Disease of the Pulmonary Parenchyma Flashcards
What are the general clinical signs of pulmonary parenchymal disease?
- cough
- exercise intolerance
- tachypnea
- excessive panting
- increased respiratory effort/ distress (mixed inspiration/ expiration effort)
What are the clinical signs generally associated with upper airway obstruction or pleural space disease?
- increased inspiratory effort
What are the clinical signs generally associated with lower airway/ bronchial disorders?
- increased expiratory effort
What is a potential rapid test to determine cardiogenic vs pulmonary cause of respiratory distress?
NT-pro-BNP
- BNP = brain natriuretic protein
- release when there is volume overload (ex. pulmonary hypertension, esp with cardiac dysfunction and failure
- antagonizes renin-angiotensin, promotes vasodilation, and increases diuresis through the kidneys
- could be one way to rapidly diagnose between cardiac or pulmonary cause respiratory distress (higher in cardiogenic cases)
- in cats, can use pleural fluids –> but also elevated with increased creatinine - can be difficult in patients with azotemia
- overall, still cannot completely replace other diagnostics, such as imaging
What’s the limitation of the tracheal lavage?
- may be negative if the disease is deeper down in the lungs in a patient with non-productive cough
- in those cases, a bronchioalveolar lavage would be more beneficial
What’s the limitation of pulmonary FNA?
- better if there is a discrete/ focal/ consolidated mass/ region
- not helpful if diffuse –> biopsy would be more useful (ex. pulmonary fibrosis)
What are some ddx for pulmonary parasites?
- eosinophilic pneumonia
- asthma
- bronchopneumonia
- pulmonary granulomatosis
- pulmonary neoplasia
What are some examples of pulmonary parasites?
- hookworms (ancylostoma) - young puppies
- lungworms (migrates from GI system)
- usual treatment = fenbendazole or ivermectin
What are some examples of pulmonary parenchymal parasites?
- lung fluke: bullae on rads. Coughing. crayfish ingestion
- filaroides: bronchoinsterstial to alveolar pattern. Coughing, respiratory distress. fecal-oral
What are some examples of airway parasites?
- feline lungworm (A. abstrusus), mimics feline asthma
- C. vupis, nematode, in dogs only
- O. osleri, can lead to secondary bacterial infection
- E. aerophilus, nematode, worldwide
- Troglostrongylus spp., also infects wild cats
What are some other parasites relevant to the lungs?
- heartworm (D. immitis)
- French heartworm (Angiostrongylus vasorum)
- ingestion of mollusk or frog
- similar to heartworm
- inflammatory response, chronic cough, general thriftiness
- bleeding diathesis
- CXR: bronchial, interstitial, and/ or peripheral alveolar lung patterns
- CT is better
What are some common bacteria that causes bacterial pneumonia?
it’s unusual for healthy adults (esp cats) to develop bacterial pneumonia - usually there is another inciting cause (other than kennel cough)
- enteric pathogens (E coli, Klebsiella)
- Pasteurella
- coagulase-positive staphylococci
- streptoccoci
- Mycoplasma spp
- bordetella bronchiseptica
What are common presentations of bacterial penumonia?
- extremes in age, immunocompromised, or other predisposing factors
- coughing, nasal discharge, exercise intolerance, respiratory distress
- anorexia, lethargy
- fever not always present
What are some typical CBC changes that could be noted in patients with bacterial pneumonia?
- neutrophilia +/- left shit, anemia, lymphopenia
- CXR: alveolar pattern, ventral distribution
- caudodorsal distribution – hematogenous spread
- need to identify pulmonary sepsis - tracheal or bronchiolar lavage
- watch for commensal bacteria in tracheal lavage
- Mycoplasma require PCR rather than just culture
- empiric treatment = inappropriate in about 1/4 of patients, almost 2/3 if had previous antibiotic therapy
What are the treatments for bacterial pneumonia?
