Startlingly, many horses that do not show the outward clinical signs of a respiratory disease could still be suffering on a sub clinical level which can impact on performance. Furthermore, as horses become fitter through training, heart and muscle function will improve but the respiratory system will not change and so respiratory function remains the limiting factor to exercise performance. This article will focus on the triggers for respiratory disease and what can be done to overcome them.
Researchers in Germany have found that in over half of 112 sport horses who were deemed perfectly healthy and not showing any outward signs of respiratory stress did in fact have respiratory disease after examinations using endoscopy and auscultation. This indicates that respiratory disease is more common than we may think. The main causes of respiratory disease can be allocated to the following sources:
- Infectious agents – viruses, bacteria and mycoplasma
- Allergic reactions – pollen, mould/fungi, dust/forage mites and bacterial toxins
- Irritant materials – ammonia, dust and cold air
- Other – anatomical dysfunction, exercise induced pulmonary haemorrhage, reactions to medications and pulmonary embolism or thrombosis
One of the first recognisable signs that a horse may have some degree of respiratory compromise is a cough. Some people believe that if a horse coughs a few times during warm-up for example that this is OK. This is however not OK and in such cases the situation should be investigated further by a vet. Horses cough in a very sporadic manner; often not at all for several hours which can easily be missed by the owner. Other external clinical signs can include one or more of the following:
- Nasal discharge
- Increased respiratory rate/effort at rest
- Increased temperature
- Abnormal breathing during exercise
- Slow recovery after exercise
- Frequent swallowing during exercise
- Blood at the nostrils after exercise
- Poor exercise performance
As with all disease, it is far better to prevent respiratory difficulties rather than treating them. There is a multitude of practises to adopt to principally improve the air quality both in the stable and in the immediate vicinity of the nostrils:
- Bedding – there are many types available nowadays to choose from but should be dust extracted.
- Flooring – should have a fall towards the rear of the stable allowing excess urine to drain away. If matting is used this should either be sealed to prevent urine building up underneath or regularly hosed down underneath and disinfected. As a general rule if you can smell ammonia in the stable then levels are high enough to cause irritation in the airways.
- Ventilation – good ventilation is a must.
- Management – Do not muck out with your horse in the stable as large amounts of respirable dust and ammonia will be released into the air.
- Feed – feed forage and bucket feeds from the ground to encourage head lowering to aid clearance of material from the airway.
- Forage – even well-made sweet smelling hay will have some degree of dust, mould and fungal spore contamination. Hay will also contain mites and their faeces. Soaking hay will cause the respirable irritants to swell to a size too large to cause respiratory issues; once the hay is allowed to dry these irritants will once again be present. Soaking hay will also cause precious water soluble vitamins and minerals to leach out and reduce the calorie content, increasing the reliance on bucket feeds to provide nutritional shortfalls. Steaming is another option which results in less loss of nutrients. Another choice is to feed well made, high quality haylage which should contain no moulds or fungus.
- Turnout – more time spent at pasture will help to reduce the incidence of respiratory disease.
- Vaccination – keep up to date with vaccinations especially if your horse comes into contact with a range of others.
- Travelling – minimise stress on the airways during long journeys by using a dust free bedding and forage (tied as low as possible to encourage head lowering) and maintaining good ventilation.
Why is haylage so good for the respiratory system?
When grass is packaged in an air tight environment, anaerobic bacteria such as lactic acid bacteria are encouraged to flourish allowing mild fermentation to occur. Not only does this utilise water soluble carbohydrates making haylage low in sugar but also results in a drop in pH which inhibits the growth of undesirable organisms such as moulds and fungus. This environment also makes it unsuitable for forage mites to survive, creating forage which is safer than hay from a respiratory aspect. Care must always be taken with haylage however, to prevent any damage to the packaging as just a small hole will allow over time aerobic bacteria to degrade the organic matter resulting in mould and fungus to develop. At Devon Haylage we take the hygiene of our haylage very seriously by scientifically testing the haylage for its levels of moulds, fungus and thermophilic actinomycetes. Due to our manufacturing process we can prevent any sub-standard product from being packaged in small bales, thus producing consistently high quality haylage throughout the year.
Although we can help to minimise the risk of developing respiratory disease by following the pointers above, some causes are unfortunately beyond our control and veterinary assistance may need to be sought. Vets may (along with advice for general good management to create a healthy respirable environment) prescribe treatments that include the use of antibiotics, bronchodilators, anti-inflammatories and antioxidants to treat clinical cases of respiratory disease.
The use of our quality Devon Haylage is just one way to provide your horse with a healthy respirable environment, in fact haylage was first used as a substitute for hay due to its dust, mould and fungal spore free properties – it was its original claim to fame!