SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
present in the airways as opposed to the amount of mucus collected with tracheal
aspirate or BAL, and will allow determination of relative increases in the numbers
and type of inflammatory cells. The amount of mucus in washes increases when
pulmonary irritation occurs, such as in cases of IAD. However, the amount of mucus
that constitutes an abnormality is controversial. This is particularly the case in horses
where there are increased amounts of mucus, but no or only mild increases in the
number of neutrophils, or else many activated macrophages. Furthermore, these
findings may be present in horses not exhibiting overt signs of respiratory disease. It
is currently not known at which point mucus accumulation and/or airway
inflammation become clinically significant, especially for different levels of
performance. Furthermore, the persistence of these changes has also not been
determined.
IAD differs from chronic obstructive pulmonary disease/recurrent airway obstruction
(COPD/RAO) in terms of cytology. IAD results in BAL cytology changes (mild
neutrophilia, lymphocytosis, monocytosis) that are reported to be distinguishable
from those seen with RAO (marked neutrophilia, lymphopenia, alveolar
monocytopenia). While neutrophilic IAD is the most commonly encountered form of
the condition, eosinophilic, mastocytic or mixed sub-types can also occur, with the
designation being based on the predominant inflammatory cell.
Management and Treatment
Successful treatment of inflammatory airway disease (IAD) requires environmental
management to minimize exposure to irritants, and combination drug therapy to
reduce pulmonary inflammation and prevent bronchoconstriction (if it is thought to be
a factor). Aerosolized drug therapy of corticosteroids and/or bronchodilators is an
efficient means of treatment for most horses with IAD, and is to be preferred over the
systemic use of similar drugs.
Aerosol therapy is becoming more and more widely practiced and is very appropriate
for medical treatment of both RAO and IAD. Inhalation therapy improves drug safety
and efficacy by reducing the total therapeutic dose, minimizing drug exposure to
other body systems, and allowing direct delivery of the drug to the lower respiratory
tract. However, the drugs are usually more expensive than the equivalent
systemically administered agents. In most instances, the response to aerosolized
drug administration is more rapid than systemic drug administration.
Several devices have been designed for convenient administration of aerosolized
drugs formulated in a metered-dose inhaler (MDI) canister. The advantages of an
MDI system include rapid administration, consistent dose delivery, minimal risk of
pulmonary contamination with environmental microorganisms, ease of
cleaning/maintaining equipment, wide availability, and no requirement for electricity.
The Equine AeroMask TM (Canadian Monaghan, Ontario, Canada) is the most
versatile of the delivery systems because it can be used for administration of
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