Tracheobronchial Disease Flashcards
What structures are typically affected with tracheobronchial disease
Nasopharynx
Trachea
Bronchi
Bronchioles
these are the conducting airways- not for gas exchange but important to warm, humidify, and filter the air
What are the purposes of the conducting airways like the nasopharynx, trachea, bronchi, bronchioles
these are the conducting airways- not for gas exchange but important to warm, humidify, and filter the air
What are the 3 main cell types in the trachea
1) Pseudostratified Ciliated- move mucus to mouth so we can swallow it
2) Goblet cells
3) Basal cells - stem cells- regenerate epithelial lining
What are the defenses that the conducting airway system has
1) Epithelial barrier: physical barrier
2) Mucus- to trap in particles
3) Mucociliary elevator- moves mucus outwards to then be swallowed
4) Oxidant defenses
5) IgA antibodies
6) Lysozymes, defensins, mucins, NO (not pathogen specific)
In the conducting airways, what are typical responses to insults
1) Epithelial cell desquamation- stripped away
2) Goblet cell hyperplasia
3) Increased mucus production
4) inflammation and bronchoconstriction
Why do patients need to cough
epithelial cell desquamation, losing the ciliated epithelium
goblet cell hyperplasia with increased mucus production
bronchoconstriction
need to cough to force mucus out
What are the consequences of insult to the conducting airways
ex: virus leaves no defense system (ie mucociliary system)
susceptible to secondary infection: opportunistic bacteria in the lower airways
parenchymal infection occurs (pneumonia)
What are the clinical signs of tracheobronchial disease
-hacking cough
-stridor
-wheezes
-inspiratory, expiratory effort
-airway obstruction
-dyspnea
What are the two big causes of a cough
1) Cardiac
2) Respiratory- conducting or respiratory zones
What evidence might tell you that a cough is from cardiac disease
Murmur
Arrhythmia
Abnormal Pulse Quality
Abnormal perfusion
Parameters
Collapse
Respiratory disease can be from disease in what zones
Conducting zone
-Nasopharynx
-Trachea
-Bronchi
-Bronchioles
-Smooth Muscle
Respiratory Zones
-Respiratory Bronchioles
-Alveolar ducts, sacs
-alveoli
-interstitium
What are the clinical signs of disease in the respiratory zone
-Respiratory Bronchioles
-Alveolar ducts, sacs
-alveoli
-interstitium
-Cough
-Dull Moist crackles
-Dyspnea
-Restrictive pattern
-Systemic illness
-Fever *
-Hypoxemia
What are the clinical signs of disease in the conducting zone
-Nasopharynx
-Trachea
-Bronchi
-Bronchioles
-Smooth Muscle
-Stertor or Stridor
-Dry, elicited, honking
-Wheezes
-Clear BV sounds
-Obstructive pattern
-Normoxemia
How do the sounds differ between conducting zone disease vs respiratory
Conducting: stertor or stridor, dry, elicited, honking, wheezes
Clear BV sounds
Respiratory: cough, moist, crackles, dull
What are typical etiologies of conducting zone disease
Vascular (bleeding, clotting, BP) : hemorrhage
Infectious: viral, bacterial, fungal, parasitic, protozoal
Toxin/Trauma: inhaled toxin, crushing
Anatomic: inhaled FB, tracheal stenosis
Metabolic: ?
Inflammatory: allergic airway disease, GE reflux
Neoplasic: airway mass
Degenerative: tracheobronchial malacia
What are viral causes in a dog with a conducting zone cough
1) Distemper (CZ +RZ)
2) Influenza (CZ + RZ)
3) CIRDC (CZ+/- RZ)
-canine adenovirus type 2
-canine parainfluenza virus
-canine respiratory coronavirus
-Canine influenza (H3N2, H3N8)
-Canine herpes virus
-Canine distemper virus
What are bacterial causes of a dog with conducting zone cough
1) Mycoplasma
2) Hematogenois pneumonia (RZ)
3) Secondary bacterial infection after viral illness (RZ)
What are fungal causes in a dog with a conducting zone cough
Blastomycosis (RZ)
Coccidiomycosis (RZ)
What are fungal causes in a dog with a conducting zone cough
aberrant larval migration (RZ)
lung worms
What are the 6 agents in the CIRDC
1) canine adenovirus type 2
2) canine parainfluenza virus
3) canine respiratory coronavirus
4) Canine influenza (H3N2, H3N8)
5) Canine herpes virus
6) Canine distemper virus
leads to a secondary infection
Today, what are the two most common CIRDC causes
Canine influenza and herpes virus today
use to be: adenovirus type 2 and parainfluenza
What is the pathophysiology of CIRDC
1) Adherence to respiratory epithelium and cilia
2) Infection of epithelial cells, necrosis and loss
3) Destruction and loss of cilia
4) Increase mucus production
5) Stimulate immune cell influx
without these defense systems, secondary bacterial infection occurs to come in and impact the mycoplasma
What are common secondary bacteria that occur after primary CIRDC infection
Mycoplasma cynos
Bordatella bronchispetica
Strep. equi subs zoo epi.
