🐴 Diagnosing Asthma in Horses: Accurate Testing & Biomarkers in 2025 💨🧬

By Dr Duncan Houston BVSc

Equine asthma—formerly known as heaves, COPD, or recurrent airway obstruction—is a chronic, inflammatory lung disease that affects performance and comfort in horses. In 2025, diagnostic tools are improving, offering veterinarians new ways to differentiate asthma from infection and guide proper treatment. 🧠🐎

💡 Why “Asthma” Now?

What we used to call:

• 😤 Heaves
• 🫁 Chronic obstructive pulmonary disease (COPD)
• 🔁 Recurrent airway obstruction (RAO)

…is now grouped under the term equine asthma. This shift aligns with the condition’s human counterpart and helps classify it by severity:

• 🟢 Mild asthma: Reduced performance, occasional cough
• 🟡 Moderate asthma: Persistent cough, exercise intolerance
• 🔴 Severe asthma: Labored breathing at rest, pronounced respiratory effort

Just like in humans, symptoms range from subtle to life-threatening. 🔬

📋 Symptoms to Watch For

Common signs include:

• 💨 Increased respiratory rate and effort at rest
• 🔁 Chronic cough
• 📉 Poor performance, especially in heat or dust
• 🧪 Nasal discharge

Asthma is often misdiagnosed as a bacterial infection, which is problematic because steroid treatment can worsen infectious disease. Accurate diagnosis is essential. ⚠️

🧪 Current Diagnostic Gold Standard

The most definitive test is a bronchoalveolar lavage (BAL):

• 💉 A sedated horse has a small tube placed into the lower airway
• 💧 Sterile saline is introduced, then aspirated
• 🔬 The fluid is analyzed for inflammatory cells (eosinophils, mast cells, neutrophils)

BAL allows precise grading of inflammation and helps guide the right therapy. 🧠

🧬 New Research: Blood Biomarkers

Dr. Jean-Pierre Lavoie and colleagues in Canada are developing a blood-based test for asthma using biomarkers. Findings include:

• 🧪 Three biomarkers have been identified
• ✅ The test correctly rules out asthma in 100% of healthy horses
• ❌ The test only detects asthma in 57% of affected horses

This makes it a valuable screening tool—especially for excluding asthma before prescribing corticosteroids. 💡

📉 Why This Matters

Treating a respiratory infection as asthma can lead to:

• 💊 Inappropriate steroid use
• 🦠 Suppressed immune response
• 📉 Worsening infection and delayed recovery

That’s why knowing what you're dealing with before you treat is so critical in respiratory medicine. ⚖️

💊 Treatment Options After Diagnosis

✅ Mild to Moderate Asthma:

• 🌾 Environmental management (low-dust bedding, soaked hay)
• 💨 Inhaled bronchodilators or corticosteroids (e.g., fluticasone)
• 🧘 Minimized exposure to molds, dust, ammonia

✅ Severe Asthma:

• 💉 Systemic steroids (e.g., dexamethasone)
• 💨 Nebulization or inhaler-based therapy
• 📋 Strict stall management and turnout in dust-free zones

Every horse is different—so diagnostics should guide therapy, not guesswork. 🧠

📲 Ask A Vet for Respiratory Testing

If your horse has a chronic cough, exercise intolerance, or noisy breathing, visit AskAVet.com or use the Ask A Vet App to get support with asthma diagnosis and management. 📱🐴

Dr Duncan Houston and the team can help review BAL results, arrange biomarker testing, and recommend inhaled medications or dust control strategies. 💬🧠

🏁 Final Thoughts

In 2025, diagnosing equine asthma is easier and more accurate than ever—but it still requires precision. Whether using bronchoalveolar lavage or emerging blood biomarkers, getting the diagnosis right ensures the right treatment—and helps your horse breathe easier. 💨❤️

Need help confirming asthma or managing cough? Visit AskAVet.com to get a respiratory workup today 🐴🧬