Lecture 17: Respiratory 2 Flashcards
Define atelectasis
It is the incomplete expansion of alveoli that can affect the whole lung or just part of it
What is the gross appearance of atelectasis
dark and sunken
What are the types of atelectasis
congential
acquired
- compressive
- obstructive
What does congenital atelectasis indicate
It indicated the the neonatal lungs are not inflating
May be obstructed with meconium or amniotic fluid in the bronchi or bronchioles
If it is focal it can resolve over time
If it is diffuse it can indicate underlying problems
- acidosis/distress causing aspiration of fluid
- surfactant problems resulting in alveoli that can’t stay open (higher risk if premature
What might cause compressive atelectasis
external compression from something outside the lung in the thorax
- space occupying mass like a tumor/abccess/neoplasia
- bloat
- pyothorax
What might cause obstructive atelectasis
Blockage of airway from inside the lung
- mucus
- exudate
- aspiration
Narrowing lumen
- edema
- inflammation
Define emphysema
It is the distension and rupture of alveoli
How does emphysema present grossly
It is ‘bubbly’ and has crepitus
Due to air bubble/bullae formation in the parenchyma or connective tissue
What are the 2 types of emphysema and which occurs in animals
primary - not in animals (due to inhalation of smoke)
secondary - found in animals (secondary to disease)
What are 2 mechanisms that result in secondary emphysema
- obstruction to outflow
- bronchopneumonia because the exudate acts as a 1 way valve which allows air to enter but prevent its escape - agonal change
- normal at slaughter
- excess airway constriction from gasping against a closed airway
- more common at the edges of the lung
Define pulmonary congestion
Passive accumulation of blood in the lungs
not the same as hyperemia
What might cause pulmonary congestion
heart failure
- stagnation of blood in pulmonary vessels can result in leakage
- intra alveolar hemorrhage
gradual causes
- DIC
- vasculitis
- septicemia
- coagulopathy
sudden = erosion of the pulmonary artery = sudden hemoptysis and death
It can also be an artifact of death via jugular cutting or blunt force trauma
What is the gross features of pulmonary congestion
heavy, edematous lungs with hemorrhagic/serosanguinous fluid that oozes when cut
Define pulmonary edema
It is the accumulation of fluid in the pulmonary interstitium and alveoli
The fluid accumulation overwhelms the macrophage’s ability to resorb
- the macrophages become less effective when they are floating
fluid leak > fluid resorb (or lymph drainage)
What are 2 categories of pulmonary edema
cardiogenic/hydrostatic
permeability/inflammatory
List 4 causes of cardiogenic or hydrostatic pulmonary edema
congestive heart failure
iatrogenic fluid overload
hypoproteinemia
reduced lymph drainage or a lymph blockage
List 4 causes of permeability or inflammatory pulmonary edema
general inflammation resulting in leaky vessels
viral or toxic lung disease
acute respiratory distress syndrome (ARDS)
shock
Are necropsy findings diagnostic for ARDS? If so what findings indicate this disease?
No cant diagnose from a necropsy alone
What are the gross features of pulmonary edema
lots of froth in the trachea (only a little froth is an agonal change at death)
failure of lung to collapse
- can see the intralobular septa and rib impressions
heavy/dark/wet
- ooze serosanguinous fluid
What is the histologic features of pulmonary edema
pink fluid in the alveoli
List 4 types of pulmonary embolisms and what are their features?
Thromboemboli (insignificant - fibrinolysis will degrade)
septic or bacterial emboli (from vegetative valvular endocarditis resulting in embolic pneumonia and abcess/hemorrhage)
fat emboli from bone fractures
tumor emboli (common)
How common is pulmonary neoplasia? What is a unique feature that occurs when neoplasia occurs in the lungs?
primary neoplasia is rare
secondary neoplasia is common
space occupying mass = hypertrophic osteopathy (symmetrical periosteal proliferation)
An animal comes in with a lung lobe torsion. What animals is it most likely to be? What are the gross lesions?
deep chested dogs - usually the right middle lobe
can affect any species though
It causes pulmonary infarct and coagulation necrosis
What causes lung lobe torsion
idiopathic
What are the clinical signs of lung lobe torsion
if it is sterile (without bacteria) the body will wall it off and there will be very minimal clinical signs
if there is bacteria is it bad and can rupture to form a pyothorax
List 4 causes of pulmonary mineralization
kidney failure and uremia
hypervitaminosis D
- rodenticide
- calcinogenic plant (solanum)
multifocal osseus metaplasia = incidental change of aging
barbiturate euthanasia
What is the cause of smooth dark pigmented lung surface?
