Looking after your horse for optimum performance

If a horse can`t breathe, it can`t work. Anything that affects the lower airway has a tremendous impact on a horse`s performance. Respiratory disease is second only to musculoskeletal disease in being the most commonly diagnosed cause of poor performance, exercise intolerance, interruption of training and premature retirement in racehorses and eventers. There is also a direct link with increased costs of vet bills and preventative measures.

Respiratory disease manifests in a variety of guises but typical is the racehorse not finishing his race or an eventer getting time faults in the cross-country phase. Over the last few years there has been a marked increase in research into how respiratory disease impacts on a horse`s ability to achieve its peak performance.

The terminology that describes respiratory tract disease is complex, but two conditions exist that commonly affect stabled racehorses, especially at young ages and event horses, especially those who are seven and older at the height of their competitive lives.

Inflammatory airway disease (IAD) has subtle clinical signs such as poor performance, exercise intolerance, coughing and excess respiratory mucus. Horses with IAD do not display any obvious increased respiratory effort.

The second is a serious condition affecting the performance of the racehorse and the eventer and often signalling the end to a horse`s athletic career. Chronic obstructive pulmonary disease (COPD) is characterised by exercise intolerance, coughing, increased nasal mucus secretions and increased breathing effort such as flared nostrils and `abdominal` breathing (often described as `heave lines` along the horse`s abdomen - hence the alternative name of `heaves` for the condition).

Both conditions are caused by damaging aerosols (tiny airborne particles) in the horse`s daily environment. The growth of moulds in hay and straw (the main culprits are Aspergillus fumigatus, Faenia rectivirgula and Thermoactinomyces vulgaris) are particularly damaging to a horse`s breathing. The horse inhales these fungal spores on a regular basis which triggers the airways to become hypersensitive. A type of allergic reaction follows. Cells that line the airways respond by trying to engulf the particles and other cells increase their production of mucus. This inflammatory response causes the airway walls to thicken and constrict causing widespread airway obstruction in the deep lung areas, forcing the horse to increase his breathing efforts in order to move air in and out of the lungs. It is like trying to squeeze the air out of an inflated rubber balloon that is pinched at the neck. A horse with long-term COPD has had to endure extreme efforts to aerate his lungs and this results in the heave line along his abdomen as the breathing muscles have enlarged over time.

An obvious result of COPD and to a lesser extent IAD, is the horse has to make extra breathing effort to get enough oxygen into his system to convert to energy in the cells. This is thought to be one of the reasons behind the exercise intolerance characteristics of the disease and the reduced performance levels in affected horses.

In one UK study of racehorses in a single training yard 724 tracheal aspiration samples were taken from animals aged two to ten years old, all in full training. 18.8% of the sample were classified as suffering from IAD. In a study of racehorses in Australia, horses with no history of respiratory disease entering a racing yard for the first time had samples taken and then again after two and four weeks. Of the 165 horses evaluated, 41% developed IAD in the two to four week period after having entered the yard.

Considering your horse`s environment is very important to his short- and long-term wellbeing. Prevention of respiratory disease should focus on decreasing the levels of airborne particles and irritants in the horse`s daily surroundings.

Stables should be well ventilated (but not draughty). Bedding should be relatively dust- and spore-free, for example paper. Hay should be steamed to kill fungal spores and dampen down dust (soaking hay does not kill spores). Stabled horses should be turned out daily.

The most successful yards maintain very high management standards which are reflected in their horses` performances, be it in eventing or racing. Racehorses from these top yards regularly feature in free racing tips, both online and in the racing press.