Equine Respiratory Disease: The Killer In your Horse’s Stable

May 4, 2018 | Horse Health in the Stable

In our Bedmax Equine Health survey, respiratory disease emerged as by far the most common equine health problem experienced by horse owners during the winter months when most horses spend the longest periods each day in their stables…

Our survey is absolutely in line with all the veterinary research evidence produced in recent years that confirms that the biggest equine health challenge is respiratory disease.

This is crucially important, because a healthy respiratory system is absolutely fundamental to your horse’s overall health, wellbeing, fitness and performance.

Horses are nasal obligate breathers, which means that, unlike humans, they can inhale air only through the nose. A horse at rest will inhale approximately three to four litres of air in each breath. A horse exercising needs up to ten times this amount of air to function properly. Oxygen in the inhaled air is absorbed in red blood cells which in turn ‘power’ the horse’s muscle function – including the muscle movement required to breathe in and out.

The horse’s lungs are its engine. Oxygen is the fuel. The lungs transfer oxygen into red blood cells which it turn fuel the horse’s muscles. Contamination such as dust and spores in the fuel reduces the lungs’ capacity to power the muscles, compromise the engine’s performance and may cause serious, permanent damage.

The equine respiratory system has a series of filtration or defence systems to trap and expel particles in the nasal passages, but when substantial amounts of airborne particles such as dust and spores are present in the horse’s breathing zone, some of these will be carried into the respiratory system through the windpipe and into the lungs.

The smaller the particles, the deeper into the airways they will penetrate, and the deeper they penetrate, the greater the potential damage they will cause to the respiratory health of the horse.

Outside in a field or paddock, airborne dust disperses and horses can move away from concentrations of dust to find clean air.

Confined in a stable, a horse may not be able to avoid concentrations of dust and spores. Worse still, it is very often our management of the stable environment that creates potentially harmful concentrations of dust and spores in the first place.

What kind of damage can dust cause?

It is now very clearly established that relatively low levels of airborne dust, spores, and ammonia present in the air in the confines of a stable can cause the various levels of respiratory problems reported in our survey. These range from mild inflammation to allergic reaction and, in the most serious cases, chronic (incurable) pulmonary disease such as RAO – Recurrent Airways Obstruction.

In its mildest form, respiratory ill-health caused by irritation or allergic reaction to dust and spores may result only in some temporary inflammation of the upper airways. The tissue lining the respiratory system will become inflamed and swollen as blood rushes to these areas and mucus forms around the invasive matter. The horse may cough to expel this mucus. This reaction narrows the airways and restricts the volume of air that can be inhaled.

In its worst form – RAO – penetration of the deepest areas of the lungs by the smallest (microscopic) particles of dust or spores, or bacterial, fungal or viral infection, will cause restrictive inflammation and drastically restrict the horse’s capacity to breathe, raising its temperature significantly, clogging the respiratory system with mucus, and causing severe distress. The symptoms will include coughing and substantial discharges of mucus, sweating and severely laboured breathing, sometimes referred to as ‘the heaves’.

The worst forms of respiratory disease are ‘chronic’ or incurable conditions that will at best end the horse’s active career and could at worst end its life.

Do you know if your horse has respiratory disease?

Our survey showed that 13% of the 1040 horses whose owners responded had suffered from respiratory ill-health that required veterinary treatment and/or box rest.

A veterinary research report published in 2007 estimated that between 10% and 17% of all horses in the UK suffer from respiratory disease, but in older horses (aged 8 or more) this incidence could be as high as 30% – 50%. (Hotchkiss et al.)

The problem is likely to be much more widespread than our survey results have shown, but in many horses the disease may not at first be detectable.

Other studies have demonstrated that even horses that show no clinical symptoms (coughing, discharge etc) may reveal internal signs of respiratory disease when their lungs are examined with an endoscope, or ‘scoped’.

Veterinary experience also suggests very strongly that horses may have respiratory illnesses but show no obvious clinical symptoms.

In mild cases of respiratory problems, horses may show non-clinical signs of ill-health such as listlessness and lack of energy. Alert and experienced owners will sense that their horse is feeling under par and notice a downturn in their performance. But there could be other factors that might account for this, and even canny owners may not realise that their horses are developing a respiratory problem.

Unfortunately, a mild respiratory problem that goes undetected and untreated can turn into something as serious as RAO.

This means that owners may ‘inherit’ a latent case of respiratory disease in a horse thay have recently bought, which then escalates into a more serious problem. Or, just like a human, a horse may develop or contract a respiratory disease that shows no clinical symptoms until an escalation is triggered by a significant change in environment, an infection, or possibly simply by age.

How do you treat respiratory disease?

Veterinary treatments for respiratory disease are limited to the administration of drugs by mouth or by inhaler, and extended box rest to restrict movement to a minimum.

In serious cases of RAO, this treatment can only alleviate the symptoms, but cannot ‘cure’ or eradicate the underlying cause.

But in prescribing box rest, which will involve the horse being confined to the stable for 24 hours and day over a period that might extend to several weeks, vets will insist on the absolutely vital need to ensure that the stable environment is kept as free of airborne dust and spores as possible.

The principal sources of airborne dust and spores in a stable are dry hay and bad bedding. If the owner is not already using haylage or wet/steamed hay and a dust free bedding, this is what the vet will recommend.

Any horse that requires treatment for respiratory disease will need to be kept in a clean stable environment not only during the period of box rest but permanently thereafter.

Preventing respiratory disease

Preventing respiratory disease is obviously infinitely better than having to treat it.

The cost of veterinary treatment even for a mild case is significant. Treatment will involve loss of use of the horse for several weeks in mild cases, and permanent loss of use in severe cases.

Much more importantly for the vast majority of horse owners, preventing respiratory problems from occurring in the first place saves your horse from the sometimes extreme suffering and stress that respiratory disease inflicts.

Air quality in the stable is of paramount importance, and ensuring it is down to good stable management:

  • The forage and bedding you provide should be free of dust and spores
  • Stables must be well ventilated
  • Horses should be removed from their stables when mucking out or replacing bedding

And the air in the whole vicinity of your horse’s stable must be equally clean. Research at the equine veterinary hospital in Edinburgh has shown that dust and spores in the air within 50 metres of a horse with respiratory problems can affect its respiratory health.

Bedmax – shavings made specially to help beat respiratory disease

Bedmax began developing a purpose-made shavings bedding specifically for horses in 1998. Our aim was to create a completely natural, top quality bedding that would help horse owners overcome the many equine health problems associated with keeping horses in the confines of a stable.

Our top priority then was to eliminate the ‘airborne’ dust and spores present in traditional beddings such as straw and by-product wood shavings that cause respiratory problems and disease.

It still is our most important priority to ensure that Bedmax and Littlemax are free of dust and spores, helping owners to create a stable environment that safeguards their horses’ respiratory health and wellbeing, and minimises the risks, costs and suffering of this key equine health threat.