pulmonary melanosis
It is incidental
What animals commonly have pulmonary melanosis
pigs, sheep, horses, goats
in the lung, GI, meninges
What is pneumonia?
any inflammatory lesion
What does the BIGE stand for
pneumonia classifications
bronchopneumonia
interstitial pneumonia
granulomatous pneumonia
embolic pneumonia
What are 2 types of bronchopneumonia and their gross features
suppurative and fibrinous
both are usually a cranioventral distribution
suppurative causes a firm texture while fibrinous causes a hard texture
it is firm and dark like atelectasis
What ‘portal of entry’ is primarily responsible for bronchopneumonia
aerosol
resulting in inflammation around the airways
What is the distribution of interstitial pneumonia in the lungs and the gross features
diffuse due to inflammation of alveolar interstitium
Causes an elastic texture with rib imprints on the ‘up’ side
firm/meaty
fail to collapse
What ‘portal of entry’ is primarily responsible for interstitial pneumonia
Not aerosol becaues it is not centered around the airways
mny causes
virus
toxin
allergen - antigen/Ig complex
sepsis/DIC = endothelial damage
suffocation (reduced oxygen)
What is the pattern of distribution of granulomatous and embolic pneumonia?
multifocal (usually around blood vessels) nodules
either due to granulomatous inflammation throughout the lung or
inflammation in the pulmonary arterioles and capillaries (embolic)
What ‘portal of entry’ is primarily responsible for granulomatous pneumonia
aerosol or blood
What ‘portal of entry’ is primarily responsible for embolic pneumonia
blood
emboli
- valvular endocarditis
- hepatic abscess
sepsis
IV catheter contamination
omphalophlebitis
Define hypostatic congestion
Passive congestion of the lungs that occurs when the animal has dies and is laying on the same side for a long time
- blood drains to the ‘down’ side
What are the 4 sequelae of bronchopneumonia
pleural adhesions
lung abscess
- contain purulent material (can progress to caseous)
bonchiectasis
- occur due to a prior bronchopneumonia not a current one
lung sequestrum
- less common
- similar to abscess but much larger: large section of necrotic lung separated by connective tissue
What is bronchiectasis
It is the most common sequelae of bronchopneumonia
It forms from the rupture and dilation of the bronchial wall due to enzymes resulting in distended bronchioles
This is irreversible collateral inflammation damage
What are the gross and histologic features of bronchiectasis
It is similar to lung abscess
- full of neutrophilic purulent exudate in the airways
Histo can differentiate abscess and bronchiectasis
abcess = fibrous capsule
bronchiectasis = bronchial cartilage surrounding
Compare fibrous and fibrinous bronchopneumonia
fibrous adhesions = indicated there was a prior pneumonia
- not easy to peel, has dark red/firm lung around it
fibrinous = yellow/easy to peel/acute
- indicated active fibrinous bronchopneumonia
What comprises lung intersititum
endothelium
basement membrane
connective tissue
How is interstitial pneumonia diagnosed
histology required
What are 3 categories of causes of granulomatous pneumonia? Give examples.
phagocytic resistant bacteria - mycobacteria or rhodococcus
systemic fungal infection
- blastomyces
- coccidiodes
- histoplasma
- cryptococcus
FIP (forms granulomas around blood vessels in the lung, brain, and eyes)
How to differentiate between granulomatous and embolic pneumonia
histology required
in the early stages of embolic it causes hemorrhage randomly distributed throughout the lung
What is the primary consequence of effusive lung conditions
atelectasis
List 5 types of pulmonary effusive conditions and their gross appearance
hydrothorax - clear fluid
pyothorax - sticks to the surface of organs and cloudy +/- colour
hemothorax - clots in thorax along with an atelectatic lung
chylothorax - white fluid that does not adhere to surfaces + clear and shiny serosal surfaces
pneumothorax - both lungs are collapsed
On necropsy you find the thorax full of red fluid with no clots present. What is the most likely cause?
pyothorax
clots are required to diagnose hemothorax
Define pleuritis
inflammation of the pleura
it is very painful
What are the types of pleuritis
named based on the type of exudate
- fibrinous
- granulomatous
-hemorrhageic
- suppurative (due to pyothorax exudate)
What is a common sequelae of pleuritis
fibrinous or fibrous adhesions
What causes pleuritis
it can involve only the pleura due to hematogenous bacteria or it can be from a pneumonia (mannheimia hemolytica)
Name a pleural neoplasia
mesothelioma
