Equine asthma is a respiratory disease in horses. It is similar to human asthma and is caused by allergic reactions to dust, mould spores and other airborne allergens. Studies emphasise the importance of environmental and management factors, including the quality of ventilation and feed management. This is because horses kept in well-ventilated stables with low-dust feed show fewer clinical symptoms and are less likely to develop asthma.
Symptoms
Equine asthma, also known as RAO (Recurrent Airway Obstruction) or COB (Chronic Obstructive Bronchitis), shows a variety of symptoms that can vary depending on the severity of the disease. The most important symptoms are:
- Cough
- Shortness of breath (dyspnea)
- Nasal discharge
- Reduced performance
- Loss of appetite
- Noticeable breathing noises and rattling noises
Causes
Equine asthma is caused by a variety of environmental and genetic factors. The main causes include:
- Allergens
Dust, mould spores and other airborne particles in the barn environment are common triggers. Hay and bedding can contain mould spores and endotoxins, which can trigger asthma in sensitive horses. - Environmental factors
Poor ventilation in stables increases the concentration of allergens and pollutants in the air, which increases the likelihood of respiratory problems. Stables with poor ventilation have a higher prevalence of mild to moderate equine asthma. - Genetic predisposition
Some horses have a genetic predisposition to respiratory diseases. These horses are more sensitive to environmental factors and are more likely to develop asthma when exposed to allergenic substances.
- Feeding and husbandry
Feeding round bales of hay with a high endotoxin and dust load is a known risk factor. - Infections
Previous respiratory infections can damage the airways and increase sensitivity to allergens, which increases the risk of developing asthma. - Macrophage activity
New research is investigating the role of macrophages, the immune cells that play a central role in the response to inhaled particles. These cells decide whether an immune response is required and their dysregulation can contribute to the development of asthma.
By managing environmental conditions, reducing dust and mould and providing adequate ventilation, many of the risk factors for equine asthma can be minimised.
Diagnosis
The diagnosis of equine asthma is a multi-faceted process involving both clinical observations and various diagnostic procedures to provide a comprehensive assessment of respiratory health. Firstly, we will take a thorough history to gather information about the horse's medical history, husbandry conditions and observed symptoms such as chronic coughing and breathlessness.
With the help of a blood gas analysis, for which we take a blood sample, we can determine the concentrations of oxygen (O2) and carbon dioxide (CO2) as well as the pH value. These parameters provide information about the efficiency of gas exchange in the lungs and the general respiratory function of the horse. A low oxygen content (hypoxaemia) and an increased carbon dioxide content (hypercapnia) can indicate a serious respiratory disease.
Bronchoscopy provides a direct visual assessment of the airways. A flexible endoscope is inserted through the nose into the trachea and bronchi to visualise mucus accumulations and other abnormalities and to enable mucus samples to be taken from the upper and lower airways. In addition, ultrasound examinations and chest x-rays can be performed to rule out other lung and respiratory diseases.
The diagnosis of asthma requires a careful and comprehensive assessment of the horse's state of health. Our clinic has the necessary technical equipment to ensure that the appropriate treatment measures can be initiated at an early stage.
Treatment
The treatment of asthma in horses aims to alleviate respiratory distress, reduce inflammation and improve the animal's well-being. Improving the stable environment is an essential part of the therapy. Low-dust bedding, and high-quality, low-dust hay or soaked hay can help to reduce the amount of inhaled irritants. Good ventilation in the stable is also crucial to minimise the concentration of allergens in the air.
Medications such as corticosteroids reduce the inflammation of the airways; they can be administered orally or by inhalation.
Inhaled therapies have the advantage that they reach the lungs directly and have fewer side effects. In addition, so-called bronchodilators can be used to widen the airways and make breathing easier. These medications work quickly and can alleviate acute symptoms.
For horses that react strongly to dust and mould spores, it can be helpful to shorten the stable stay and let the animals out to pasture as often as possible. In very severe cases, it may be necessary to wean the horses off hay completely and switch to a pelleted, dust-free diet.
In addition to these measures, it can be helpful to supplement omega-3 fatty acids, as they have anti-inflammatory properties. Regular veterinary check-ups and close co-operation with the vet are important in order to monitor the progress of the disease and adjust the therapy if necessary.
Through a combination of environmental management, medication and regular monitoring, many horses with asthma can lead a normal, active life.