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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

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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

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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

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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

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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