Signs of EIPH

Exercise-Induced Pulmonary Hemorrhage (EIPH) can be a hidden problem—its signs aren’t always obvious. But don’t be misled; EIPH occurs across all levels of athletic performance, even during mild to moderate exercise. It can happen without visible blood at the nostrils or even hide from detection by tracheal endoscopy.

QUICK GUIDE TO RECOGNIZING INDICATORS THAT MAY POINT TO EIPH BEING A PROBLEM: 

1. NOSEBLEEDSnosebleed.png

  • Rarity: Observing a nosebleed is rare. However, if your horse lowers its head to eat or drink, blood may drain from the lungs and become visible at the nostrils. 

2. SWALLOWING AND COUGHING AFTER EXERCISE

  • Signs: Persistent swallowing or coughing post-exercise can indicate blood accumulation in the airways. Your horse may cough to clear the throat or swallow as blood is brought up from the lungs.

3. SLOWER RECOVERY TIME AFTER INTENSE WORKOUTS

  • Signs: An elevated respiratory rate and slow or extended recovery post-exercise may mean the lungs are struggling to provide adequate oxygen. This could indicate an underlying lung issue like EIPH.

4. DULL OR BURNT-LOOKING COAT CONDITION

  • Signs: Horses that bleed often exhibit a dull or "burnt" appearance in their hair coat.

5. RESPIRATORY DISTRESS AND BEHAVIORAL CHANGES

  • Signs: Look for signs of respiratory distress, such as raising or tossing the head, extending the neck, and resisting the bit. These behaviors suggest the horse may be trying to increase airflow or alleviate discomfort.

6. PERFORMANCE AND COMPETITIVE SUCCESS

  • Racehorses: Horses with mild EIPH (Grades 1-2) are 4x more likely to win and nearly 2 times more likely to place in the top three than those with moderate to severe EIPH (Grades 2-4). See the discussion below on “Endoscopy” for a detailed discussion of EIPH Grading.
  • Severe EIPH: Horses with severe EIPH (<15%) are less likely to win or place as a result of the blood negatively impacting performance and may have a shortened career due to cumulative damage to their lungs.
  • Barrel Racers: EIPH is positively correlated with run speed (i.e. ability) in barrel horses, although severe cases can still impact stamina. 

7. SIGNS OF EXERCISE INTOLERANCE

  • Immediate and Long-Term Effects: Severe bleeding episodes cause inflammation and swelling in the lung tissue, often leading to airway obstruction by blood and mucus. Repeated episodes contribute to cumulative lung scarring, progressively involving larger portions of the lungs. Scar tissue thickens the blood-gas barrier, and inflammation fills the airways with blood and mucus, while increased shear stress at the junctions between healthy and scarred tissue further aggravates bleeding. Together, these factors significantly reduce oxygen exchange efficiency and limit exercise tolerance. High inflammation levels can also lower the threshold for lactate accumulation, raise heart rate above 200 beats per minute more quickly, and increase overall lactate concentration—all of which impact athletic performance and hasten fatigue.
  • Indicators: If your horse suddenly loses focus or speed, stumbles, hits rails, or tires earlier than usual, this could indicate a significant bleed. Reduced lung function and oxygen deficit can lead to muscle fatigue and decreased performance. Common symptoms include stumbling, muscle cramps, and early-onset fatigue.

8. RARE BUT SERIOUS: SUDDEN DEATH

  • Possibility: Though rare, severe cases of EIPH can lead to sudden death.

Understanding these signs and monitoring them closely can help you identify EIPH early and keep track of its progression. Remember, even minimal bleeding can gradually affect lung health and athletic ability over time.