There are many causes for poor performance, the most common being related to the respiratory or cardiac system. A complete evaluation of the horse for poor performance will involve discussion of the history, cardiac and respiratory evaluation and diagnostics that would be appropriate to determine the cause.

This may involve:

• Cardiac ultrasound and ECG

• Exercising ECG

• Endoscopy of the upper airway

• Bronchoalveolar lavage (BAL) of the lower airway

• Other appropriate diagnostics based on the exam and/or the diagnostic findings