Dyspnea in Small Animals: Diagnostic Approach Flashcards
what are inspiratory causes of dyspnea (6)
- nasopharyngeal mass
- stenosis
- foreign bodies
- laryngeal paralysis
- neoplasia
- tracheal mass
what are expiratory causes of dyspnea (3)
- dynamic airway collapse
- feline asthma
- pulmonary parenchymal disease (IPF; pneumonia; edema)
how is dyspnea investigated (10)
- history
- clincal features (signlament)
- physical exam (with supp oxygen)
- thoracic radiography (stable)
- thoracic and cardiac ultrasonography
- thoracocentesis
- blood/fecal tests
- rhinoscopy, laryngoscopy, bronchoscopy
- FNA of lungs
- CT
what are important considerations with history of dyspneic patients (10)
- acute vs chronic
- concurrent signs (cough)
- character: inspiratory/expiratory/mixed
- duration/frequency/timing
- relationship to activities (dust, exercise)
- vaccination/travel/worming
- respiratory noises; steror/stridor
- exercise tolerance/lethargy
- appetite
- response to prev treatment
what breeds of dogs are prone to tracheal collapse
toy breeds
what breeds of dogs are prone to lung fibrosis
terriers
what are cats prone to
asthma
what breeds of dogs are prone to laryngeal paralysis
large dogs
retrievers
what are older dogs prone to that can cause dyspnea
neoplasia
what are small breed dogs prone to
DMVD
what should be considered during clinical exam of dyspneic dogs (3)
- avoid excessive stress or struggling
- avoid dorsal recumbency for radiographs (esp if pleural disease suspected)
- give animal additional oxygen immediately
describe how you would clinically examinate a dyspneic dog (9)
- mucous membrane colour (pallour, cyanotic)
- respiratory rate
- resp pattern
- resp noises
- lymph nodes
- palpate cervical area
- pulse quality
- auscultation of heart and lungs and trachea
- percussion
what is dyspnea
sensation of difficult or laboured breathing
distress during severe resp disease (assume patient is experiencing discomfort)
what is tachypnea
increased resp rate (don’t confuse with panting)
what is orthopnea
inability to breath unless in an upright position
what is cyanosis
bluish to red-purple colour in the tissues due to increased amounts of deoyxgenated or reduced hemoglobin
arterial SaO2 (73-78%) on pulse oximetry before cyanosis is found with normal hematocrit
what is extrathoracic obstruction during inspiration (3)
- pharynx (stertor)
- laryngeal paralysis (stridor)
- tracheal collapse (honk)
what are intrathoracic obstructions during expiration (3)
- reactive airway disease –> asthma
- chronic bronchitis
- physical obstruction
how is thoracic percussion
percuss both sides of the chest
identify and asymmetry/areas of increased or decreased resonance
how does pleural effusion present with thoracic percussion
increased dullness ventrally
if dyspnea is caused by cardiac what will the heart rate and rhythm be
tachycardia +/- arrhythmia
what are the heart sounds if dyspnea is caused by cardiac reasons
usually murmurs +/- gallops
will there be inspiratory stridor if dyspnea is caused by cardiac reasons
not present
what will the response of cyanosis to O2 be if dyspnea is caused by cardiac reasons
none if R-L shunt
yes if severe pulmonary edema
if dsypnea is due to cardiac reasons then will the thorax be dull on percussion
yes if there is pleural effusion
if dyspnea is caused by respiratory reasons what will be the heart rate and rhythm
normal usually
sinus arrhythmia
will the heart sounds be normal if dyspnea is caused by respirtory
usually normal
will there be inspiratory stridor if there is resp causes of dyspnea
suggestive of URT obstruction
what will the repsonse of cyanosis to O2 if there resp causes
improves on O2
will the thorax be dull on percussion if dyspnea is caused by resp reasons
pleural effusion or mass
what are pleural space diseases that can cause dyspnea
- pleural effusion
- pneumothorax
what are the causes of pneumothorax (3)
- trauma
- spontaneous: secondary to bulla, necrosis, etc
- iatrogenic
what are the treatment of pneumothorax
- none/rest: minor trauma related tears often heal spontaneously in 2-3 days and need only monitoring
- thoracocentesis or thoracostomy tube
- surgery: if pneumothorax persists >72 hours; large lacerations and if cannot stabilize with a thoracostomy tube
what are mediastinal diseases that can cause dyspnea (5)
- masses: neoplasia/lymphadenomegaly/granulomas/brachial cysts
- megaesophagus
- pneumomediastinum
- mediastinitis
- mediastinal hemorrhage
what are the most common mediastinal neoplasia masses
- lymphoma
- thymoma
what are the differential diagnosis causes of neoplastic mediastinal masses (3)
- ectopic thyroid carcinoma
- chemodectoma
