Loss of athletic performance is a common early sign of underlying injury or disease in a horse.
The changes are often subtle and require a detailed veterinary examination to help localise the problem to a specific area or body system and determine the need for further diagnostic tests. The diagnostic process may involve investigation of the respiratory system via endoscopy, transtracheal or bronchoalveolar lavage; lameness work-up including nerve and joint blocks, radiology and musculoskeletal ultrasonography or internal organ system assessment, involving blood sample analysis and abdominal and thoracic ultrasonography.