Equine asthma overview Flashcards

(20 cards)

1
Q

Classification - severe vs mild-moderate

A

Severe equine asthma
= sEA
= RAO (recurrent airway obstruction)
= SPAOPD (summer pasture associated obstructive pulmonary dz)

Mild-to-moderate asthma
= mEA
= IAD (inflammatory airway dz)

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2
Q

mEA vs sEA: Clinical presentation - age

A

mEA
- young (any age possible)

sEA
- >7y/o

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3
Q

mEA vs sEA: Clinical presentation - CS

A

mEA
- decreased performance
- no resting dyspnoea
- occasional cough
- >3w

sEA
- decreased performance
- with resting dyspnoea
- frequent cough
- variable

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4
Q

mEA vs sEA: Clinical presentation - progression

A

mEA
- spontaneous improvement, response to tx
- no recurrence

sEA
- long term tx/management
- recurrence

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5
Q

mEA vs sEA: Clinical presentation - hx

A

mEA
- stabled

sEA
- stabled or on pasture
- familial hx
- seasonality

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6
Q

mEA vs sEA: diagnostic confirmation - endoscopy

A

mEA
- tracheal mucus +++

sEA
- tracheal mucus +++++

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7
Q

mEA vs sEA: diagnostic confirmation - BAL cytology

A

mEA
- increased neutrophils + eosinophils + macrophages

sEA
- increased neutrophils +++

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8
Q

mEA vs sEA: diagnostic confirmation - pulmonary function

A

mEA
- 0/+

sEA
- ++/+++

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9
Q

Aetiology

A
  • strong association with environment and feeding
  • inflammation is key to the syndrome
  • mechanisms poorly understood
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10
Q

What neutrophil percentage of the total nucleated cells is indicative of severe asthma?

A
  • 25%
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11
Q

How small do particles need to be to trigger disease or embed/reach deep into the lung?

A
  • less than 5um
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12
Q

Breathing zone of a horse

A
  • 30cm around the muzzle and nostrils
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13
Q

Do hay nets have a high concentration of airborne respirable dust?

A
  • yes, 4x higher
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14
Q

Causes of asthma

A

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

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15
Q

Pathophysiology

A

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

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16
Q

T/F: the more mucus, the more severe the condition is

17
Q

T/F: the more mucus, the more coughing

18
Q

Diagnostic options

A
  • hx
  • PE
  • auscultation
  • endoscopy
  • cytology (BAL & TTW)
  • pulmonary function testing
19
Q

Auscultation

A
  • rebreathing bag (look for tolerance, cough, recovery)
  • specially important for mEA
  • wheezes, crackles, tracheal rattles
20
Q

Endoscopy

A
  • rule out upper airway diseases
  • tracheal mucus
  • 1h post-exercise
  • carina