Equine asthma overview Flashcards
(20 cards)
Classification - severe vs mild-moderate
Severe equine asthma
= sEA
= RAO (recurrent airway obstruction)
= SPAOPD (summer pasture associated obstructive pulmonary dz)
Mild-to-moderate asthma
= mEA
= IAD (inflammatory airway dz)
mEA vs sEA: Clinical presentation - age
mEA
- young (any age possible)
sEA
- >7y/o
mEA vs sEA: Clinical presentation - CS
mEA
- decreased performance
- no resting dyspnoea
- occasional cough
- >3w
sEA
- decreased performance
- with resting dyspnoea
- frequent cough
- variable
mEA vs sEA: Clinical presentation - progression
mEA
- spontaneous improvement, response to tx
- no recurrence
sEA
- long term tx/management
- recurrence
mEA vs sEA: Clinical presentation - hx
mEA
- stabled
sEA
- stabled or on pasture
- familial hx
- seasonality
mEA vs sEA: diagnostic confirmation - endoscopy
mEA
- tracheal mucus +++
sEA
- tracheal mucus +++++
mEA vs sEA: diagnostic confirmation - BAL cytology
mEA
- increased neutrophils + eosinophils + macrophages
sEA
- increased neutrophils +++
mEA vs sEA: diagnostic confirmation - pulmonary function
mEA
- 0/+
sEA
- ++/+++
Aetiology
- strong association with environment and feeding
- inflammation is key to the syndrome
- mechanisms poorly understood
What neutrophil percentage of the total nucleated cells is indicative of severe asthma?
- 25%
How small do particles need to be to trigger disease or embed/reach deep into the lung?
- less than 5um
Breathing zone of a horse
- 30cm around the muzzle and nostrils
Do hay nets have a high concentration of airborne respirable dust?
- yes, 4x higher
Causes of asthma
Non-allergic inflammatory response
- endotoxin
- moulds
- noxious gases e.g. ammonia
Genetic
- familial risk for moderate/severe CS
- RAO: criterion of heritability soundness in breeding stallions?
HS
- exacerbation with hay dust
- allergic reaction? HS type I & III
- possible role of fungal spores
Pathophysiology
Airway hyper-responsiveness
- overreaction of smooth muscle constriction
- overtime the muscles will hypertrophy causing hyper responsiveness
Bronchospasm
- bronchodilators are effective
- secondary to inflammation
Inflammation
- airway neutrophilia is characteristic
- activation of macrophages occur
Mucus accumulation
- consistent finding in equine asthma
- associated to neutrophilia?
- long persistence (during remission)
- exacerbations increase viscoelasticity
Tissues remodelling
- due to inflammation for prolonged periods
- increased smooth muscle mass
- increased contraction force
- peri bronchial fibrosis
- epithelial hyperplasia
- bronchiectasis
T/F: the more mucus, the more severe the condition is
- true
T/F: the more mucus, the more coughing
- true
Diagnostic options
- hx
- PE
- auscultation
- endoscopy
- cytology (BAL & TTW)
- pulmonary function testing
Auscultation
- rebreathing bag (look for tolerance, cough, recovery)
- specially important for mEA
- wheezes, crackles, tracheal rattles
Endoscopy
- rule out upper airway diseases
- tracheal mucus
- 1h post-exercise
- carina
