Lecture 18: Respiratory 3 Flashcards
What are the steps to diagnosing pneumonias
- ensure it is lung disease
- differentiate from agonal breathing before death, anemia, or acidosis
- legs may be in a basewide stance in increase respiratory ability - examine the lung
- necropsy or biopsy
- TTW/BAL
- rad/CT/MRI
- hemogram/biochem/culture + sens/blood gas
List 7 main causes of pneumonia. Give examples.
viral (many - herpes common)
bacterial (mycoplasma/mannheimia/pasturella/tuburculosis)
fungi (opportunistic - aspergillus or systemic)
toxin (uncommon - increase risk of bacterial infection)
parasite (lungworm)
allergy (feline asthma syndrome or allergic bronchitis/RAO)
other - aspiration
Define complex/enzootic pneumonia
viral infection followed by a bacterial infection causing pneumonia
What is another name for bovine respiratory disease complex? What animals does it mainly effect?
shipping fever
3d-3weeks after cattle arrive to feedlots
What causes BRDC
multifactorial
enviro + host + pathogen factors
- stress
- immunity
- temp
- humidity
- metabolic acidosis (from diet)
- many pathogens
Explain the 2 hit theory and provide examples
- viral infection
- bovine respiratory syncytial virus
- bovine parainfluenza virus
- infectious bovine rhinotracheitis (herpesvirus 1) - secondary bacterial infection from opportunistic pathogen
- mannheimia haemolyticum
- pasturella multocida/histophilus somni/mycoplasma bovis
this results in bronchopneumonia with/or without fibrin
What animals are targeted by enzootic pneumonia of calves? What causes it?
<6mo calves (dairy > beef)
multifactorial
- nutrition
- ventilation
- density
- failure of passive immunity transfer
- many agents via the 2 hit theory
What is the gross lesion associated with enzootic pneumonia of calves
bronchopneumonia
What is the pathogenic mechanism of bovine respiratory syncytial virus
It impair alveolar macrophage function resulting in increased risk for secondary infection
What is the gross lesion resulting from bovine respiratory syncytial virus
bronchinterstitial pneumonia
cranioventrally it is deep red atelectasis and rubbery
caudodorsally it is voluminous, heavy, and fails to collapse
require histo to dx
What is a common differential for bovine respiratory syncytial virus and why?
bovine parainfluenza virus 3
because they both have bronchoalveolar epithelial syncytia +/- intracytoplasmic eosinophilic inclusions
they are both grossly a mixed pattern of pneumonia
What is the gross lesion associated with bovine parainfluenza virus 3
broncho interstitial pneumonia
cranioventrally it is red-grey atelectasis and rubbery
caudodorsally it is emphysema
require histo to dx
What are the main histologic lesions of bovine parainfluenza virus 3
necrosis of airway epithelium
bronchiolitis/bronchitis
same bronchoalveolar epithelial syncytia +/- intracytoplasmic eosinophilic inclusions of BRSV
Where does mannheimia haemolyticum come from?
commensal in nasopharyx
What are the gross lesions associated with mannheimia haemolyticum infection
fibrinous bronchopneumonia
well demarcated necrosis on cut section
What is a characteristic feature of mannheimia haemolyticum in histology
oat cells
- lysed neutrophils
lysing on neutrophils due to leukotoxin
What is a common differential for mannheimia haemolyticum
Bibersteinia trehalosi
because it also produces a leukotoxin and can produce oat cells
Where does pasturella multocida come from
commensal in nasopharynx
What are the gross features of pasturella multicida infection
bronchopneumonia classical to brdc
- dark red firm consolidated lungs
- can have fibrin and pleuritis
- well demarcated
- no coagulative necrosis
At necropsy you are presented a cow with cranioventrally well demarcated, dark, red, consolidated lungs with fibrin. What is the condition affecting the lungs called? What are 3 bacterial species that you should suspect and how to confirm which one it is?
bronchopneumonia
Pasurella multicoda
Mannheimia haemolyticum
Histophilus somni
need to culture to distinguish
Pasturella usually doesn’t have necrosis whereas Mannheimia does
Where do you get histophilus somni
commensal in upper resp
What are some common consequences of Histophilus somni infection
bronchopneumonia
pleuritis
pericarditis
polyarthritis
thromboembolic meningoencephalitis
Which pneumonia-causing bacteria lacks a cell wall
Mycoplasma
What diagnostic testing should you use if you suspect Mycoplasma
use PCR rather than culture
They are very slow growing so it makes culturing them difficult - fast results via PCR
What is an important pathological mechanism of Mycoplasma
they adhere to respiratory epithelium and cause cilia stasis
- inhibit the mucociliary apparatus
What are the common consequences/gross lesions of Mycoplasma bovis infection
caseonecrotic bronchopneumonia with abscesses
- cranioventral distribution with multifocal white raised well demarcated foci of caseous necrosis
polyarthritis
otitis media
also mastitis and secondary infection via Truperella pyogenes
it causes a more chronic infection vs other causes of BRDC
A bison is submitted for necropsy, you find bronchopneumonia and abscesses. What is a top differential?
