The Horse's Respiratory System

Seasonal respiratory conditions are frustrating, and sometimes the cause is never identified. 

Stabled horses are subjected to a constant respiratory challenge from fungal spores and dust in their immediate environment, and even horses living out can still be affected.  In fact, respiratory problems are the second-leading cause of exercise intolerance and poor performance in athletic horses, following musculoskeletal disorders. It has been estimated that up to half of all stabled competition horses may have some degree of respiratory disease! 

At this time of year, whether the horse is stabled or turned out 24/7 there are multiple things that can affect your horse. Is it dusty stables when he’s kept in? Or the pollen outside when he’s in the paddock? Something in the hay? All questions we ask ourselves and wonder what we can do to help support our horses.

Why is my horse coughing? 

In a healthy horse, inhaled particles such as dust, tiny plant particles, fungal spores etc, are usually trapped in the sticky mucous layer in the upper airways, and then tiny hairs waft this mucous upwards where it is swallowed rather than inhaled, and so does not reach the lungs. This process is known as the muco-ciliary escalator.  In a horse where this function is compromised, the respirable particles can travel right into the lower airways and set up an inflammatory response where the mucous gets thicker, and harder to move, the hairs can be damaged and the airways are narrowed – so the horse coughs in an attempt to open the airways.

The horse’s lungs are the 3^rd largest organ in a horse’s body (in case you are wondering, the skin is the largest and the digestive system is the 2^nd largest!). 

The main function of the horse’s respiratory system is to bring oxygen from the air (inhalation) into the lungs where it is then passed through gradually smaller and smaller airways in the lung, until it reaches the end sacs, called alveoli, deep in the lungs.  The alveoli have very, very thin membranes, about 100^th the width of a human hair which allows the oxygen to pass from the alveoli into the red blood cells carried by the tiny blood vessels or capillaries which surround the alveoli. The waste product carbon dioxide goes in the opposite direction – back from the blood into the lungs where it is exhaled or breathed out. 

The blood system then carries the oxygen all around the body and collects the waste carbon dioxide to take back to the lungs to be exhaled. Oxygen is needed by almost every living cell in the body to work properly and produce energy, so a correctly working respiratory system is vital for health, wellbeing and performance in all horses and ponies. 

In addition, the respiratory system performs other important roles in the body, including helping to regulate body temperature, and has various ways to protect the body from inhaled dust, bacteria, viruses, fungal spores and other particles.

Horses are obligate nasal breathers – they can only breathe through their nose, even when they are in respiratory distress.  

At rest, horses typically take around 12 breaths per minute, and this moves about 5 litres of air per breath -or about 60 litres of air moved in and out of the lungs each minute. A typical bucket holds 15 litres, so the horse moves 4 buckets of air in and out of his lungs each minute at rest. 

During exercise, the horse needs more oxygen for muscles to work harder, and so will start to breathe more quickly to get more oxygen in to the lungs. 

However, once the horse starts to canter or gallop, they begin to breathe more deeply, and in perfect time with their stride, so as they increase their stride length to go faster, they breathe more deeply to obtain more oxygen. At galloping speeds, the horse may be breathing twice a second, and moving up to 15 litres (I bucketful) every breath! The exhaled air from a horse’s nostrils at gallop can be travelling at around 60 litres per second – more than most fire hoses!

How can I minimize my horses’ respiratory challenges? 

• Increased turnout if stable dust is a problem, whereas horses affected by pollen may benefit from some time in the stable, where their exposure to the pollen is reduced. 
• Soaking the hay to reduce the burden of inhaled particles (which include fungal spores, plant debris, bacteria etc) will help, and where possible, complete soaking for around 30 minutes in clean water will remove a significant proportion of the respirable particles. If you were soaking to remove more of the soluble carbohydrates, it would take longer.
• Change of bedding may be needed if it’s become dusty.

Are there supplements I can feed to support the respiratory system of my horse? 

The Equine America respiratory range is widely and successfully used by horses of all ages and types, suffering with varying respiratory issues, and encompasses two approaches:

Coff Less, Ventilator and Pollen-Eze are all powders added to daily feed and provide a blend of natural herbs and phytochemicals (active compounds from plants), including astragalus, fenugreek and nettle, known for their role in helping to maintaining respiratory function. In addition, the echinacea and MSM help to support the immune system, and eucalyptus and apple cider vinegar are recognized to have broncho-dilatory properties and help keep the airways open. 

Alternatively, Airways Solution provides high levels of menthol, eucalyptus and peppermint, and can, if required, be used alongside Coff Less to provide a short term boost of broncho-dilatory ingredients, for both leisure and performance horses before a key event or activity, when the environment is particularly challenging – a high pollen count day, or if a horse who was otherwise turned out 24/7 needed to be stabled for any reason.

Airways solution can be syringed for rapid effect (subject to Governing Body rules and regulations) or can be offered daily in the feed.

There is also some interesting research concerning the importance of Vitamin C in lung health, and although the horse should make his own vitamin C, there are occasions where requirements increase, and ability to synthesis his own vitamin C may be compromised or reduced, such as horses in intense work who travel frequently.  Vitamin C 2000 powder will provide additional support for lung health in these cases.

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