HORSES · Condition guide
Equine asthma: real veterinary case reports
Equine asthma is now the unifying term for the inflammatory airway diseases historically called heaves, RAO (recurrent airway obstruction), and IAD (inflammatory airway disease). The cause is hypersensitivity to inhaled environmental allergens — hay dust, mould spores, and stable dust are the worst offenders. Stabled horses are most affected; pasture-kept horses can develop a summer version (summer-pasture-associated RAO) from pollen and mould.
Mild cases (IAD) cause cough, mucus, and reduced performance without obvious dyspnoea at rest. Severe cases (RAO/heaves) show an unmistakable 'heave line' (hypertrophied abdominal muscles), increased respiratory rate and effort even at rest, and dramatic exercise intolerance. The cornerstone of treatment is environmental modification — soaked or steamed hay, low-dust bedding, and as much turnout as possible. Inhaled corticosteroids and bronchodilators are highly effective adjuncts.
What vets typically check for
- History and clinical exam — heave line, nostril flare, increased abdominal effort.
- Endoscopy of upper airway and trachea — check mucus accumulation and lower airway secretions.
- Bronchoalveolar lavage (BAL) — confirms airway inflammation and rules out infection.
- Environmental management: soak or steam hay, dust-free bedding, maximise turnout.
- Medical therapy: inhaled fluticasone or systemic dexamethasone; bronchodilators (salbutamol) for crises.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Equine asthma (RAO/IAD). Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- Successful Treatment of Acute Respiratory Distress Syndrome in an 8-Day-Old Standardbred Foal With Intratracheal Oxygen Therapy via Temporary Tracheostomy.
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001) · 2026 · United States
An 8-day-old Standardbred filly was brought in for severe breathing problems and diagnosed with acute respiratory distress syndrome (ARDS). Initial treatments, including antibiotics and oxygen through her nose, didn’t help, so the veterinarians switched to a temporary tracheostomy, allowing for better oxygen delivery directly into her trachea. After 24 hours of this treatment,
- Iatrogenic aspiration pneumonia in six horses: A retrospective case series.
Journal of equine veterinary science · 2025
In a study involving six horses treated for a condition called iatrogenic aspiration pneumonia, which can happen when a horse accidentally inhales something like mineral oil, researchers looked at how these horses were affected and treated. The horses that were brought to the hospital quickly, within two hours, and received immediate treatment with water or water mixed with ele
- Multi-pathogen lower respiratory tract infection including a fungal agent in a yearling mustang filly.
The Canadian veterinary journal = La revue veterinaire canadienne · 2025 · United States
This report talks about a yearling mustang filly who had a serious lung infection caused by multiple germs, including a fungus, along with some blood issues like anemia (low red blood cells) and low platelet counts. To figure out what was wrong, the veterinarians used various tests, including imaging of the chest and special tests on samples from her lungs. They treated her wit
- Successful management of two horses with suspected pulmonary haemorrhage in recovery from general anaesthesia.
Veterinary anaesthesia and analgesia · 2025 · United Kingdom
Two horses, a 24-year-old warmblood mare and a 12-year-old Holsteiner gelding, underwent surgery while under general anesthesia. After their procedures, both horses experienced significant bleeding from the lungs, which is known as pulmonary hemorrhage. This bleeding was managed with medications and oxygen support, and both horses were able to recover and go home after treatmen
- Treatment of mycotic rhinitis caused by aspergillus fumigatus in a quarter horse mare using topical clotrimazole and oral potassium iodide.
Veterinary research communications · 2024 · Brazil
A 7-year-old Quarter Horse mare was brought in with a history of nasal discharge, bleeding, and difficulty breathing due to a fungal infection in her nose caused by Aspergillus fumigatus. After several tests, the vet started treatment with a topical antifungal ointment and potassium iodide. While the ointment showed some improvement, it had to be stopped because the mare develo
- Identification of asinine gamma herpesviruses in a donkey with interstitial pulmonary fibrosis, pleural effusion and thrombocytopenia.
Journal of equine veterinary science · 2024 · Italy
A 23-year-old donkey was brought in for severe breathing problems, suspected to be due to equine asthma. Tests showed significant lung inflammation and a bacterial infection, but despite aggressive treatment, the donkey sadly passed away within two days. A post-mortem examination revealed severe lung damage and fibrosis, which was linked to a herpesvirus infection. This case hi
Frequently asked questions
- Can equine asthma be cured?
- Not cured — but very effectively managed. Most horses with mild-to-moderate asthma can return to athletic work with environmental changes and judicious use of inhaled steroids during flare-ups. Severe RAO is harder, but full pasture management with no hay can produce remarkable improvement in many horses.
- Why does soaking hay help?
- Soaking hay for 10-30 minutes (or steaming) dramatically reduces the airborne respirable dust and mould spores that drive airway inflammation. Soaked hay must be fed within hours and not left to ferment.
- Are inhalers really practical for horses?
- Yes — equine-specific spacer devices (e.g. AeroMask, Equine Haler) allow inhaled fluticasone or salbutamol to be delivered effectively. Most horses tolerate the mask well after a brief introduction, and inhaled therapy avoids the systemic side effects of long-term oral steroids.