- neuroendocrine
how are mediastinal masses diagnosed
fine needle aspiration
flow cytometry may be helpful in distinguishing
what are the types of thymomas
- invasive
- non-invasive
what are the paraneoplastic effects of thymomas
hypercalcemia
what are other physical effects of mediastinal masses (6)
- venous obstruction: cranial vena cava can cause edema
- dysphagia: aspiration pnemonia
- horner’s sydrome: isruption of a nerve pathway from the brain to the face and eye on one side of the body
- hypertrophic osteopathy
- myasthenia gravis (thymoma)
- other paraneoplastic effect
how do mediastinal masses cause dyspnea (4)
- pleural effusion
- airway compression
- space occupying
- laryngeal paralysis
what is hypertrophic osteopathy
unusual paraneoplastic syndrome: pallisades of sub-periosteal new bone on distal limbs (metapodial bones) usually secondary to a thoracic mass
causes limb thickening & lameness
what are miscellaneous pulmonary diseases causing dyspnea (8)
- neoplasia (primary or secondary)
- idiopathic pulmonary fibrosis
- paraquat poisoning
- pneumonia
- parasitic
- hemorrhage
- edema
- pulmonary thromboembolism
what breed is idiopathic pulmonary fibrosis seen in
west highland white terriers
“westies disease”
what is the cause of idiopathic pulmonary fibrosis
unknown
may be non specific interstitial pneumonitis
what is the onset of idiopathic pulmonary fibrosis
gradual
progressive deterioration
what can idiopathic pulmonary fibrosis be secondary to
other resp conditions
what are the signs of idiopathic pulmonary fibrosis (6)
- dyspnea
- tachypnea
- exercise intolerance
- cough (esp if also have CAD)
5. marked crackles on auscultation - very loud
- otherwise normal
how is idiopathic pulmonary fibrosis diagnosed (3)
clinical presentation
imaging
bronchoscopy
how is idiopathic pulmonary fibrosis treated (4)
- anti-inflammatory: glucocorticosteroids (oral or inhaled), mycophenolate
- bronchodilators (oral or inhaled)
- antibacterial therapy if secondary infection
4. sildenafil (or pimobendan) if pulmonary hypertension: most helpful
how do cats present with idiopathic pulmonary fibrosis
cough and dyspnea
how are cats with idiopathic pulmonary fibrosis treated (3)
corticosteroids
sildenafil
bronchodilators
what is the prognosis of idiopathic pulmonary fibrosis in cats
guarded
more rapidly progressive
what is paraquat poisoning
herbicide
pneumotoxin
what does paraquat poisoning result in (3)
- severe dyspnea initially with minimal radiographic findings
- initial alveolitis
- hemorrhagic progresses to severe pulmonary fibrosis
what is the prognosis of paraquat poisoning
poor
what can make paraquat poisoning worse
oxygen supplementation
formation of supraoxides in the lungs
what are the causes of bacterial pneumonia (2)
- Bordatella spp
- Pasteurella spp
when can bacterial pneumonia be caught
environmental (spontaneous) or hospital
what is the signalment of bacterial pneumonia
dogs > cats
younger dogs
what does bacterial pneumonia cause
venetral lobar alveolar pattern (early and recovery interstitial)
what are the predispositions of bacterial pneumonia (4)
- prolonged recumbency (GA)
- foreign body
- dysphagia (megaesophagus, orally dosed for medication, feeding)
- damage to respiratory defences (CAD)
what are the viral causes of pneumonia in cats and dogs
- canine distemper
- canine influenza
- feline calcicivirus
what are the causes of pneumonia
- bacterial
- viral
- parasitic
- mycotic
how does bacterial pneumonia present on radiograph (4)
- interstitial pattern early in disease
- alveolar pattern: air bronchograms are classical
- middle right lung lobe pathology or cranioventral distribution
4. look for foreign bodies, megaesophagus and other thoracic diseases
describe the radiographic changes and ddx
consolidation of right middle lung lobe
bacterial pneumonia
what are the radiographic changes and ddx
megaesophagus, depression of trachea
air filled bronchus surrounded by pneumonia lung
bacterial pneumonia
how is bacterial pneumonia diagnosed (4)
- hematology
- transtracheal/endotracheal wash and cytology and culture
- bronchoscopy with bronchoalveolar lavage and culture and cytology
- cytology
what are the hematologic signs of bacterial pneumonia (2)
- left shift neutrophilic leukocytosis
- monocytosis if more chronic
what is seen on cytology in bacterial pneumonia
degenerative neutrophils/monocytes
intracellular bacteria
what can bacterial pneumonia result in
sepsis which can lead to additional acute lung injury and ARDS (death)
how is mild, stable bacterial pneumonia treated
amoxycillin-clavunate, trimethoprim-sulfonamide
how is moderate and severe bacterial pneumonia treated