Mycoplasma bovis
- causes severe disease in bison
What animals are targeted by Mycoplasma bovis
cattle
bison
List 3 main Mycobacterium species in vet med
tuberculosis via M. bovis or M. tuberculosis
johnes via M. avium tuberculosis
leprosy via M. lepraemurium
If you suspect Mycobacteria, how should you confirm/diagnose it
use an acid fast stain
dont use a gram stain because there is too much lipid
What is the gross presentation of Mycobacterium
tubercles in the retropharyngeal, tracheobronchial, and mediastinal* LN
- nodular mineralized granulomas
lung lesions are only in 10-30% of cases - usually in caudal lobes
What are the 3 characteristic histologic features of a tubercle from Mycobacterium
central necrosis +/- mineralization
small amounts of acid fast bacteria in tubercle/in macrophages
rim of epithelioid macrophages and multinucleated giant cells
What type of pneumonia does tuberculosis cause
granulomatous
What animals are the wildlife reservoir for tuberculosis
cervids and bison
What is something to be cautious about if you suspect tuberculosis
it is zoonotic (M. bovis is lower risk than M. tuberculosis)
federally reportable disease (mycobacteria bovis)
What does M. bovis stand for?
EITHER
Mycobacteria bovis = tuberculosis, federally reportable
or
Mycoplasma bovis = not reportable
What is the pathogenesis of fog fever and what animals does it affect?
It usually occurs in autumn 4-10 d after moving to lush pasture
- higher levels of tryptophan in lush pasture
in ruminating animals tryptophan is converted to 3-methylindole = toxin
young animals - not ruminating yet are resistant
What is another name for fog fever
acute bovine pulmonary emphysema and edema
What is a parasite that can affect the lungs of cattle? what lesions does it create?
Dictylocaulus viviparus (lungworm)
granulomatous pneumonia
What is a parasite that can affect the lungs of small ruminants? what lesions does it create?
Muellaris capillaris (lungworm)
granulomatous pneumonia
Which 2 small ruminant lentiviruses cause lung disease? What do they cause?
ovine progressive pleuropneumonia aka maedi visna
- sheep > goat
caprine arthritis and encephalitis virus
- goat > sheep
they both cause an interstitial pneumonia
- also other signs like encephalomyelitis, arthritis, mastitis
What small ruminant disease is oncogenic?
ovine pulmonary adenocarcinoma caused by jaagsieke sheep retrovirus
A sheep is brought in for necropsy, you find heavy, pale lungs with rib impressions on the up side and a rubbery texture. These lesions are primarily affecting the causal lobes. What is a top differential?
ovine progressive pleuropneumonia
interstitial pneumonia
What are the clinical signs associated with caprine arthritis and encephalitis virus
adults get arthritis and kids get encephalitis/neurologic disease
- both can get pneumonia but it is less common
What are 2 histologic features of caprine arthritis and encephalitis virus
dense eosinophilic fluid in alveoli
type 2 pneumocyte hyperplasia
What causes porcine respiratory disease complex? Give examples
multifactorial
enviro - temp/humidity/air quality
animal - stress/immune
pathogen
- virus - PRRS and PCV2 aka post weaning multisystemic wasting syndrome (also swine influenza virus)
- bacteria - Mycoplasma hypneumoniae (also Actinobacillus pleuropneumoniae, pasturella multocida)
What are the gross lesions associated with actinobacillus pleuropneumoniae? What species does it affect?
pigs
bronchopneumonia BUT with a caudal dorsal distribution (usually it is cranioventral)
What is the agent causing enzootic pneumonia of pigs? What lung lesions does it cause?
Mycoplasma hypneumoniae
bronchopneumonia
- cranioventral distribution
- rubbery firm texture
What lung lesions does PRRSV cause
procine repro and resp syndrome causes interstitial pneumonia +/- granulomas
- lung fail to collapse
- rib impressions
- firm texture
disease increases susceptibility to bacterial infection
What disesae does PCV2 cause
post weaning multisystemic wasting syndrome
What are the main consequences of PCV2 infection
lymphoid depletion and immunosuppression resulting in increased risk for bacterial infection
granulomatous bronchointersitial pneumonia
What kind of lung lesions does swine influenza cause
broncho interstitial pneumonia
- cranioventral atelectasis
- large edematous LN
Why is swine influenza concerning
because swine have cell receptors for human, avian and swine influenza types and so they can act as a mixing pot for virus recombination
What is RAO and what other disease is it similar to
recurrant airway obstruction aka heaves is equine asthma
- a reversible airway obstruction due to bronchospasm
it is similar to feline asthma
What areas of the lung is affected by RAO
small bronchioles and the caudodorsal lung
What type of pneumonia does rhodococcus equi cause
pyogranulomatous bronchopneumonia
- firm raised coalescing nodules
What animals does rhodococcus equi target
1-6 month old foals
What are 3 clinical manifestations of rhodococcus equi infection
enteritis
polyarthritis
pneumonia
What causes equine bronchopneumonia
multifactorial affecting young horses
stress
transport
general anesthesia
environment
pathogens
- strep equi equi
- pasturella multocida
- bordatella bronchiseptica
What parasite affects the lungs of horses primarily causing chronic cough? What other animals does it infect
Dictylocaulus arnfieldi (lungworm)
targets donkeys more than horses
What equine parasite causes chronic granulomas in the lungs
round worm - Parascaris equorum
nodular lung lesions due to larvae migration
What is another name for canine infectious respiratory disease complex? What causes it?
