Term
| Developmental abnormalities of the the lungs |
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Definition
-Congenital melanosis
-Agenesis of lungs
-Pul. hypoplasia
-Pul. hamartoma
-Ectopic lung tissue |
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Term
|
Definition
Masses of excess and redundant pul. tissue w. variable development of bronchi, bronchioles, alveoli and b.v.
-do not communicate w. normal bronchi |
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Term
|
Definition
-Primary uncommon (except in sheep) but where present, mostly epithelial orgin - mesenchymal rare
-Pulmonary adenoma (benign glandular origin)
-Pulmonary adenocarcinoma (malignant gland. origin)
-Bronchioloalveolar carcinoma (malignant epithelial orgin)
e.g Ovine pul. carcinoma / Jaagsiekta (malignant epithelial origin) |
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Term
| How may pul. adenocarcinomas spread? |
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Definition
-intrapul. spread is common
-metastases to other sites can occur
e.g. digits in cats |
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Term
| Where do bronchioalveolar tumours arise from? |
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Definition
| Clara cells or type II alveolar epithelial cells |
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Term
| Ovine pulmonary carcinoma |
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Definition
Jaagsiekta
Pulmonary adenomatosis i.e. development of multiple overgrowths
-Bronchioloalveolar carcinoma (malignant epithelial orgin)
-Of cuboidal or columnar cells resembling type II pneumocytes
-Retro-virus induced |
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Term
|
Definition
Incomplete distension of the lung
Collapsed alveoli spaces |
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Term
| Clinical signs of Jaagsiekta / Ovine Pul. carcinoma |
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Definition
-gradual loss of condition
-coughing
-resp. distress
-copious mucous fluid -pours from nostrils in "wheelbarrow test" |
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Term
| Secondary tumours of the lungs |
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Definition
Metatstatic spread of tumours to the lungs is common. e.g. from:
-mammary tumours
-haemangiosarcomas (esp. R atrial in dogs)
-osteosarcoma
-mal. melanoma
-thyroid carcinoma in cats |
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Term
| What can cause atelectasis, w. examples? |
|
Definition
-Airway obstruction - internal obstruction e.g.exudate, parasites, FB or ext. compression e.g. tumour mass
-Compression- intrapulmonary e.g. tumour mass or extrapul. e.g. pleural effusion, recumbency, mild pneumothorax
-Massive atelectasis - in cases of severe pneumothorax
-Congenital
e.g. incomplete expansion of air spaces after birth, defective surfactant production |
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Term
|
Definition
| Excessive inflation of alveoli |
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Term
| What are the types of emphysema? |
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Definition
-Alveolar emphysema
-Interstitial emphysema
-Bullous emphysema |
|
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Term
|
Definition
| Alveolar enlargement w. destruction/ rupture of alveolar walls - alveoli may coalesce and form bulla |
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Term
|
Definition
-When airways have ruptured and trapped air enters interstitial tissues
- air tends to track into interlobular septa causing expansion of septa and extends into sub-pleura |
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Term
| When is interstitial emphysema commonly seen? |
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Definition
Mostly in cattle (prob. due to poor collateral ventilation)
NB: can be common incidental finding at PM in cattle that have forced resp. efforts due to non-resp. condition e.g. recumbency |
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Term
| Describe bullous emphysema |
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Definition
| Contiguous emphysematous airspaces may coalesce to form larger air pockets known as bullae |
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Term
| Name 2 dz associated with emphysema |
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Definition
-Recurrent Airway Obstruction (RAO) in horses
-Fog fever |
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Term
| What are the causes of emphysema? |
|
Definition
Factors which cause collapse of airways on expiration and so trapping air in alveoli:
-Obstructive airway disease
-Forced expiratory efforts |
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Term
| What is the functional significance of alveolar emphysema? |
|
Definition
-Early airway collapse and trapping of air --> inc. dead space
-Destruction of alveolar walls --> reduced alv. perfusion and gaseous exchange
-Fibrosis --> reduced compliance and so incr. exp. effort - lungs stiffer |
