Wheezing in horses: causes and approach

What is wheezing and when is it a concern?

Wheezing is an audible, rattling or whistling sound that a horse makes during breathing, usually during exertion. An occasional wheeze after intensive work does not need to be immediately alarming, but if it occurs consistently — even at rest or during light exercise — there is probably something wrong. In healthy horses the airways breathe smoothly; resistance in the nose, throat or lungs causes the sound. Also watch for accompanying signs such as nasal discharge, coughing or reduced performance. Together these give a clearer picture than wheezing alone.

The most common causes

Respiratory problems in horses have a variety of causes. The most common are:

• IAD (Inflammatory Airway Disease): mild inflammation of the airways, often in young sport horses
• RAO/EHO (Recurrent Airway Obstruction): chronic hypersensitivity to dust and moulds, comparable to asthma
• Upper airway obstructions: such as laryngeal paralysis ('roarer'), where the larynx does not open properly
• Viral or bacterial infections: such as strangles (Streptococcus equi) or viral infections like EHV
• Environmental factors: poor stable air quality due to ammonia, dust from hay or bedding

Recognition: watch for these signs

In addition to the audible sound, there are more signs that indicate respiratory problems:

• Coughing during or after riding, sometimes also in the stable
• Nasal discharge: clear is less worrying than yellow or green
• Extended recovery period after exertion (heart rate still above 60 beats/min after 10 minutes)
• Swollen lymph nodes at the throat during infections
• Visible abdominal effort during exhalation ('heaves line') in severe RAO

Diagnostics: what does the vet do?

With persistent symptoms, a vet is essential. Common examinations include endoscopy of the airways (where the vet looks directly into the nose, throat and trachea) and bronchoalveolar lavage (BAL), in which fluid flushed from the lungs is analysed for inflammatory cells. If an infection is suspected, additional blood tests or a culture are carried out. A lung function test is possible but less commonly used in practice. The more information you gather beforehand — duration of symptoms, working conditions, stable environment — the more targeted the vet can work. In EquiSight you record this in the horse profile, so you don't forget anything during the consultation.

Treatment and management in practice

The approach depends on the diagnosis, but a number of measures help with almost all respiratory problems:

• Switching to fermented roughage (haylage or soaked hay) reduces fungal spores by up to 95%
• Rubber or wood shavings as bedding instead of straw reduces dust and ammonia
• Maximum ventilation in the stable: fresh air is more important than warmth
• Medication via inhaler (bronchodilators or corticosteroids) for RAO on prescription from the vet
• At least 4 hours of turnout per day speeds up recovery in cases of airway inflammation

Roarer (laryngeal paralysis) examined separately

Laryngeal paralysis, commonly known as 'roarer', is a specific condition in which the left vocal cord becomes paralysed and collapses into the airway during exertion. The characteristic whistling or wheezing sound is clearly audible at canter or during heavy work. It occurs more frequently in large breeds such as warmbloods and Thoroughbreds over 16 hands. Surgical intervention (prosthetic laryngoplasty or 'tie-back') is the most commonly used treatment and produces good improvement in 70–80% of cases. Without surgery, the condition almost always deteriorates.

Monitoring with EquiSight

Respiratory problems require consistent follow-up over a longer period of time. Record in the horse profile when you hear wheezing, during what type of exertion and under what circumstances. Use the calendar for vet consultations and treatment plans, and ask EquiCoach to recognise patterns in the data you are tracking. This way you can quickly see whether an adjustment to the stable environment or feed is having an effect.