kennel cough
multifactorial
virus
- canine parainfluenza virus
- canine adenovirus 2
- canine herpes virus 1
bacteria
- bordatella bronchiseptica
vaccinate for all of above
What causes canine respiratory coronavirus
betacoronavirus
only a mild upper resp disease
What causes canine influenza and what is its significance?
H3N8 (jumped from horses to racing greyhounds)
It can worsen kennel cough
What are the consequences of canine herpes virus 1
<8 week old = death
> 8 weeks = survive
acute respiratory disease
What are the consequences of canine adenovirus 2 and how do we protect against it?
fever and a hacking cough
vaccinate against CAV2 - will also give cross immunity to CAV1 (infectious hepatitis)
What are the clinical signs of canine distemper
respiratory - bronchointerstitial pneumonia
GI
CNS/nervous
What are the gross and histologic lesions associated with canine distemper virus
patchy/diffuse tan - red, rubbery lesions below pleura at lung margins
interstitial pneumonia
histologically - cytoplasmic and intranuclear inclusions
What causes bronchopneumonia in dogs
multifactorial
lowered immune function predisposes
- viral infection
- immunosuppressive drugs
- herperadrenocorticism
- diabetes
- parvo
- environmental stress
aspiration pneumonia common in bracheocephalics
common pathogens
- B bronchiseptica
- Streptococcus and Staphylococcus
- Pasturella multocida
- E coli and Klebsiella pneumoniae
What are the gross consequences associated with B bronchiseptica
tracheobronchitis is more common than bronchopneumonia
it is commonly found as a commensal bacteria in resp system
- commonly found with mixed pathogen infections
List the 4 main agents causing systemic mycoses
blastomyces dermatitidis
coccidioides immits
cryptococcus neoformans and gatti
histoplasma capsulatum
What are the 4 main shared features of the agents causing systemic mycoses in cats and dogs
they are primary pathogens and don’t need preceding immunosuppression
they are zoonotic so you should NOT send for culture
they spread via hematogenous or inhale
they are dimorphic meaning that the environmental hyphae form is infectious and the form in the body is a yeast which is less infectious
What causes blastomycosis? Where is this common?
Blastomyces dermatitidis
Mississippi, ohio, st laurence river valley, N ON, MB, mid atlantic states
in sandy acidic soil
What type of lung lesions does blastomycosis cause
granulomatous pneumonia
If you suspect blastomycosis how should you confirm your diagnosis
NO culture
PCR
call lab for more info about how to dx safely
What is the most common systemic mycosis in cats
Cryptococcus
What are the crytococcus species causing lung disease? What type of lung disease does it cause?
C. neoformans and gatti
granulomatous pneumonia - gelatinous
What is valley fever caused by
Coccidioides
- usually C. immitis (or posadasii)
What animals does valley fever infect
all mammals
What are the gross lesions associated with valley fever
granulomatous pneumonia
What animals are affected by Histoplasmosis? What species causes disease? Where is it found?
young dogs > cats > horse
H. capsulatum
Mississippi, ohio, Missouri river valley, Ottawa, st laurence river valley
What type of gross and histologic findings are characteristic to histoplasmosis
granulomatous pneumonia
intracellular - found inside macrophages is characteristic
What parasite commonly affects the lungs of dogs? What are the associated clinical signs
Dirofilaria immitis (heartworm)
pulmonary hypertension and vascular sclerosis from the worms in the arteries
What causes feline respiratory disease complex
multifactorial
pathogens
virus
- feline viral rhinotracheitis (FHV1)
- feline calcivirus
bacteria
- chlamydia felis
- mycoplasma felis
What is feline asthma
reversible airway obstruction due to inflammation and airway collapse
What is feline bronchitis
irreversible airway obstruction due to chronic inflammation
can be caused by asthma or chronic infection
What causes feline bacterial bronchopneumonia
stress associated
opportunistic pathogens
- B. bronchiseptica
- Pasturella multocida
- Streptococcus equi zooepidemicus
- E coli (extraintestinal)
