When breathing becomes difficult – COB, COPD, or RAO?

There are various terms used to describe this group of conditions. A central feature of all these terms is the obstruction (narrowing) of the small airways, which leads to breathing difficulties and coughing.

In English-speaking countries, the umbrella term “Chronic Obstructive Pulmonary Disease” (COPD) is frequently used, based on the assumption that the changes affect not only the bronchi but the entire lung. In German, the term “chronic obstructive bronchitis” (COB) is most commonly used. In veterinary medicine for horses, however, a distinction is typically made only between “Recurrent Airway Obstruction” (ROA) and “Inflammatory Airway Disease” (IAO).

The causes of chronic coughing in horses are varied, and the exact mechanisms are not yet fully understood. Initial triggers can include acute respiratory infections caused by viruses, bacteria, or lungworms. The mucous membranes of the respiratory tract swell, and increased mucus production occurs, which can no longer be properly cleared. Breathing becomes difficult due to the narrowing of the small airways. The horse attempts to cough up the excess mucus. Other causes include environmental allergens that come into contact with the horse’s lungs. These include mold, pollen, mites, and hay or straw dust. Horses whose airways are already weakened by an infection are particularly susceptible. Harmful gases, such as poor stable air with excessively high ammonia concentrations, can also act as a physical irritant and lead to impaired lung function. Another factor may be a lack of exercise, as the lungs’ self-cleaning mechanism is not sufficiently activated without adequate physical activity.

Two factors cause the small airways to narrow. The irritants described above lead to increased production of bronchial mucus. At the same time, the ability of the cilia (the tiny, moving hairs) to clear away the increasingly thick mucus decreases. Additionally, the airways become hypersensitive to certain stimuli, leading to a spastic overreaction of the small bronchi. Without veterinary treatment, irreversible damage to the lung tissue can occur, making normal lung function impossible. Due to the increased formation of connective tissue between the alveoli, the lungs permanently lose their elasticity. This is referred to as pulmonary fibrosis. The term "dampness," which is nowadays incorrectly used for any respiratory disease, strictly speaking describes only the final stage of RAO, which is characterized by pulmonary emphysema—the overinflation and destruction of the alveoli.

In the early stages, the only noticeable symptom is sometimes a mild cough, which may occur only at the onset of exertion. In some cases, the horses also have nasal discharge. This is watery at first but may later become whitish-yellowish. Affected horses show reduced stamina and tire more quickly. Even at rest, a significantly increased respiratory rate is noticeable, sometimes accompanied by audible breathing sounds. In advanced cases, shortness of breath and fever may occur.

Breathing is visibly difficult for affected horses; their respiratory muscles must work much harder than those of a healthy horse. When the abdominal muscles are also actively used to assist exhalation, an indentation becomes visible between the rib cage and the abdominal muscles. This so-called “steam groove” is familiar to most horse owners and indicates a severe respiratory problem. The high energy expenditure required for breathing therefore leads to weight loss in the horse if the condition persists for a long time. So don’t let time slip by unnecessarily if your horse is coughing; instead, contact a veterinarian right at the onset of the illness to correctly identify the cause.

A detailed history is essential for your veterinarian to make an accurate diagnosis. This means they need to know exactly when and how your horse is coughing, how it is housed, and whether there have been any changes in its housing or feeding conditions. During the examination, your veterinarian will listen to your horse’s lungs and may also percuss them. If the symptoms are not yet very clear at the beginning, it may be necessary to listen to your horse again after exercise or respiratory stimulation. To confirm the diagnosis, additional examination methods may be used: X-rays, blood gas analysis, or endoscopies of the respiratory tract can sometimes even be performed in the stable. Samples taken during these procedures are then examined in the laboratory.

Even though RAO is generally considered incurable, the first step—in addition to medication—is to reassess your horse’s housing and feeding regimen and adapt it to the condition. It’s important to note that even if symptoms subside, the hypersensitivity of the bronchial tubes persists and will affect your horse for the rest of its life.

The primary focus should always be on optimizing air quality for your horse. Simply reducing all dust-generating factors can lead to a significant improvement in symptoms. For stabled horses, low-dust bedding should be chosen, and only wet hay or haylage (i.e., compressed, lactic acid-fermented, airtight-packed hay) should be fed. Stalls with windows, paddock stalls, or ideally year-round open-stall or exercise-stall housing with optimal fresh air supply are preferable for RAO horses.

Another essential aspect of treating a chronically coughing horse is continuous exercise, as this is the only way to clear mucus from the bronchi and lungs. Free movement is at least as helpful as targeted lunging, riding, or walking. Always ensure a moderate exercise program, as your horse is still sick and should not overexert itself.

Medication aims to relieve bronchial spasms, thin the thick mucus, and help clear it from the bronchi. Mucolytics, as well as antispasmodic and bronchodilator medications, are the preferred treatments for this. Inhaling certain medications can help thin the thick bronchial mucus. Your veterinarian will create a detailed treatment plan for your specific case and can digitally send the medications for your horse to petsXL. This way, you’ll find all upcoming medication doses in your timeline and can set reminders for yourself.

While these measures and treatments cannot cure the condition, they can keep it well under control. Maintaining optimal living conditions remains the top priority. Only then can your horse breathe deeply again and enjoy life to the fullest alongside you.