beta-lactam and fluroquinolone/aminoglycosides
broad coverage: four quadrants gram +, gram -, anaerobes, mycoplasma spp
IV injectable therapy then change to oral once its under control
long term is usually required 4-8 weeks
how is bacterial pneumonia managed (3)
- supplementary O2
- nebulization: mobilizes airway secretions (sterile saline + gentamicin) + may need bronchodilator
- supportive care: IV, coupage, bronchodilators
what are the symptoms of mycotic pneumonia (5)
similar for all pneumonias
- abnormal resp pattern
- tachypnea
- cough (pulmonary granulomas)
- exercise intolerance
- systemic signs: inappetance, weight loss, fever, lameness, lymphadenopathy, chorio-retinitis or anterior uveitis, draining fistula tracts
what is the etiology of mycotic pneumonia
- Blastomycosis
- Histoplasmosis
- Coccidiomycosis
- Aspergillosis
what can cause pulmonary edema (7)
- cardiogenic causes (heart failure)
- toxins (bacterial, smoke, paraquat, endogenous)
- anaphylaxis/shock
- near drowning
- neurogenic: seizures, electric shock
- over-perfusion(too much IV fluids): hypoalbuminemia
- negative pleural pressure in upper airway obstruction
how is pulmonary edema treated (3)
- diuretics
- oxygen
- specific treatment for underlying cause
what are the causes of pulmonary hemorrhage (4)
- trauma (RTA)
- coagulopathies (coumarin rodenticides)
- pulmonary thromboembolism
- Angiostrongylus vasorum
what are the causes of pulmonary thromboembolism (7)
- heartworm
- nephrotic syndrome (loss of antithrombin III)
- hyperadrenocorticism
- bacterial endocarditis
- immune mediated hemolytic anemia
- corticosteroid therapy
- iatrogenic
what are the signs of pulmonary thromboembolisms
- profound dyspnea/distress
- hypoxemia
- sudden death
how are pulmonary thromboembolisms diagnosed (4)
- minimal radiographic changes but may have right sided cardiomegaly +/- vascular attenuation or tortuosity
- contrast angiography; CT
- hematology/coagulation profile
- pulmonary hypertension on echo
what are the radiographic changes seen
inverted D shape: right sided enlargement (RV)
hypovascular lung field
attenuation of caudal lobe pulmonary arteries
how is pulmonary thromboembolism treated
- heparin
- aspirin or cloidogrel
- sildenafil where PH present
- thrombolysis?
treat underlying cause
what are airway diseases that cause dyspnea (4)
- laryngeal paralysis
- tracheal collapse
- foreign bodies
- feline asthma
what are the clinical features of feline asthma
- any age commonly in young to middle aged cats (1-3 yo)
- siamese appear predisposed
what are the clinical signs of feline asthma (3)
- variable
- chronic or intermittent cough
- acute respiratory distress: open mouth breathing, audbile wheezing
what are the main differentials for acute dyspnea in cats (7)
- feline bronchial asthma
- congestive heart failure (pleural effusion, pulmonary edema)
- lung contusion
- pneumonia
- hydrothorax or pneumothorax
- diaphragmatic and pericardioperitoneal diaphragmatic hernia
- upper airway obstruction
what are the radiographic changes seen in feline asthma (5)
- hyperlucency and hyperinflation
- flattened diagphragm indicating air-trapping
- broncho-interstitial to bronchial patterns
- abnormal soft tissue opacities: granulomas, mucoid plugs
- erophagia (swallow air)
what radiographic changes are seen here
patchy infiltrates
feline asthma
what radiographic change is seen here
gas in stomach due to feline asthma
what change is seen here
flattened diaphragm
feline asthma
what is the changes seen here
bronchial pattern
middle lung lobe collapse
air trapping
how is feline asthma diagnosed (4)
dyspnea
cough
BALF cytology - eosinophilia
radiograph: bronchial pattern, middle lung lobe collapse, air trapping
what is the acute treatment of feline asthma
- oxygen
- cage rest
- bronchodilator
- corticosteroids
what bronchodilators used in feline asthma (5)
- terbutaline
- aminophylline
3. salbutamol - inhaled
- adrenaline
- atropine
what corticosteroids are used to treat feline asthma (3)
- methylprednisolone
- dexamethaonse
3. inhaled futicasone
what is the long term treatment of feline asthma (5)
- control environment
- control endoparasites (fenbendazole)
- bronchodilators (acute or high grade)
- antibiotics - doxycycline
- corticosteroids (chronic)
what long term bronchodilators are used to treat feline asthma
- salbutamol (albuterol) inhaled
- salmeterol (serevent) inhaled
- terbutaline: 0.625 mg-1.25 mg per os 12 h
- theophylline 20mg/kg per os 24h
what long term corticosteroids are used to treat feline asthma
- prednisolone 0.5mg/kg po q 24 hours for 7-14 days and then taper
- futicasone, budesonide, beclomethasone inhaled