- Antibiotics
- ideally based on culture & sensitivity results
- empirical can start with Clavamox +/- TMS; may need a flouroquinolone in severe cases
- aim for 10-14 days - O2 supplementation
- start with PaO2 < 80mm Hg or SpO2 < 94% - Fluid therapy
- dehydration makes the cilia “stuck” in the gel layer, therefore reducing the efficacy - Ancillary therapy
- Coupage
- mucolytic, ex. n-acetylcystein (NAC)
- lung lobectomy
What kinds of infection is due to Bordetella bronchiseptica?
tracheobronchitis
- releases entoxins that impairs the mucociliary escalator
- contagious, more common in dogs than cats
- can be difficult to eliminate even with the appropriate antibiotics
What kind of infection is due to steptococcus equi Subspecies Zooepidemicus?
necrotizing hemorrhagic pneumonia
- severe, sometimes fatal
- kennel setting
What kind of infection is due to Mycoplasma?
difficult to culture, PCR is needed
- likely an opportunistic bacteria
- do NOT use beta lactams as it lacks cell wall
What kinds of infection is due to Mycobacterium?
TB and non-TB type infections
- generally granulomatous, with lymphadenopathy, pleural effusions, interstitial to alveolar infiltrates
- zoonotic
- prolonged antibiotic therapy
What kind of infection is due Yersinia pestis?
Plague!
- cats, dogs appear resistant
- must be a ddx for feline pneumonia in endemic areas
- lymphadenitis –> mandibular/ cervical nodes. bubonic plague
- can then develop into pneumonia
- can FNA the affected lymph nodes to get a diagnosis
- universally fatal if pneumonia left untreated
What are some examples of viral penumonia?
Dogs:
- canine distemper
- canine influenza virus (H3N8 and H3N2)
- canine parainfluenza virus
- canine herpes virus
- canine infectious hepatitis
Cats:
- feline calicivirus
- feline herpes virus
- feline infectious peritonitis/ coronavirus
What are some clinical signs associated with the influenza virus?
dogs: H3N2 (avian), H2N8 (equine)
- cough, lethargy, fever
- highly contagious
- marked morbidity but low mortality
Cats: H5N1
- less frequent
- could be life threatening
What’s the most common protozoal pneumonia?
protozoal pneumonia is uncommon in both cats and dogs
- Toxoplasma gondii = most common one in cats
- can involve GI, respiratory, CNS, abdominal viscera, eyes, and heart
- Tx = potentiated sulfonamides or clindamycin
- often see rapid improvement, but recurrence is possible
What are some common mycotic pneumonia?
Blastomycosis, histoplasmosis, coccidiosis
- progressive, lower respiratory disease
- extrathoracic signs also possible – weight loss, anorexia, lymphadenopathy
- Tx = expensive and potentially toxic, therefore, need definitive diagnosis
- Diagnosis can be done with extrathoracic sites
Which type of mycotic infection is common in Dachshund and King Charles Cavalier?
pneumocystis carinii
- Dachshund and King Charles Cavalier
- not very highly virulent
- but in immunocomprised patient = high morbidity and mortality
- clue: absence of fever despite severe pneumonia
What are the 3 phases of aspiration pneumonia?
- acute airway response
- lung inflammation
- opportunistic bacterial infection
What are the typical radiographic signs of aspiration pnuemonia?
patchy or foal alveolar infiltrate - R middle, R cranial, and caudal portion of the L cranial
How is aspiration pneumonia treated?
Supportive therapy
- minimize risk in the first place
- H2-antagnoist or proton-pump inhibitors may help
- prokinetics may help
- if aspiration was witness, airway lavage
- monitor O2 sat, provide supplemental O2 as needed
- bronchodilator to ameliorate acute bronchospasm
- antibiotics for secondary bacterial infection
What are some clinical signs of aspiration pneumonia?
excessive panting, tachypnea; coughing, harsh/loud adventitial or reduced lung sounds
How does pulmonary edema happen?