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Term
|
Definition
Accumulation of air within the pleura
(often at lung apex) |
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Term
|
Definition
| Air filled spaces in the lungs resulting from destruction and contiguous alveloi |
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Term
| What is the consequence of rupturing a pulmonary bleb or bullae? |
|
Definition
|
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Term
| Name possible circulatory disturbances of the lungs |
|
Definition
-Hyperaemia and congestion
-Oedeam
-Haemorrhage
-Hypertension
-Emboli, thombi, infarction |
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Term
| Why do the alveoli not normally get flooded with intersitial fluid? |
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Definition
-less permeable to solutes than capillary endothelium
-epithelial cells have a sodium pump that results in fluid being drawn from the the alveolar space
-interstitial fluid is drained through the interstitial channels to the lymphatics |
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|
Term
| Under which 2 circumstances will pul. oedema occur? |
|
Definition
-Alveolar epithelium is damaged
-Excessive intersitial fluid caused by increased production or decreased drainage of fluid |
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Term
| Pul. oedema can occur due to excess interstial fluid caused by increased production or decreased drianage. What are the potential mechanisms involved? |
|
Definition
-Increased hydrostatic pressure
e.g.inflam, passive congestion (H failure), vol. overload (renal failure, over infusion)
-Increased endothelial permability
e.g. inf. agents, toxing, inflam, anaphylaxis
-Decreased colloid osmotic pressure
e.g.hypoproteinaemia (renal, hepatic, intestinal dz.), overinfusion
-Decreased lymphatic drainage
e.g. neoplasia, inflam |
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Term
| Describe pul. oedema grossly |
|
Definition
Grossly:
-lungs heavy
-may not fully collapse when thorax opened
-interlobular septa may appear enlarged and gelatinous
-cut surfaces wet and ooze blood
-foamy fluid often present in upper airways
-incr. fluid in pleural cavity |
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Term
| Why are the lungs fairly resistant to infarction? |
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Definition
-dual vascular supply
-extensive collateral circulation |
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Term
| What can result in infarction of a whole lung lobe? |
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Definition
| Lung lobe torsion (uncommon) |
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Term
| What factors predispose to thrombosis? |
|
Definition
EMBOLISM
Also:
-parasites (heartworm Angiostrongylus vasorum)
-H. disease
-Pul. vasculitis
-Sepsis
-Bact. pneumonia
-IMHA
-DIC |
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Term
| What does the effect of pul. thrombosis or emboli depend on? |
|
Definition
-Size and extent
-Nature i.e. septic or sterile
-Presence of pre-existing pul. dz |
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Term
| Common sources of septic emboli |
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Definition
-liver abscesses e.g. pul. thromboembolism in cattle
-R heart valve bact. infection (endocarditis)
-Joint and umbilical infections
-Inf. IV catheters |
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Term
| What can a massive pul. thromboembolism result in? |
|
Definition
-pul. infarction
-hypoxia
-incr. pul. resistance due to obstruction of vessel and hypoxia-induced pul. vasoconstricton
-acute cor pulmonale (hypertrophy of R vent due to pul. hypertension) -->dilation of pul. aa. and R cardiac chambers -->cardiogenic shock and death |
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Term
| What are the consequences of a small sterile pul. thromboembolism? |
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Definition
If lung healthy:
-intra-alveolar haemorr. (no necrosis) w. thrombolysis and resolution in 2-4 days i.e. no clin signs
-If lung already compromised - haemorr. and alveolar necrosis, resulting in organisation and scar tissue formation |
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Term
| What are the consequences of a small septic pul. thromboembolism? |
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Definition
In addition to haemorr. and necrosis seen w. a sterile thromboemb. in compromised lungs, septic emboli may lead to:
-vasculitis
-thrombosis
-aneurysm formation at site
-spread of inf. to adjacent tissues
-embolic pneumonia and abscess formation |
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Term
| Pul. thromboembolism in cattle |
|
Definition
-hepatic abscesses erode through the vena cava wall and form septic thrombosis
-septic thromboemboli break off and spread to the lungs
-can cause pul. arteritis, thrombosis, aneurysm, abscess
-if aneurysm ruptures = intrapul. haemorr.
