Winter respiratory health

The colder months can challenge a horse’s airway function, at work and rest. Richard Hepburn FRCVS offers solutions for the season ahead

Improving a horse’s airways in the colder months

WINTER is the perfect time to reassess your horse’s stable management, with the aim of improving the quality of his breathing zone.

We saw in part one of this series (15 October) how creating a cleaner indoor living environment, with fewer airborne particles, will reduce the likelihood of airway inflammation and the subsequent development of equine asthma (EA). Yet both turnout and exercise can create additional breathing challenges…

Arena exercise

THE concentration of respirable particles in an indoor arena is dependent upon its setting and construction, both the type and humidity of its surface and the number of horses being trained at the same time.

Working a horse on a surface liberates particles, which are then dispersed into the school environment. An increased number of horses using the school will worsen this, with trotting and galloping producing the greatest quantity of respirable particles.

While the effect of different surface types is unclear, the release of particles from damp surfaces is less than that from the same surface when dry. This may be related to surface penetration: when the material is dry, a horse’s feet will sink more deeply and disperse a greater amount of material.

Further factors will affect arena air quality. If connecting doors to stables are left open during mucking out or forage feeding, this will increase respirable particle levels. Improvements will occur, however, after cleaning the arena border and solid surfaces including seating and obstacles, to remove dust and contamination.

Ventilation from the outside, away from other sources of dust such as stables, access roads, parking areas and muck heaps, will also help.

Key message: close connecting doors to stables but open any windows that will let clean air in, and keep the school surface well-dampened and its surroundings dust-free. A horse with EA should be exercised alone indoors, ideally before others or after a period of ventilation.

Outdoor work

STRENUOUS exercise in cold air has been shown to produce prolonged suppression of local immunity within the lungs, which researchers postulate could increase the risk of respiratory viral infection such as equine influenza. It is unknown if this reduction in immune function has any effect on allergic airway disease, so the traditional advice that a good blast in the cold will help the lungs is unproven.

Exercising in temperatures below freezing can cause bronchoconstriction, where the airway narrows due to contraction of the surrounding muscle.

This can occur any time, from immediately afterwards to several hours later, in otherwise healthy horses. We don’t yet know whether underlying environmental airway inflammation makes this more likely.

Key message: if your horse has a high breathing rate or is coughing after exercise on a cold day, consult your vet.