitial
– granulomatous
– embolic-metastatic
– aspiration
– special
Bronchopneumonias:
Inflammation →→→→
hyperaemia, edema →→→→
neutrophils, macrophages
→→→→ epithelial gaps↑↑↑↑,
vascular permeability↑↑↑↑ →→→→
plasma fluid, proteins →→→→
airspace↓↓↓↓
Serous bronchopneumonia
Desquamative bronchopneumonia
Desquamative bronchopneumonia Desquamative bronchopneumonia
3
Serous
bronchopneumonia
Normal shape, slightly enlarged,
darker, gland-like by palpation,
doesn’t crepitate when cut, clear
liquid oozes to the cut surface
Catarrhalbronchitis
Desquamative pneumonia
Bronchoalveolar pneumonia(bronchopneumonia)
Extension:
lobules - lobular
lobes - lobal
focal - pseudolobular
Fibrinous (croupous) pneumonia• spreads quickly → entire lobes are affected - “Lobar pneumonia”• Development
– Congestion, hemorrhage, massive exudation, fibrin accumulation
– Fibrin → pleural surface = sero-fibrinous pleuritis
• Appearance– intense redness, firmer texture, “consolidation”, hepatization (red~, gray~).
– Dilation and thrombosis of lymph vessels → edema → thick septae → marbled appearance
– Focal coagulative necrosis. “Sequestra”.
– Histology
• massive exudation →→→→ fluid obliterates airspace. Neutrophils, macrophages. Fibroblasts
• Stages– initial phase
• stadium incrementi s. hyperaemicum– phase of hepatisation (std. hepatisationis)
• red hepatisation (std. h. rubrae)• grey hepatisation (std. h. griseae)• yellow hepatisation (std. h. flavae)
– phase of resolution (std. resolutionis)
• nasal discharge: mucoid or mucopurulent (P. m., B. b., Str.)
Croupous (fibrinous) pneumonia Croupous (fibrinous) pneumonia
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Croupous pneumonia Croupous pneumonia – stadium incrementi
Croupous pneumonia - hepatisation Grey hepatisation
Croupous pneumonia – hemorrhagic character Healing of the croupous pneumonia
• restitutio ad integrum– if the integrity of the tissue structure is maintained
– freed enzymes of the degenerated neutrophils cause
– fibrinolysis
• partially absorbtion (lymph vessels)
• partially expectoration
– epithel layer of the acini regenerates
• restitutio cum defectu– connective tissue proliferation from the wall of the
respiratory ducts
– carnificatio pulmonum
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Croupous pneumonia
• Due to direct (thrombotic) effect of the pathogen– Smaller or larger necrotic foci
– Sometime hemorrhagic character
– Secondary ichorous pneumonia on the affected areas
• Cause of death:– Suffocation or heart failure
– Following croupous pneumonia
• Metastatic foci – focal necrotizing-purulent-ichorouspneumonia
• Allergic reaction in horses
– Hemorrhagic purpura, septic pododermatitis, uveitis, urticaria
Croupous pneumonia
Pathology of the croupous pneumonia
• shape maintained
• enlarged
• marbled
• liver-like (in stages of hepatisation)
• No crepitation on cutting!
• cut surface
– mottled, homogenous
– dry, uneven, granular
Aspiration pneumonia
• Different aspirated substances– amniotic fluid– milk, saliva, food, drinking water, blood
– fluid used for gastric lavage, contrast medium used forfilling the GI tract
– eructated or vomited gastric content
• Consequences are different according to– what type of material and what amount is aspirated– where did the substance go– if there where any putrefactive bacteria present
Aspiration pneumonia Aspiration pneumonia
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Aspiration pneumonia Aspiration pneumonia
• Putrid bronchitis
– Putrefactive bacteria colonize in the mucous membrane of the bronchi
– the mucous membrane necrotizes
– accompanied with putrid smell, the tissue debris becomes soft fluid
– all the layers of the bronchi are affected
– if there is enough time, the lungs also become affected
• usually the animal dies because of the absorbed toxins
Ichorous pneumonia• Way of infection:
– Aerogenous infection (aspiration)
• putrid bronchitis first, than spreading to the lungs
• starts from the airways
– lympho-haematogenous infection may occur
• disseminated foci
• from the blood vessels of the interstitium
• Due to putrefactive bacteria
– coagulation necrosis
– secondary softening in the necrotized areas
• putrid smell, histolytic tissue debris causing intoxication
(sapraemia)
– acute ichorous abscess, ichorous cavern (cavity)
• Slow, delayed demarcation
Ichorous pneumonia
83. Interstitial, suppurativeand embolic pneumonias
(in general)
Interstitial pneumonia
• Majority of the lesions
– In the interstitium
• Most typical lesions:
– acute, subacute, chronic proliferative inflammation
– besides proliferative processes immunpathological
processes, accumulation of immune cells
• Appearance:
– intralobular (interalveolar)
– interlobular – between the lobules
– peribronchial – around the small bronchi
7
Intralobular (interalveolar) interstitial pneumonia Mild proliferation of the alveolar interstitiumIntralobular (interalveolar) interstitial pneumonia
Severe proliferation of the alveolar interstitiumIntralobular (interalveolar) interstitial pneumonia
Immunpathologic process
Intralobular (interalveolar) interstitial pneumonia
Peribronchial interstitial pneumonia Interstitial pneumonia
• Proliferative processes in the alveoli
– Epithelisation
• pneumocyta II.
– Pseudoepithelisation
• alveolar macrophages
• Age of the process– acute – histiocyte and macrophage proliferation
– subacute – pronounced cell proliferation
– chronic – severe fibrosis
8
Pathogen has an effect inside the alveoliIntralobular (interalveolar) interstitial pneumonia
Epithelisation
Pseudoepithelisation Chronic interstitial pneumonia
Suppurative pneumonia
(pneumonia purulenta)
• Typically embolic or metastatic
• If hematogenous:– Purulent process somewhere in the body → distributed
abscesses in the lung (no surrounding inflammation)
• If bronchiogenous:– First catarrhal or croupous pneumonia occurs and
secondary purulent foci are formed
• Pathogens: – cattle/pig → Arcanobacterium (Actinomyces) pyogenes
– rabbit → Staphylococcus aureus– horse → Streptococcus equi, Rhodococcus equi
Purulent bronchopneumonia
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Purulent bronchopneumonia
Pneumonia with granulome formation
• Accompaying other disease– Lympho-hematogenous metastasis
• Embolic-metastatic pneumonia
• Possible nodules– necrotic foci– purulent (ichorous) abcesses
– ichorous foci
• Appearance:– solitaer focus (smaller - larger)
– evenly disseminated foci– foci of the same age / or prolonged form
Necrotic pneumonia Sequestrum formation after necrotic pneumonia
Mass of necrotic lung parenchyma
seprated from viable lung tissue by
purulent exudate and usually
encased in a fibrous capsule
10
Embolic-metastatic pneumonia Chronic purulent abscess formation
(cut surface)
Port of entry Purulent-ichorous pneumonia
Granulomatous pneumonia Granulomatous pneumonia
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Granulomatous pneumonia Locus minoris resistanciae
Special pneumonias• Actinobacillus pleuropneumonia
– serous-hemorrhagic-proliferative-necrotizing
• in hours, death in 1-2 days
• pronounced macrophage proliferation
• extended demarcation
– sero-fibrinous pleuritis
• perifocal edema
• Anthrax
– Aerogenous infection (piglet inhales the spores)
– Serous, hemorrhagic, necrotizing pneumonia
– Spore reaches the deep areas of the lung, starts to
proliferate → rapid course