12 – Respiratory 4 Flashcards
What might the pathogenesis of bacterial pneumonia be?
- Secondary to viral respiratory infection
o Stress/immunosuppression
o Transport (shipping fever)
o May be preceded by upper respiratory symptoms - Aspiration pneumonia
o Esophageal obstruction (choke)
o Dysphagia
Transport (history)
- Shipping fever
- ‘common’ in horses and cattle
o Head held high for a long period of time=less movement with the mucociliary escalator
What are the clinical findings of bacterial pneumonia ?
- Fever
- Coughing
- Nasal discharge (bilateral)
- Tachypnea
- Increased respiratory effort
- Abnormal lung auscultation
How do you diagnosis bacterial pneumonia?
- History and clinical signs
- CBC
- (trans) tracheal wash
o Cytology
o Bacterial C&S (large animal) - BAL (small animal, cattle)
- Diagnostic imaging
o Lung radiographs
o Ultrasound
Mild to moderate equine asthma (was inflammatory airway disease)
- Mild: poor performance without cough
- Moderate: cough symptoms
Severe equine asthma (was recurrent airway obstruction)
- Variant equine pasture asthma
- Lay term: heaves
- NOT called COPD
What is the pathogenesis of equine asthma?
- Non-septic lower airway inflammation
- MULTIFACTORIAL
o Airway hyperresponsiveness of airborne antigens
o Different phenotypes
o Genetic predispositions
o Airway microbiota - Excessive mucus secretion + bronchoconstriction
- Chronic=airway remodelling
Individual predisposition: equine asthma
- “allergic phenotype”
- Heritability in certain breeds
- Insect bite hypersensitivity
Environment: equine asthma
- Pasture: pollen
- Areana/stall: dust, gases
- Hay/straw: molds/fungi, endotoxin
o Just a loss round bale=not good - Poor ventilation
Mild to moderate equine asthma
- Usually younger (but any age)
- Poor performance:
- Chronic cough (>3 weeks), occasional/intermittent
- NO increased respiratory effort at rest
- Prognosis: good
- Mild increase in neutrophils
- Risk of reoccurrence=low
Severe equine asthma: “heaves”
- Horses usually holder than 7 years
- Frequent coughing
- Exercise intolerance
- INCREASED respiratory effort at rest: “heaves line”
- Life-long management (cannot be cured)
- Moderate to severe increase in neutorphils
Severe asthma: long term
- Hypoxic vasoconstriction
- Arterial remodeling and thickening
- Pulmonary hypertension
o Cor pulmonale
Wheezes vs. crackles
- Wheezes=asthma=narrowing of airway
- Crackles=infection
What are your main differential diagnoses for asthma?
- Bacterial pneumonia: CBC and tracheal wash
- Exercise induced pulmonary hemorrhage: endoscopy and BAL
- Viral respiratory disease (EIV, EHV-1,4): PCR of nasopharyngeal swab
- do a BAL OR give it a bronchodilator and see if it responds (“busocpan test”)
What are some less common differential diagnoses for asthma?
- Lungworm: Dictyocaulus arnfieldi
o History: exposed to donkeys - Equine multinodular pulmonary fibrosis
- Mitral regurgitation/left-sided heart failure
- Thoracic mass compressing trachea
Management of asthma
- Antigen avoidance
o Do not store hay above horses
o Remove horses from barn when sweeping
o Water-down dusty arenas
o Low-dust feed and bedding - *tailor the plan to individual situation increases owner compliance
Exercise induced pulmonary hemorrhage (‘bleeders’)
- Race horses
- Performance at max capacity
- Hemorrhage within airways (pulmonary vessels)
- Diagnosis: endoscopy +/- BAL
What is the pathogenesis of exercise induced pulmonary hemorrhage?
- Increased capillary pressure
- Caudo-dorsal lung most affected
- Micro to macroscopic hemorrhage
Exercise induced pulmonary hemorrhage: signalment
- Horse undergoing strenuous exercise
- Poor performance: many differentials
- Epistaxis following exercise (DDx: ethmoidal hematoma, guttural pouch mycosis)
Exercise induced pulmonary hemorrhage: diagnosis
- Upper airway endoscopy
o Scoring of tracheal blood
o Immediately following exercise - Lung radiographs
o Increased interstitial opacity in dorsal caudal lung - BAL
o RBC
o **hemosiderophages - **timing of diagnostic is important
Is exercise induced pulmonary hemorrhage and inflammatory airway disease related?
- NO evidence
o Correlation does NOT always mean causation - Both contribute to poor performance
- Can be concurrent
