Diagnosing EIPH

When faced with an EIPH diagnosis, understanding the range of diagnostic tools available can help you and your veterinarian assess and manage the condition effectively. Almost all horses experience some degree of lung bleeding during intense exercise. For most, it’s mild and may not affect performance. Recognizing EIPH as a common issue in athletic horses can make the diagnosis feel more manageable, though assessing severity is essential.

HERE'S WHAT TO KEEP IN MIND: 

If your horse is one of the rare (<5%) of horses that have shown blood after exercise, you will want to rule out other causes. If you see blood from the nostrils, confirm its source since nosebleeds can also stem from other issues like trauma, ethmoid hematomas, sinus tumors, or guttural pouch infections. These require different treatments and shouldn’t be confused with EIPH.

If your horse is like the majority horses, they will not show external evidence of bleeding.

CURRENTLY USED DIAGNOSTIC TOOLS

1. ENDOSCOPY

  • The "Gold Standard" Test: Endoscopy involves inserting a small camera into the trachea to check for blood and mucus in the airways. It’s best done within 30-120 minutes after exercise to detect bleeding accurately.
    • Timing is Crucial: Bleeding can be delayed or isolated, sometimes leading to false negatives with endoscopy if not detected in the trachea right away. Using a 3m versus a 1m scope to reach the bronchi and bronchioles improves detection, or repeating the scope three times on different days improves reliability of diagnosis. Also, hemorrhage can occur for up to 20 hours post-exercise.
    • Grades of EIPH & Inflammation: Your veterinarian may discuss the EIPH grade, as well as inflammation grade (based on mucus), which can guide treatment and management. EIPH is graded 0-4.

The 4 grades of increasing severity found on tracheobronchoscopic examination for EIPH are: 

Grade 0: No visible blood in the airways.

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 Grade 1: Small flecks or short, thin streaks of blood covering less than 10% of the airway surfacegrade1.png

Grade 2: Longer streaks (over half the trachea's length) or multiple short streaks covering less than one-third of the airway. 

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Grade 3: Multiple streams of blood covering more than one-third of the airway, without pooling where the trachea enters the chest.

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Grade 4: Blood covers over 90% of the airway and pools at the point where the trachea enters the chest.

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2. TRANSTRACHEAL WASH AND BRONCHOALVEOLAR LAVAGE

  • Transtrachael Wash (TTW) is a procedure that collects sample of fluid from through a horse’s trachea to detect blood or inflammatory cells, helping to confirm lung bleeding and the presence of a secondary bacterial infection. Typically a long plastic catheter is passed through a large needle inserted between the cartilage rings of the trachea and saline is injected from a syringe and then withdrawn back into the syringe for examination.
  • Bronchioalveolar Lavage (BAL or “Lung Wash”) is a procedure that involves washing the lungs of a horse with saline and collecting samples that most accurately assess bleeding severity and level of inflammation by counting red blood cells and white blood cells, respectively, as well as hemosiderophages — immune cell scavengers that are indicative of red blood cell clearance and breakdown from previous episodes. This technique also catches those mild “bleeders” that may be missed by scoping. Typically a tube or small endoscope is passed through the nostrils in the lower airways and saline is flushed in and then sucked back out for examination under a microscope.

BAL is the most sensitive and accurate method for detecting EIPH. There is a weak correlation between the number of red blood cells (RBCs) detected in bronchoalveolar lavage fluid (BALF) and findings from endoscopy. This is because the standard 1-meter endoscopes often used in tracheobronchoscopic examinations often cannot reach the smaller airways of the lungs. Use of a 3-meter endoscope improves the accuracy and sensitivity of endoscopy, especially when performed 30 minutes to 2 hours after exercise.

3. IMAGING TECHNIQUES

  • X-rays, Nuclear Scintigraphy, and Ultrasound: These imaging methods provide non-specific details about lung health and abnormalities. While not definitive for EIPH, they can give a fuller picture of any underlying issues.

4. BLOOD BIOMARKERS

  • Additional Insights: Biomarkers found in the blood such as angiotensin converting enzyme (ACE) that have been associated with EIPH, as well as haptoglobin, secretoglobin, surfactant protein D, and serum amyloid A that are linked to equine asthma, can help detect hemorrhage and inflammation, respectively, adding another layer of understanding to your horse’s diagnosis.

5. COMBINATION OF DIAGNOSTIC TESTS

  • Why Multiple Tests? No single test can capture the full scope of EIPH. Combining diagnostics gives a clearer picture of bleeding severity, inflammatory impact, and the potential of airway obstructions and heart issues to contribute to lung bleeding if they are present. Overground exercise endoscopes may help to identify clinically relevant upper airway obstructions including dorsal displacement of the soft palate and laryngeal hemiplegia that impact airway resistance and thus EIPH. Exercising or immediate post-exercise electrocardiograms can identify atrial fibrillation, a cardiac arrhythmia, that can exacerbate EIPH. Cardiac ultrasound can identify leaky valves and other functional abnormalities that may impact EIPH levels.

By understanding the diagnostic options and working closely with your veterinarian, you can get a well-rounded view of your horse’s condition. This comprehensive approach allows for an informed management plan to help your horse perform its best, even with an EIPH diagnosis.