Summer Pasture-Associated Recurrent Airway Obstruction (SPARAO), often referred to as “heaves” or equine asthma, is one of the most significant chronic respiratory conditions affecting horses. While it can occur year round, a seasonal variation known as Summer Pasture-Associated Recurrent Airway Obstruction presents challenges during warmer months.
What is SPARAO?
SPARAO is triggered by increased exposure to allergens commonly found in pasture environments during spring and summer. These include pollen from grasses and trees, airborne mould spores and dust, all of which can cause hypersensitive reactions in affected horses. This immune overreaction results in inflammation, narrowing of the airways (bronchoconstriction), and mucus production, compromising the horse’s ability to breathe effectively.
Recognising the Signs
Clinical signs of SPARAO vary in severity but typically include persistent coughing (often worse during or after exercise), nasal discharge, and laboured breathing. A visible “heave line” may develop along the horse’s abdominal muscles due to the increased effort required to exhale. Other signs include reduced performance, exercise intolerance, and, in chronic cases, a poor coat condition.
Owners may not always associate these signs with pasture exposure, making education around this seasonal variant essential. A horse that performs well in winter may suddenly begin showing signs of respiratory stress when turned out during peak pollen times.
Veterinary assessment is vital for accurate diagnosis. This often involves a clinical history, endoscopy, and diagnostic procedures such as bronchoalveolar lavage (BAL), tracheal wash (TW) and blood tests. These help identify airway inflammation and exclude other potential causes. Treatment plans typically combine medical intervention with targeted management strategies.
Management is the cornerstone of controlling SPARAO. Practical steps include:
- Limiting turnout during high pollen or dusty periods
- Providing dust-free forage, such as soaked or steamed hay
- Avoiding straw bedding and choosing low-dust alternatives
- Keeping stables ventilated and clean
- Using air purifiers or misting systems to reduce airborne allergens
- Modifying exercise regimes to avoid peak allergen times
While these steps help reduce allergen exposure, they can be difficult to implement consistently, particularly during dry, high-risk periods.
The Role of Nutritional Support
Nutritional supplements designed to support the respiratory system can play a vital role in a multifaceted management plan. Research supports the use of natural antioxidants to help neutralise oxidative stress in the lungs and maintain clear airways. Supplements formulated for respiratory health; particularly those including antioxidants, herbs, and essential oil, can help reinforce natural defences and maintain respiratory comfort.
Thanks to NAF
This blog was prepared by NAF Equine. You can shop NAF products at RB Equestrian.
In June 2025 we have 20% off NAF Five Star Respirator Boost (500ml, 1 litre and 2 litre options). Respirator Boost helps maintain open airways and targets respiratory functions quickly.
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