SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
50% of Thoroughbred and Standardbred racehorses. The duration of the problem
has been variously described as ranging from 4 to 12 weeks.
The importance of IAD as a cause of poor performance is undefined. No studies
have induced lower airway inflammation in young performance horses that has led to
a demonstrable change in any parameter of performance. However, much
speculation has been offered as to the likely effect of this syndrome on racehorses in
which peak lung function is required to produce maximal performance, and small
decrements in this performance may have a major impact on economic outcomes.
Horses with IAD do not exhibit respiratory stress, nor do they have consistent
alterations in lung function that can be measured with current techniques. In
addition, horses with evidence of lower airway inflammation may not have a history
of exercise intolerance or poor performance, particularly if they are not involved in
athletic undertakings. However, in a number of studies, horses presented with poor
performance commonly had endoscopic or cytological evidence of lower airway
inflammation. Care must be taken when considering this potential link between poor
performance and airway inflammation as association does not equate to causation,
and there are potentially many other causes of poor performance or exercise
intolerance in any individual animal.
Diagnosis
Many diagnostic techniques have been used to detect IAD. A careful physical
examination is essential. This, plus the results of endoscopy and tracheal aspirates
or BAL generally form the basis for the condition’s diagnosis and subsequent
therapeutic and/or management recommendations. The use of endoscopy is a
standard diagnostic procedure in horses with poor performance and suspected IAD.
Endoscopy allows not only direct visualization of the upper and lower airways for the
presence of inflammatory exudates or blood, but also allows guided collection of
samples from the lower trachea and large bronchi. These samples may be used for
cytological and bacteriological investigations.
When pulmonary irritation occurs, mucus production increases with resultant
accumulation of mucus within the airways. Therefore excess mucus in the trachea
and mainstem bronchi has been used as evidence for the presence of airway
inflammation. Excess mucus is a common endoscopic finding in racehorses.
Although collection of tracheal aspirates or BAL is now considered a routine
procedure in many practices, there remain are a number of controversial issues
associated with their interpretation. Most notably these include the differing
definitions of normal and abnormal cytological findings among investigators, the
significance of increased numbers of inflammatory cells and mucus, particularly in
performance horses, and the relevance of