Exercise-induced pulmonary hemorrhage (EIPH), or lung bleeding, and inflammatory airway disease (IAD) are by far the most common respiratory problems. A diagnosis of EIPH is often made shortly after strenuous exercise by visualizing blood in the trachea using an endoscope. Only a small percentage (less than 10%) bleed through their nose (epistaxis). A diagnosis of IAD is often made by visualizing excess secretions or mucus in the trachea post exercise. Affected horses may also cough intermittently. Several studies have shown that up to 95% and 65% of racehorses show signs of EIPH and IAD respectively. Obviously, not all of these racehorses are poor performers. Therefore, the problem is determining whether or not the EIPH or IAD is severe enough to impair the respiratory function, i.e. blood oxygenation during exercise.

Photos courtesy of Dr. Ken Hinchcliff	Grade 0: No evidence of hemorrhage.
	Grade 1: Flecks of blood or a single short stream of blood extending less than a quarter of the tracheal (windpipe) length.
	Grade 2: One continuous stream of blood extending at least one half the length of the trachea or multiple streams of blood covering less than one third of the tracheal surface.
	Grade 3: Multiple streams of blood covering more than one third of the tracheal surface.
	Grade 4: Abundant blood in the trachea, completely covering the tracheal surface and pooling at the thoracic inlet.