- increased hydrostatic pressure
- reduced oncotic pressure
- impaired lymphatic drainage
- increased vascular permeability
- all leads to fluid accumulation in the interstitium then flows to the alveoli at a rate faster than its can be absorbed
- fluid in alveolus = V/Q mismatch
What’s the pathophysiology for cardiogenic pulmonary edema?
increased hydrostatic pressure due to backup of blood from the left side of the heart
- resultant alveolar edema = non protein rich
What’s the treatment for cardiogenic pulmonary edema?
- diuretics
- afterload reduction
- treat the underlying cardiac issue
What’s the pathophysiology for noncardiogenic pulmonary edema?
- increased epithelial permeability due to epithelial damage –> fluids go from blood vessels to interstitum to alveolus
- edema = protein rich
- active removal of fluid will require Na+/Cl- pump, which in damaged epithelium, also isn’t working well –> making the fluid accumulation worse
What are some predisposing factors for noncardiogenic pulmonary edema?
- neurogenic, electric shock –> intense pulmonary vasoconstriction leads to increased hydrostatic pressure, plus inflammatory mechanism
- systemic inflammation
- post-obstructive
- direct pulmonary injury
- toxins
- hypoalbuminemia (must be profound)
- impaired lymphatic drainage
- others (ex. drowning, pheochromocytoma)
What are the presenting signs for noncardiogenic pulmonary edema?
- acute or up to 72h delay
- wet, productive cough, exercise intolerance, tachypnea
- harsh, loud, bronchovesicular sounds, crackles
(if cardiogenic, would also hear heart murmur/ arrhythmia) - noncardiogenic tend to have respiratory sinus arrhythmia vs sinus tachycardia with cardiogenic edema
How can cardiogenic vs noncardiogenic pulmonary edema be differentiated?
- cardiogenic: usually have heart murmur, arrhythmia (sinus tachycardia)
- noncardiogenic: may not have heart murmur (thought concurrent heart disease is possible), arrhythmia is more a sinus arrhythmia
- lack of cardiomegaly or pulmonary vein engorgement = likely noncardiogenic
- ARDS = patchy alveolar infiltrates
How is noncardiogenic edema treated?
- correct the underlying cause if possible
- supportive therapy: reduce stress/ sedation, O2 supplementation
- avoid cerebral vasodilators
- synthetic colloids? will need a lot of it and may have adverse reaction
- mechanical ventilation
What is interstitial lung disease?
non-infectious, non-malignant respiratory tract disorder
How is interstitial lung disease diagnosed?
histopathology
Describe eosinophilic pneumonia.
Eosinophilic Pneumonia
- can see peripheral eosinophilia in some cases (about half)
- reactive eosinophilic airway disease (cats), idiopathic (dogs)
- BAL
- short course of corticosteroids; Px = fair to excellent
Describe lipid pneumonia.
Exogenous (aspiration) vs Endogenous (unassociated with aspiration) lipid pneumonia
- uncommon/ rare
- pneumocyte injury –> overproduction of cholesterol-rich surfactant. Lipids phagocytosed by macrophages –> accumulate in alveoliW
Which breeds are predisposed to idiopathic pulmonary fibrosis?
Westies and Staffordshire bull terriers
What are the clinical signs associated with idiopathic pulmonary fibrosis?
- cough, exercise intolerance (dogs)
- cats: acute respiratory distress, sudden death
- on PE: inspiratory crackles, may hear heard murmur (tricuspid regurgitation); cyanosis (dogs)
- CXR: dogs- bronchointerstitial infilfrates
- so crackles + lack of alveolar pattern = very likely pulmonary fibrosis in dogs
- pulmonary hypertension is common found
How is idiopathic pulmonary fibrosis treated?
Cats: only survive for days/ weeks
Dogs: long-term survival possible (32m) with treatment
- cough suppressant, phosphodiesterase-5 inhibitors
Which breeds are overrepresented in lung lobe torsion?
Afghan and Pugs
