Inflammation and the lung

Question 1

Inflammation terminology

Answer 1

in general: add suffix “itis” to start of anatomical name

e.g. tonsilitis, pharyngitis

sometimes greek or latin is used i.e. stomatitis and gastritis

Question 2

Why are lungs vulnerable to airborne infection?

Answer 2

huge area of alveoli

large volume of air entering the lungs continuously

high concentration of noxious elements in the air

Question 3

Why are lungs vulnerable to problems via hematogenous spread?

Answer 3

lungs vulnerable to blood-borne microbes/toxins/emboli

Entire output of RV enters the lungs; roughly 9% of total blood volume is in the lungs

largest capillary bed in the body= pulmonary capillary bed

1ml of blood occuppies 16km of capillary bed

Question 4

Important lung features

Answer 4

bronchi: supported by cartilage, efficient mucociliary defenses
bronchioles: transition zone from airway/conducting–>gas exchange; diminished mucociliary defenses; no supporting cartilage; clara cells are metabolically active (i.e. producing reacitve metabolites); alveolar macs and n’phils accumulate–> can release damaging oxidative free radicals.

Question 5

Important feature of alveoli

Answer 5

delicate, thin-walled

vascular endothelium, basal lamina (alveolar interstitium), thin type I pneumocytes, granular tpye II pneumocytes which produce surfactant

NB: type II can act to repair damage to type I by flattening out.

Question 6

Normal UPPER respiratory flora

Answer 6

most proximal region of conducting system ONLY (nasal cavity, pharynx, larynx)

Manheimia hemolytica in cattle; pasturella multocida in cats, cattle and pigs; bordetella bronchiseptica in dogs and pigs

Question 7

Bronchopneumonia

Answer 7

affects cranial aspect of lungs d/t inhaled organisms

common in domestic species

initiates in bronchi and extends into surrounding parenchyma and can involve all airways (including alveoli)

Question 8

interstitial pneumonia

Answer 8

see rib imprints

increased cellularity, big firm lungs which don’t deflate

inflammation of the pulmonary interstitium (other than the airways); usually involves alveolar epithelium

Question 9

Granulomatous pneumonia

Answer 9

TB!

parasitic pneumonia: parasites trigger eosinophils which trigger macrophages

Question 10

embolic pneumonia

Answer 10

collateral circulation, vast blood supply–> hematagenous spread of organisms/debris

pneumonitis: pneumonia with a lot of fibrous material

Question 11

Causes of bronchopneumonia

Answer 11

bacteria

mycoplasma and viruses- with secondary bacteria

aspirate food or gastric contents

Question 12

Pathogenesis of bronchopneumonia

Answer 12

inhaled agents–> injury and subsequent inflammation at the bronchoalveolar junction–>acute inflammatory response–> exudation of fluid and plasma proteins into bronchioles and alveoli–> recruitment of alveolar macs and emigration of neutrophils in blood vessels.

nb: can get diphtheritic membrane

Nb: cranioventral aspect of lung commonly affected.

Question 13

Suppurative bronchopneumonia

Answer 13

exudate: purulent or mucopurulent
distribution: can be patchy, confluent areas or whole lobes
causes: pasturella multocida, brodetella bronchispetica, arcanobacterium pyogenes (truperella pyogenes), strep spp., E. coli

Bland aspiration–> not toxic, but something that shouldn’t be in lungs

Parainfluenza 3, respiratory syncitial virus and distemper.

Question 14

Fibrinous bronchopneumonia

Answer 14

exudate: fibrin, oedema, n’phils, necrosis

Distribution: spreads rapidly within and between lobules- often affects large confluent areas/whole lobes

Causes: manheimia hemolytica, actinobacillus pleuropneumonia

Irritant aspiration

mycoplasma mycoides

Histopath: necrosis of alveolar walls; dense fibrinous edema fluid

Fibrinous adhesions seen on lung surface.

Question 15

Acute fibrinous bronchopneumonia in calves

Answer 15

manheimia hemolytica–> colonizes lower respiratory tract

-produces leukotoxin which damages white cells–> lyses alveolar macrophages and neutrphils

lysosomal contents are released–> once outwith cells, tissue necrosis

-tissue necrosis and fibrinous bronchopneumonia

extensive deposition of fibrin in interlobular and interlobar septa

suppurative or fibrinous is determined by severeity of injury: can co-exist

Question 16

Possible sequelae to acute bronchopneumonia

Answer 16

resolution

chronic pneumonia–> BALT hyperplasia, bronchiolar goblet cell metaplasia (increased secretion), fibrosis

Abscess formation

pleursy/pleuritis

death

Question 17

Cuffing pneumonia

Answer 17

mycoplasmal bronchopneumonia

hyperplasia of balt–> squishes bronchiole

Question 18

enzootic pneumonia

Answer 18

collapse and consolidation: collapse of alveoli due to peribronchial cuffing; consolidation due to movement of cells and fluid into alveoli.

Question 19

Chronic suppurative bronchopneumonia

Answer 19

mucus in airways

mucopurulent: normal lung collapsed, a few areas of overinflation

Question 20

verminous (parasitic) pneumonia due to dictyocaulus filaria

Answer 20

interstitial: larval migration
bronchitis: intrabronchial adults
granulomatous: aberrant parasites, dead larvae or eggs

LNs with be green with parasitic infection due to presence of eosinophils

areas of collapse and overinflation

Question 21

Muelleris capillaris

Answer 21

non-immune–> doesn’t cause clinical disease

younger sheep get dramatic puffy coalescing lesions

in older animals, lead shot lesions–> IR walls off organisms with eosinophils–> granulomatous inflammation walls of degenerative larvae.

Question 22

Angiostrongylus vasorum

Answer 22

in dogs and foxes

molluscs are IMH

parasites of pulmonary arteries and right ventricle

adults–> chronic arteritis

larvae–> alveolar injury, thickened alveolar walls +/- granulomas

Question 23

Blastomycosis

Answer 23

granulomatous pneumonia

large numbers of small granulomas throughout lungs, many macrophages filled with small punctiform intracytoplasmic dark oval yeast bodies- big, gritty, swollen looking.

Question 24

Embolic pneumonia

Answer 24

Ruminitis (devitalization of mucosa, bacterial rumenitis, bacteria seed portal circulation)–> hepatic abscesses–> blood through caudal vena cava to lungs–> embolic pneumonia–> caudal vena cava syndrome–> rupture of pulmonary arteries, hemolysis, death.