The horse is an obligate nasal breather, this means horses breath solely through their nose. Air passes up through the nostrils and nasal passage, into the naso pharynx, through the larynx and down along the windpipe to the lungs. Horses possess a large lung capacity, which can increase airflow up to 20 times their resting value during exercise. A resting horse breathes on average of 15 times per minute, moving approximatley 5 litres of air with each breath. During fast work a horse can move up to 1,500 litres of air per minute through the respiratory system .
The breath, along with fitness, can be compromised if obstruction to the airway occurs. Two examples of respiratory diseases that can affect the horse’s health and performance, but can be made manageable, are Recurrent Airway Obstruction (RAO) or Exercise Induced Pulmonary Haemorrhage (EIPH).
RAO is the new term for what was previously known as Chronic obstructive pulmonary diease (COPD). RAO is essentially a horse’s allergic reaction to environmental dust. This allerigic reaction causes inflammation and narrowing of the airways making it difficult for the horse to breath.
This allergic reaction can be caused by fungal spores, found in dusty bedding or mouldy hay and straw. The allergic reaction causes an increase in the mucous production, along with inflammation constricting the airways. This combination makes it harder for the horse to breath as the airway narrows. Sometimes, the airway may completely collapse during expiration, which makes breathing out difficult for the horse.
Symptoms of Recurrent Airway Obstruction:(RAO)
- Excess mucus
- Reduced exercise tolerance
- Increased respiratory rate
Once diagnoised RAO is a lifelong condition, but in some cases can be made manageable by the use of equine feed supplements. And the cause can be completely eliminated by turning the horse out full time. If this is not possible a dust free environment must be made available using dust free bedding and mould free forage. The horse may be prescibed a bronchodilator or corticosteroids to help with inflammation and acute attacks of RAO. Equine health supplements can help to loosen mucus, elminate coughing and open up the airway.
Other such Equine Respiratory conditions that affect performance is Equine Induced Pulmonary Harroehage (EIPH) – also known as lung bleeding. It is associated with exercise and refers to bleeding in the lungs due to exertion. EIPH can be seen in varying degrees of hemorrhage that come from the nostril. Horses may cough following bleeding or freqeunt swallowing may occur, and/or the horse may show poor performance. A more definite diagnosis can be made by endoscopic examination of the trachea. Because EIPH occurs in horses in varying degrees a combination of these techniques can be carried out to achieve an accurate diagnosis. Another test used is a broncho-alveolar lavage (BAL), which is used to confirm the presense of EIPH when there is a lack of blood in the trachea. Once diagnoised, managment is essential to prevent recurring episodes of EIPH. Similar to RAO, the environment should be made as dust free as possible. Exercise and conditioning should be planned and time taken to reach fitness.
Equine supplementing can also be part of the management programme for these respiratory issues, to open up airways, eliminate coughing and help the horse to perform better.