-abscesses can erode through walls of pul. vessels and airways = massive pul. haemorr. into airways and epistaxis
-can result in sudden death due to rapid blood loss |
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|
Term
| Exercise Induced Pulmonary Haemorrhage (EIPH) |
|
Definition
-Very commonly seen in race horses - occasionaly fatal
-Cause is poorly understood, possibly increased BP in exericse / shock wave trauma
-Other resp. dz. can predispose to EIPH |
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Term
| Causes of pul. hypertension |
|
Definition
-increased P of blood arriving in the pul. artery
e.g. CV L-R shunts, VSDs, PDA
-increased R to blood flow through the lungs
e.g. hypoxic vasoconstriction of pul. arterioles, pul. vasc. dz., pul. fibrosis
-decreased outflow of blood through the lungs
e.g. L sided H failure |
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Term
| What changes does pul. hypertension lead to in pul b.v.? |
|
Definition
-acute fibrinoid necrosis
-chronic thickening of vasc. walls by endothelial hyperplasia, hypertrophy of tunica muscularis and fibrosis |
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Term
| Name the 4 broad morphological classifications in pneumonia |
|
Definition
-Bronchopneumonia (most common)
-Interstitial pneuomonia
-Embolic pneumonia
-Granulomatous pneumonia |
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|
Term
| What is the route of entry for bronchompneuomia? |
|
Definition
|
|
Term
| Causes of bronchopneumonia |
|
Definition
-bacteria, occ. fungi
-aspirated food or gastric contents
-impairment of pul. defences will predispose |
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|
Term
| Predominant distribution of bronchopneumonia? |
|
Definition
|
|
Term
| Describe gross appearance of bronchopneumonia |
|
Definition
-dark red - pink-greyish
-firm-hard (consolidation)
-moist, firm cut surfaces
-exudate may be expressed |
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|
Term
| Describe the pathogenesis of bronchopneumonia |
|
Definition
-infection/injury at the region of the bronchioalveolar junction by inhaled agents, results in inflam
-acute inflam response - exudation of fluid and plasma proteins into the bronchioles and alveoli and recruitment of alveolar macro. and emigration of neutrophils
-severe inf. and inflam can result in injury and necrosis of lung parenchyma and facilitate spread through interlobular septa into adjacent alveoli
-recruitment of alvelolar macrophages and emigration of neutrophils
-Inf./inflam spreads to adjacent alveoli and then along airways to other lobules, bronchioles and bronchi
-Severe inf/inflam can result in injury and necrosis of the lung parenchyma and facilitate spread through the interlobular septa |
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|
Term
| 2 subdivisions of bronchopneumonia |
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Definition
| Suppurative and fibrinous - based on type of exudate, which reflects the severity |
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Term
| Suppurative bronchopneuomia |
|
Definition
-Purulent / mucopurulent (many neutrophils)
-Confined within lobules
-Caused by a variety of bact. e.g. Pasteurella multocida, Bordetella bronchiseptica, Streps, Staphs, E.coli
-Also caused by aspiration of bland material
NB: it is the severity of injury that indicates type of bronchopneumonia, not specific agents |
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|
Term
| Fibrinous bronchopneumonia |
|
Definition
-Fibrin, oedema, neutrophils, necrosis
-Spreads rapidly within and between lobules - often affects large confluent areas/whole lobes
-Caused by a variety of bact. e.g. Mann. haemolytica, Actinobacillus pleuropneumoniae
-Also caused by inspiration of highly irritant material
NB: it is the severity of injury that indicates type of bronchopneumonia, not specific agents |
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Term
| Enzootic pneumonia in pigs |
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Definition
-Type of suppurative bronchopneumonia (v. common)
-Caused by inhalation of Mycoplasmas - adhere to and damages cilia, inducing ciliostasis which permits colonization of the airways
-promotes 2ndary bact. inf. resulting in severe sup. bronchopneumonia |
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Term
| Bovine pneuominic mannheimiosis (shipping fever) |
|
Definition
-Type of acute fibrinous bronchopneumonia in calves
-caused by Mannheimia haemolytica
-Freq. associated with recent stressors and impaired defences hence M. haemolytica can colonies tract
-M. haemolytica produces leucotoxin which causes lysis of alv. macro. and neutrophils
-release of lysososmal contents causes tissue necrosis and fibrinous bronchopneumonia w. extensive fibrin deposition in interlobular septa
-animals often die from pneumonia and toxaemia |
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Term
| Possible sequela to bronchopneumonia |
|
Definition
-Resolution over 3-4weeks
-Progression to chronic
-Atelectasis or emphysema
-Bronchiolitis obliterans
-Bronchiectasis
-Abscess formation
-pleuritis / pericarditis (inflam may extend esp. in fibrinous form)
-Death |
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|
Term
|
Definition
| Inflam associated with the alveoli walls and interlobular septae, usually as a result of (diffuse) injury to the alveolar epithelium or capillary endothelium |
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|
Term
| What is the route of entry for interstitial pneuomia? |
|
Definition
|
|
Term
| Cause of interstitial pneuomia? |
|
Definition
