INFLAMMATORY AIRWAY DISEASES Flashcards
important inflammatory airway diseases of the horse
▪ Exercise-Induced Pulmonary Hemorrhage
▪ Mild-Moderate Equine Asthma
▪ Severe Equine Asthma
EXERCISE-INDUCED PULMONARY HEMORRHAGE
- Signalment
- any horse that works at a high rate of speed for any length of time
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Signalment
▪ Any age
▪ Any breed
> Thoroughbreds
> Standardbreds
> Quarter horses
▪ Any sex
▪ Genetic component?
EIPH
▪ Pathogenesis
▪ During strenuous exercise, shear forces across the lung > Mean pulmonary artery pressure > > 90mm Hg
> Increased capillary pressure
> Pulmonary capillary failure
> Extravasation of blood
▪ Arteriovenous remodelling > more likely to bleed again, ie. predisposition after first time
> Loss of compliance
> Increased capillary pressure
> Pulmonary capillary failure
> Extravasation of blood
EIPH
▪ Prevalence
▪ Clinical signs
▪ Diagnosis
Prevalence
▪ Epistaxis= 0.15-0.84% (very rare)
▪ Airway hemorrhage= 45-90%
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Clinical signs
▪ Epistaxis
▪ Abnormal lung sounds
▪ Decreased/poor performance
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Diagnosis
▪ Epistaxis post strenuous exercise
▪ Endoscopy
▪ Bronchoalveolar lavage (within 2 weeks)
EIPH
▪ Treatment, prophylaxis
▪ No treatment currently available
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Prophylaxis
▪ Furosemide, 4 hours prior to exercise (modulates blood pressure)
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investigated but no effect
▪ Anti-inflammatories
▪ Bronchodilators
▪ Phosphodiesterase inhibitors
▪ Procoagulants
▪ Nasal dilator strips
EIPH
▪ Prognosis
Guarded for strenuous exercise
▪ Horses with epistaxis more likely to have epistaxis again
▪ Horses with grades 3-4 hemorrhage
> More likely to have poor performance and shorter career
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▪ May develop pulmonary fibrosis
▪ Risk of fatal hemorrhage very low
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- but in terms of survival, there are no problems
MILD-MODERATE EQUINE ASTHMA
▪ Definition
▪ Dysregulation of inflammatory cell
homeostasis in the airway lumen leading to
variable clinical signs
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▪ Previously > Inflammatory airway disease
MILD-MODERATE EQUINE ASTHMA signlament
▪ Young- middle age
▪ Any breed
▪ Any sex
MILD-MODERATE EQUINE ASTHMA
▪ Risk factors, pathophysiology
▪ Stable housing
▪ Poor ventilation
▪ Presence of airway irritants
▪ Respiratory infection
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Pathophysiology
▪ Multifactorial
▪ Increased airway mucus
▪ Airway hyperresponsiveness
▪ Increased % of one or more cell types
MILD-MODERATE EQUINE ASTHMA
▪ Clinical signs
▪ Decreased performance
▪ Delayed recovery after exercise
▪ Exercise intolerance
▪ Chronic, intermittent cough
▪ Serous-mucoid nasal discharge
MILD-MODERATE EQUINE ASTHMA
diagnosis
▪ Endoscopy
▪ Bronchoalveolar lavage
▪ Rule-out other etiologies
mild-moderate equine asthma grading scale correlates with what?
- number of neutrophils we see on BAL
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Tracheal mucous score
▪ Positively correlated with neutrophil %
▪ Negatively correlated with eosinophil %
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Bronchoalveolar lavage
▪ >10% neutrophils
▪ or
▪ > 2-5% mast cells
▪ or
▪ >1-2% eosinophils
MILD-MODERATE EQUINE ASTHMA
▪ Phenotypes
▪ Neutrophilic
▪ Eosinophilic
▪ Metachromatic/mastocytic
Neutrophilic mild-moderate equine asthma
- who gets it?
- associated with?
▪ Most common in horses > 7 years old
▪ Associated with:
▪ Chronic coughing
▪ Increased tracheal mucus
▪ Cold, dry environments
Eosinophilic milkd-moderate equine asthma
- who gets it?
- associated with?
▪ Most common in horses < 5 years of age
▪ Associated with:
▪ Respirable dust exposure
▪ Not correlated to parasitism
▪ Airway hyperresponsiveness
Metachromatic/mastocytic mild-moderate equine asthma
- association, characteristics?
