Reaccurant airway obstruction Flashcards
What is RAO?
The most common cause of coughin in the UK, with a prevalence of 14% (Reid et al, 2007). It is an inflammatory allergic response which affects the bronchi and bronchioles.
What are other names for RAO?
Broken winds & Heaves
What are the clinical signs of RAO?
- Heaving (abdonimal muscles helping in exhaling)
- Nasal discharge
- Coughing
- Wheezing
- Onset of dispair
- Exercise intolerant (inc. increased HR & resp. rate).
Horse is generally unfit in appearance.
What are the 3 primary contributors to RAO?
Aspergillus fumigatis
Thermactinomyces vulgaris
Faeria rectvirgula
(Bacterial + mold spores, dust particles, pollons)
Who generally sufferes from RAO?
Mature (where 12% have some degree of allergern induces airway inflam. (Kahn 2010)).
Mostly in horses > 6 years (Robinson, 2001).
How is RAO contracted?
Inhalation of dust particles or bacterial or mold spores.
How is RAO treated?
Use of bronchodilators and anti-inflam. drugs to help ease horse breathing.
Cant be cured therefore also have the problem, have to try ways to reduce problem such as soaking hay to ensure dust particles are stuck and ensure good environmental management.
How is RAO diagnosed?
History of the horse- how the horse is housed? What environment they are usually in? What feed it gets? Does it usually struggle with exercise?
Clinical signs, including visible.
Endoscopy- will usually see streams of mucous and damage to tissues due to extreme coughing.
What happens to the epithelial layers in the lungs due to RAO?
Become more sensitive as the cell function is compromised and changed OR structure of the organ is changed, this can lead to a delayed hypersensitivity reaction and an over reaction of the natural defence mechanisms.
What happens when excess inflam. results?
Increased mucous production, and become mroe sensitive to cough refelx = more mucous lining resp. tract leading to decreased diameter of the tract and greater resistance therefore bronchioles can be blocked due to excess mucous leading to reduces gas exchange = hypoxic.
Bronchoconstriction can also occur and greater coughing actions to particles that wouldnt normally cause a problem there more susceptible to secondary bacterial infections.
What is Summer Pasture Associated RAO?
It is similar to RAO, in that it is an allergic reponse causing inflammation in the lungs, but it is associated with horses at pasture and has a seasonal occurance.
It is harder to diagnose because is it dependant of what allergen it is caused by.
To treat this, generally you have to more the horse away from the cause not the other way around (as you hant generally more pollen away from horse etc)
If medication was use to help treat (but not cure) RAO, what would be used and why?
Corticosteroids as there would dampen the Immune system ad reduce hypersensitivity.
Bronchodilators to increase diameter and allow greater air flow and also anti-inflam. to reduce the resistance in the lungs.