-Viruses e.g. parainfluenza virus 3, distemper virus
-Toxins e.g. tryptophan in grass (fog fever), paraquat, uraemia
-Inhaled agents e.g. smoke
-Allergic response
-Septicaemia
-Migrating parasites |
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|
Term
| Predominant distribution of interstitial pneumonia? |
|
Definition
|
|
Term
| Describe gross appearance of interstitial pneumonia |
|
Definition
-often appear rel. normal
-heavy
-elastic / rubbery
-red, grey, mottled
-lack of pronouced exudate
-failure to collapse when thorax opened
-may have retained costal impressions |
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|
Term
| Describe the pathogenesis of acute interstitial pneuomia |
|
Definition
INJURY-injury to type I pneumocytes or cap. endothelial cells
EXUDATIVE-expansion of the interstitial tissue by oedema and an inflam exudate (containing plasma proteins and neutro. and macro)
-Leakage of fluid and plasma proteins into the alveoli space
-May see hyaline membrane formation
PROLIFERATION -Macro. population expands to phagocytose and remove the exudate
-Type II pneuomocytes prolif. and line the alveoli to replace the lost type I cells
-If cause of inflam is removed, type II pneoumocytes differentiate into type I i.e. restored to normal |
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|
Term
| Chronic interstitial pneumonia |
|
Definition
If the injury can not be removed
-persistance of type II pneumoncytes
-accumulation of chronic inflam cells (macro., LCs, PCs)
-interstial fibrosis - fibrosis of alveolar septum or organisation of exudates in alveolar spaces |
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|
Term
|
Definition
-following ingestion of L-tryptophan in grass which is converted to a toxic metabolite
-damages type I pneumocytes
-results in acute interstitial pneumonia |
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|
Term
| Bronchointerstitial pneumonia |
|
Definition
-inf. agent injures both bronchial and alveolar epithelium and so features of both broncho- and interstitial pneumonia
-typically primary inf. results in inflam and features of acute suppurative bronchopneumonia (i.e. bronchiolar and alveolar oedema w. neutrophil exudate) and acute interstitial pneumonia (hyaline membranes, prolif. of macrop. and type II pneumocytes)
-freq. results in 2ndry bact. inf. which results in progression to predom. bronchopneumonia pattern |
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|
Term
| What is a good morpholical marker for interstitial pneumonia? |
|
Definition
| Hyaline membranes - composed of surfactant and plasma protein components |
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|
Term
| Typical causes of embolic pneumonia |
|
Definition
-Septic emboli
-Hepatic abscesses
-Heart valve infection (endocarditits), esp R
-Joint and umbilical inf. |
|
|
Term
| Gross appearance of embolic pneumonia |
|
Definition
-early lesions - cream-grey, firm, nodular foci surrounded by red halo of haemorr. / congestion
-these foci expand and form pul. abscesses |
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|
Term
| Possible sequela to embolic pneumonia |
|
Definition
-fibrosis and resolution
-chronic suppurative pneumonia
-pleuritis
-rupture of abscess = pyothorax/ pneuomthorax (if rupture connects w. alveoli) |
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|
Term
| What can result in pul. abscesses? |
|
Definition
-embolic pneumonia
-focal residues of bronchopneumonia
-aspiration of foreign material
-traumatic penetration of the lung |
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|
Term
|
Definition
| -Caused by agents that generally persist in tissues and are resistant to phagocytosis and the acute inflam response |
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|
Term
| Possible causes of granulomatous pneumonia |
|
Definition
(remember agents that are resistant to phagocytosis)
-Bact e.g. Mycobacterium (TB), Actinobacillus spp., Actinomyces
-Parasites e.g. lungworm
-Viral infections e.g. FIP
-Foreign bodies |
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|
Term
| Route of entry of granulomatous pneumonia |
|
Definition
|
|
Term
| Distribution of granulomatous pneumomia |
|
Definition
| Can be random, nodular foci, can be widespread, disseminated nodular foci |
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|
Term
| Describe the gross appearance of granulomatous pneumomia |
|
Definition
Granulomatous = lots of macrophages, some neutrophils
-firm-hard, may have discrete nodules
-might be caseous
-fibrosis may be present |
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|
Term
| Possible sequela to granulomatous pneumomia |
|
Definition
-dissemination of agent to other parts of the lung and other organs
-persistent chronic pneumonia
-fibrosis |
|
|
Term
|
Definition
-Type of granulomatous pneumonia caused by Mycobacterium spp.
-Generally inhaled and then phagocytosis by macro.
-If not killed by macrophages then will multiply IC and spreads within the lungs and to the trachiobronchial LNs via lymphatics
-get small granulomas, which enlarge and coalesce to produce large areas of caseous necrosis |
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|
Term
| Describe the morphology of TB in cattle |
|
Definition
-early changes are small granulomas, oft. in dorsocaudal and subpleural lung regions
-over time these coalesce and produce large areas of caseous necrosis surrounded by giant cells, macrop., LCs, PCs and fibrosis |
|
|
Term
|
Definition
pul. inf. results from haematogenous spread after oral exposure
-lesions may be present in other organs e.g. liver and spleen |
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