McKee-Pownall Equine Services | Health Care FAQ

Health Care FAQ

What is Chronic Obstructive Pulmonary Disease (COPD)?

COPD is a relatively common cause of coughing and nasal discharge in stabled horses.

In long standing cases the horse may have difficulty in breathing and its chest and abdomen can be easily seen to move, hence the old name 'heaves'. Another name for this condition is "reactive airway disease" or "RAO".

What is COPD ?

COPD is a disease of the smaller airways (bronchioles and alveoli) in the lungs caused by an allergy to small dust particles and spores that are inhaled by the horse when he breathes.

Cause of COPD

Fungal spores and/or pollen dust are most important in terms of allergic 'trigger' factors. Previous viral and bacterial infections in the lung can predispose a horse to this condition.

The allergic reaction in the airways results in the production of fluid and thickening of the walls of the small airways of the lungs, causing their obstruction. This means that the horse has to make an increased effort to breathe and he develops a cough to clear trapped mucus.

Not Cureable

The pathology that occurs in the horse's lungs, except perhaps in the very early stages, is not reversible and so it is important to understand that this is a progressive condition. It cannot be 'cured' but the progress of the disease can be halted and the horse can be helped to accommodate to it.

What are the Symptoms of COPD?

Early Cases

In early cases, the only clinical sign may be a slight nasal discharge or dry cough that may go unnoticed. If untreated, the horse may start to find faster work more difficult. The cough will become more noticeable. As the disease progresses, the horse will cough with only slight exercise.

Severe Cases

In severe cases, the horse will have difficulty breathing even at rest, causing increased respiratory rate and effort. In very long-standing cases, the horse has to make a double effort to breathe out, using both the chest and abdominal muscles, developing a noticeable 'heave line'. These horses used to be called 'broken winded'.


Symptoms are often mild for years and only progress slowly with age. In some horses, however, acute attacks of respiratory distress accompany a repeated exposure to dust or pollens. This means that the condition may be seasonal (especially when associated with crops such as oil seed rape) or associated with stabling or feeding conditions.

What Causes COPD to Develop and How is it Diagnosed?

For a horse to show signs of COPD, he must have developed an allergy to inhaled dust, spores or pollen. A horse may be allergic to pollen but not spores or visa versa.

Fungal Spores and Pollen

Fungal spores are present in hay and straw, mouldy bedding or feed, and other organic material.

Pollens are found just about everywhere but levels in the air fluctuate greatly with season, location and weather conditions.

As with human hay fever, the higher the spore count in the air, the worse the condition becomes. Air quality in stables is therefore important for continuing equine health.


The diagnosis of COPD is based on history, management conditions and clinical signs.


Endoscopy ('scoping') and the collection of samples for microscopic examinations via bronchoalveolar lavage (BAL) help to distinguish between COPD and other causes of chronic cough such as infection. Infection may, of course, be a secondary complication of COPD.

What Treatments are Available?

Early Stages and Mild Case

Many early stage cases respond to changes in management, which remove the cause of the allergy:

  • Horses with COPD should be kept on 'dust-free' management, designed to keep environmental dust and spore levels as low as possible
  • Bedding should be paper, shavings or other non-organic material and should be kept scrupulously clean
  • Hay should be soaked before being fed or haylage should be used
  • 'Dry' feed should be fed dampened to reduce dust
  • Horses should be stabled away from other horses bedded on straw and away from hay and straw stores, muck heaps and other sites where dust and moulds may be produced
  • The need for good air quality and efficient ventilation cannot be over emphasized
  • Horses affected out of doors by pollens should be moved from high pollen areas until the season has passed

Long-Standing and Severe Cases

More severe or long-standing cases often require medication. Medicines that dilate the airways (bronchodilators) such as clenbuterol or cromoglycate may be given and corticosteroids can be used to reduce the allergic reaction.

These medicines may be given by mouth, by injection or by inhalation using an aeromask. Many cases require long-term treatment.

Allergy desensitization treatments are successful in some cases although it can be difficult to know exactly what agent a horse is allergic to. Blood tests can be performed to determine particular allergens and custom serum can be generated from this test.

Best Advice

Good management is the key to owning a horse with COPD.

Maintaining a clean, dust-free, well-ventilated environment, correct storage and maintenance of feeds and bedding and the use of hypoallergenic bedding materials all help reduce the incidence and the severity of this chronically incapacitating condition.