▪ Airway hyperresponsiveness
▪ Poor performance
▪ Most difficult to manage > no good drug that is a mast cell stabilizer
MILD-MODERATE EQUINE ASTHMA
▪ Treatment principles
- systemic treatment options
Treatment principles
▪ Decrease pulmonary inflammation
▪ Decrease airway hyperresponsiveness
▪ Decrease airway mucous production
▪ Environmental management
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Systemic treatment options
▪ Corticosteroids
> Dexamethasone
> Prednisolone
▪ Bronchodilators
> Clenbuterol
> Aminophylline
SEVERE EQUINE ASTHMA
▪ Definition
Chronic, progressive, severe pulmonary
inflammation
▪ Excessive mucus production
▪ Airway neutrophilia
▪ Bronchial hyperreactivity
▪ Bronchospasm
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- a horse with mild-moderate will not necessarily ever have a severe case! and horses can have a severe case without having prior cases.
SEVERE EQUINE ASTHMA
▪ Signalment, clinical signs
Signalment
▪ Usually middle-aged or older
▪ Any breed
▪ Any sex
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Clinical signs
▪ Chronic cough
▪ Serous- mucoid nasal discharge
▪ Increased respiratory effort at rest
▪ Severe exercise intolerance
▪ Episodic respiratory distress
▪ Weight loss
SEVERE EQUINE ASTHMA
▪ Two subtypes
Barn-associated
▪ Temperate-cool climates
▪ Clinical late fall-winter
▪ Housed primarily in stall/barn
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Summer pasture-associated
▪ Hot, humid climates
▪ Clinical spring-late fall
▪ Housed at pasture
SEVERE EQUINE ASTHMA
▪ Diagnosis
▪ History
▪ Physical examination
> Increased respiratory effort at rest
-> Abdominal lift
-> Nostril flaring
-> “heave line”
-> Audible wheezing
▪ Auscultation
> High and low-pitched expiratory wheezes
▪ Response to inhaled or systemic bronchodilator
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Endoscopy
▪ Scant - mild tracheal mucous
▪ Collapsing bronchi > shouldnt be responding to this mechanical stimulus in healthy animal
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Bronchoalveolar lavage (this is the best!)
▪ >20% neutrophils
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▪ Thoracic ultrasonography?
▪ Thoracic radiographs
▪ Pulmonary function testing
> Bronchoprovocation
▪ Biopsy
> Endoscopic
> Thorascopic
horse with severe equine asthma may also have what other disease? why?
MAY ALSO HAVE PNEUMONIA
▪ Impaired pulmonary defences
▪ Impaired airway clearance
SEVERE EQUINE ASTHMA
▪ Principles of treatment
▪ Reverse bronchoconstriction
▪ Decrease airway inflammation
▪ Treat concurrent pneumonia
▪ Modify the environment
▪ Treat early and aggressively
severe equine asthma - chronic and progressive cases can have what issues?
▪ Cachexia
▪ Bullae
▪ Pneumothorax
▪ Pneumonia/pleuropneumonia
▪ Pulmonary edema
▪ Cor pulmonale
▪ Heart failure
SEVERE EQUINE ASTHMA
- treatment options
▪ Inhaled bronchodilators
> Lev-albuterol
▪ Systemic bronchodilators (better as they can more easily affect the deepest airways)
> Clenbuterol
> N-butylscopalamine
> Atropine
▪ Intranasal oxygen
▪ Systemic corticosteroids
> Dexamethasone
> Prednisolone
▪ Inhaled corticosteroids
SEVERE EQUINE ASTHMA
▪ Environmental management for Barn-associated
▪ Wet hay prior to feeding
▪ Feed on the ground
▪ Feed all-pelleted diet
▪ Remove round bales
▪ Use low-dust/ no bedding
▪ Improve ventilation in barn
▪ Remove any hay stored in loft
▪ Increase turnout time
▪ Remove horse from barn when cleaning
SEVERE EQUINE ASTHMA
▪ Environmental management for Pasture-associated
▪ Decrease time on pasture
▪ Mow pastures frequently
▪ Turn out in dry lot
▪ Well-ventilated stall > Fans in stall
▪ Wet hay or feed all-pelleted diet
▪ Use low dust bedding
▪ House away from fields during harvest