other secondary opportinistics
How are contagious viral pathogens typically spread
Aerosol spread
What is the incubation of viral respiratory pathogens
Typically 2-10 days
What factors increase risk for respiratory pathogens
1) Crowding
2) Poor ventilation, sanitation
3) Frequent intro of new animals
4) Stressed animals
5) Lack of vaccination
What are the CIRDC clinical signs
Asymptomatic
Acute
Dry, hacking cough
sneeze
serous nasal discharge
serous ocular discharge
(transition zone)
What factors contribute to the severity of CIRDC
-Secondary infection
-pathogen
-age (young)
-co-infection
-vax status
What are the clinical signs of CIRDC with secondary infection
systemically ill
febrile
moist, productive cough
respiratory distress
hypoxemia
What are diagnostics you can do for CIRDC
-thorough history
-physical exam
+/- CBC, chemistry, UA
+/- thoracic radiographs
others: infection respiratory panels, airway sampling, CT
What might prompt you to do further investigation of CIRDC
-severe or rapidly progressive clinical signs
-suspected secondary pneumonia
-symptoms persist longer than 7 to 10 days
-shelter outbreaks
-pattern of endemic respiratory disease
-necropsy
What is a canine respiratory screen
culture, molecular diagnostics assays that take 1-2 weeks for results
samples: nasal swab, TTW, necropsy tissues
screens for multiple respiratory pathogens
not reasonable for critically ill patients due to the long amount of time it takes for the results
What are some limitations of canine respiratory screen
-pathogen may not be present at the sampling site
-commensal overgrowth
-oathgen may be diffucult to cultivate
-antimicrobials may hinder
-acute illness may precede antibody production
-vaccination
-previous exposure doesnt prove disease
-only detects pathogens on panel
-MLV may cause positives
-viral shedding may end before sample collection
How might you achieve airway sampling
1) Transoral wash
2) Transtracheal wash
3) BAL
Do animals need to have anesthesia for transoral wash
Yes
Do animals need to have anesthesia for transtracheal wash
No - can be awake
What is a downside to transoral wash
1) It is non-specific
really need diffuse lung disease because you dont know where the saline reaches
2) Under anesthesia- cannot cough
Why are transtracheal washes better than transoral
You also have the downside of it being non-specific (you dont know where youre sampling from), however, the animal is awake and can cough
What is the pros and cons of BAL
can visualize the disease via scope and the sampling is specific
cons: need anesthesia, dangerous when extubate, and expensive
What is the normal composition of airway cytology
1) Alveolar macrophages (90%)
2) Small lymphocytes 5-14%
3) Eosinophils 5% (cats 25%)
4) Neutrophils <5-10%
5) Mast cells <2%
*numbers change based on what disease process is going on
In addition to your inflammatory cells, what else should you look for on airway cytology
Ciliated epithelium
Goblet cells
tells you that it came from the airway
What are the different types of results you can get for airway cytology
1) Non-septic suppurative
2) Septic suppurative
3) Eosinophilic
4) Neoplastic
5) Hemorrhagic
What is the process of the cough reflex
1) Stimuli on the larynx, trachea, bronchi
2) Vagal nerves (afferent limb) reaches the cough centre in the medulla oblongata
3) Efferent motor nerves reach the laryngeal and respiratory muscles
4) Cough
How long should you isolate CIRDC dogs
2 weeks after the cough stops
What are examples of cough suppressants
1) Hydrocodone
2) Butorphanol
3) Codeine
4) Dextromethorphan
What are the downsides of using cough suppressants
you dont want him not coughing because then hes at a higher risk of pneumonia however they are important so the dog sleeps
good idea for overnight
opioid agoinst that suppresses cough reflex in the medullary cough center
has drying effect to respiratory mucosa
best for oral cough suppression
Hydrocodone
What should you be aware of when using hydrocodone for cough suppression
1) Combo drugs in the store- dont want tylenol or others
2) controlled drug
you should limit use of hydrocodone for cough suppression to
overnight use
it has drying effect to respiratory mucosa
What is the downside to using butorphanol for cough suppression
poor oral bioavailability
doses need to be really high
good for injection in hospital
a kappa agonist, mu antagonist that has poor oral bioavailability so its use for cough suppression should be limited to hospital injection
Butorphanol
an NMDA-receptor agonist that reduces cough receptor sensitivity
poor oral bioavailability, short half life
dextromethorphan
For conducting airway disease, when do you consider antibiotics
1) Evidence of bacterial infections
-Fever
-Mucopurulent discharge
-Wet cough
-Lethargy
-Inappetance
-Pneumonia on radiographs
2) Young patients or immunosuppressed patients
What are good empiric antibiotic options for dogs with conducting airway disease
1) Doxycycline - suspected primary infection with B. bronchiseptica or M. cynos
no evidence of secondary pneumonia
7-10 day course
2) Clavamox- treatment of secondary bacterial pneumonia
Clavamox is ineffective against what respiratory pathogens
Mycoplasma
Bordatella resistance
Clavamox is used for treatment of
secondary bacterial pneumonia
Ineffective against mycoplasma, and has bordatella resistance
Doxycycline is for suspected primary infection with
B. bronchiseptica or M .cynos
and no evidence of secondary pneumonia
do 7-10 day course
What is the risk of Doxycycline in young animals ***
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