The bond between a horse and rider competing together in any discipline is a result of years of dedicated training, with trust at the heart of the partnership. A rider takes on the responsibility of not only training their horses to perform at the level required of them, but also recognising illness and injury in the animal and treating them in a timely manner. Understanding and recognising fatigue is critically important, as a horse cannot tell us how it feels at any particular time and the rider must therefore be able to assess this for them and react accordingly.

 

What is fatigue and why is it important?

 Fatigue is the inability of a horse to continue to perform at the required level and it is a protective measure, where the horse’s body is trying to ensure that it slows or stops a physical effort before it harms itself. Without a rider, if the animal is no longer physically able to perform at the level required when fatigue sets in it would start to slow the intensity of exercise or stop completely before injury occurs. However, if a rider is asking the horse to maintain its pace or asking it for a jumping effort the natural urge to succumb to fatigue may be overridden. A fatigued horse is not only at greater risk of injury from falling or stumbling, it could also suffer from post-exercise complications such as colic, tying-up, laminitis or heat exhaustion.

 What are the signs of fatigue?

 A tired horse can be a danger to itself if allowed to continue when fatigued, and if it is competing in a fast-paced sport such as national hunt racing, may risk an accident that could cause serious injury to the rider and other horses. The signs of fatigue onset will vary depending on the activity being carried out but include:

 o    Slowing of pace

o    Decreased responsiveness to the aids

o    Unwillingness or inability to increase speed or change gait

o    Loss of motivation

o    Reduced coordination (e.g. stumbling/losing balance/wandering)

o    Increased frequency of brushing or over-reaching

o    Slowing of stride

o    Increased vertical motion

o    Increased frequency of lead changes in canter and gallop

o    Increased head and neck movement

o    Increased breathing effort

o    Hitting obstacles

o    Inability to perform a specific movement e.g. a jump

 

What causes a horse to become fatigued?

The harder a horse works, the more quickly it is likely to become fatigued, so a racehorse completing a sprint-distance race is likely to be fatigued in just one minute, and an endurance horse completing a 160km race may start to show signs of fatigue after 6 hours. Fatigue can occur in the horse’s brain (its central nervous system), in its peripheral nervous system or in the muscles themselves. Muscle fatigue occurs when the brain is sending the correct signals to the muscles, but they are unable to perform that function. The cause of this not fully understood but will likely involve depletion of energy stores such as muscle glycogen or an accumulation of metabolic end products (e.g. lactic acid). Correct muscle function is vital for athletic performance, both to provide locomotion and also for the airways to function properly. The speed at which fatigue will be present will also depend upon the age, fitness, health and athletic ability of the horse in relation to the task being asked of it and the terrain it is working across.

The role of the respiratory system in fatigue

If a horse is unable to get an adequate supply of oxygen during exercise, then its muscles will begin to produce lactic acid. Horses with very low-grade respiratory disease were exercised on treadmills for a study which found that they produced lactic acid earlier than healthy horses and therefore began to fatigue earlier. An unfit horse can be trained to improve its cardiovascular fitness and improve performance, but if a horse is healthy in every other way then the respiratory system will be the area to focus on to combat the onset of fatigue.

Even a minor loss of upper or lower respiratory function can have a large impact on the horse’s athletic performance and the early or late onset of fatigue. Upper respiratory issues such as roaring or gurgling should be immediately obvious to the rider and can often be addressed by veterinary intervention, but lower respiratory disease and an inflammation of the airways may have no outward symptoms, other than reduced athletic performance.

Ensuring a healthy respiratory system in the performance horse

Inflamed airways in the horse are often caused by them breathing in pollen, bacteria and spores that are present in hay, haylage or bedding. Forage is the worst offender, as the horse is actively placing its nostrils into the area where airborne microbes and dust will be present for hours on end as it trickle feeds. Choosing the best quality forage is important for a performance horse as is managing other environmental sources of dust and allergens, for example allowing a flow of fresh air through the stable and choosing dust-free bedding. Haygain’s range of Hay Steamers are scientifically proven to reduce respirable dust in hay as well as killing spores and bacteria, providing highly palatable and nutritious forage with a greatly reduced risk of allergic reaction and airway inflammation in horses fed it. Horses fed with Haygain steamed hay and trained to be at the peak of their physical ability have the best possible chance of competing safely without the onset of fatigue.

For more information or advice, please visit www.haygain.com or call 03332005233.

With thanks to Dr David Marlin for his expertise and contribution.