The Coughing Horse

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Infectious causes of coughing include influenza virus and the commonest cause of infectious coughing herpes virus, also known as “The Virus” or “The Cough”.  Both are preventable by vaccination.  Bacterial causes of coughing include strangles (Streptococcus equi) and a variety of other bugs some of which commonly occur when the horse is immunosuppressed or “run down” after a virus.  There is now a vaccine available for Strangles:  See our client information sheet.  Bacterial coughs can be treated with antibiotics.  Lungworm is now a rare cause of coughing limited to horses grazing pastures shared with donkeys.  Roundworm larvae migrate through the lungs and may cause coughing in young stock.

Allergic airway disease is increasingly common in horses as in people and coughing is a major symptom.  Asthma tends to affect children more often than adults but in horses allergic coughing is more common in adulthood and tends to become worse as animals age.  Recurrent Airway Obstruction (RAO) is the correct term for most allergic airway disease in the horse although it is often still referred to as COPD. It is also known as ‘heaves’. It is most often an allergy to mould spores, which are present in all hay and straw (even the best quality bales!).  Summer pasture associated obstructive pulmonary disease (SPAOPD) is an allergy to pollen and is therefore seasonal.  However, a large proportion of horses with SPAOPD also suffer from RAO.  RAO commonly starts after a virus has damaged the airway so any coughing horse should be managed in a dust (mould spore) free environment.  Full time turnout to pasture achieves this well but avoid muck heaps and feeding dry hay in the field.  Shavings and soaked hay will control coughing in most stable RAO horses but some cases will require paper or hemp bedding and haylage.  Some RAO and all SPAOPD horses will require long-term medication.

Do I need the vet? 
This is a frequently asked question!  If the horse is well, coughing only occasionally with no nasal discharge and no in contact animals coughing, then rest and dust free management will help the horse recover quickly.  Infectious coughs, wheezing, thick nasal discharges, frequent coughing, animals off their food, a depressed demeanour, a raised temperature and coughs which have persisted or worsened all warrant veterinary attention.

Asking some background questions and performing a clinical examination will often produce enough evidence to support a diagnosis.  However, some cases require further investigation in order for an accurate diagnosis to be reached.  Our practice laboratory can carry out bacteriology, haematology and biochemistry and we have access to specialist facilities for serology and virus isolation.  We have an endoscope for examining the airways and are able to take aspirates and washes from the airway and lungs.  These samples can be examined for bacteria and inflammatory cells (cytology) and contribute to the diagnostic work up.  When bacteria are isolated they can be typed and sensitivity tests performed to help select the best antibiotic.

How is it treated?
In addition to the normal range of oral and injectable medications we frequently use equipment to enable drugs for treating the respiratory system to be administered directly to the lung.  In the past, a nebulizer and mask have been used, but more recently we commonly use a simple device known as a ‘spacer device’ or ‘AeroChamber’ to allow metered dose inhalers (MDI’s, commonly known as “puffers” or “inhalers”) to be effectively used in the horse for the first time. These are standard treatment for human asthma sufferers.

The spacer devices are often used for treating asthma in young children and can be very effective in horses. Inhalers that are the most effective are those containing anti-inflammatory steroids (e.g. ‘Flixotide’), muscle relaxants (e.g. ‘Seravent’) or a combination (e.g. ‘Seratide’). Once a horse or pony has started on steroid medication excellent results can be achieved by using the treatment constantly through the season on a ‘two week on, two week off’ basis.

Please ask your vet for more information on any of the above, and please refer to our information leaflet on the correct use of inhalers.