RAO stands for
Recurrent Airway Obstruction
RAO used to be called COPD, or
Chronic Obstructive Pulmonary Disease
Organic dusts
When susceptible horses are put into problematic environments, this happens
massive influx of neutrophils invade the airway lumen
This happens in ____ (time)
6-8 hours
What causes bronchospasm?
Inflammatory mediators (IL, cytokines, leukotrienes) acting on cholinergic nerves
What happens to mucus?
Increase production and viscosity
= mucus accumulation
What happens to the airway?
airway wall thickening: edema (acute) and remodeling (chronic)
More prevalent in which hemisphere?
Northern
Is there a genetic component?
Yes
Clinical signs (acute):
Advanced stages of heaves
Struggle to breathe is so intense that horse is unable to eat and loses weight
Heave lines on abdomen
Horses with heaves tend to be
older
RAO is similar to
Summer-Pasture Associated Obstructive Pulmonary Disease
3 principles of management and prevention
Drugs: NSAIDS:
What do they do?
contraindicated.
decrease production of PGE2 (prostaglandin that inhibits inflammation and prevents bronchospasm)
Drugs: Corticosteroids:
What do they do?
prevent pro-inflammatory process
prevent down-regulation of beta-2-adrenoceptors
increase appetite
Drugs: Dexamethasone
How long until improvement?
gradually reduce dose to minimum
Improvement in 3-7 days
Drugs: Beclomethasone and Fluticasone:
Administration?
must be given by Aeromask
severity of obstruction prevents the deposition of inhaled steroids in the lungs
Drugs: Bronchodilators
What do they do? What don’t they do?
Improve mucus clearance
do NOT treat inflammation
Drugs: Bronchodilators
Names
Clenbuterol (Ventipulmin)
Albuterol
Pirbuterol
Salmenterol
Drugs: Bronchodilators
Side effects
Sweating
Trembling
Tachycardia (raised HR)
Agitation
Duration of clenbuterol and salmeterol effects
6-8 hours
duration of albuterol and pirbuterol
1-2 hours