Written by Rosie Hutchins BSc (Hons).
It is currently common practice for horses to be contained in a confined space for prolonged periods of time, whether it is while they are stabled or being travelled. There has been lots of published research looking into the dust environment surrounding horses while they are stabled, however nothing so far has looked at the impact of dust during travelling.
This study examined the dust environment while travelling a horse in a lorry and if different treatments of the forage could affect this. The chosen forage was hay and the three treatments included dry, soaked and steamed. This was a continuation of research done looking into the treatment of hay and the effect it has on the breathing zone of stabled horses. The current research and understanding is that the surrounding respirable dust environment during periods of being stabled can be very changeable and have a major effect on the horses health.
Horses are highly sensitive to dust and mould particles therefore excessive inhalation of these could lead to breathing problems, both short and long term. This has been shown to be the case in stables but it is yet to be seen if these factors have the same effect while travelling (Curtis 1996, Waran 2002, Moore-Colyer 2015, Clements 2006, McGorum 1998, Woods 1993, Jones 1989 and Niedzw 2014).
Taking information from various comparable studies helped with making predictions for possible outcomes. It had been found that the airborne dust concentrations were significantly greater around a horses breathing zone compared to the general stable environment. This is significant as when horses are travelled haynets are often placed very close to their muzzle. While a horse is eating forage, ventilation makes only a very small impact therefore changing the treatment to the forage will have the biggest impact on the dust environment.
Performance horses exert a large amount of energy for their chosen discipline and the respiratory system is of great importance to being able to compete to the best of their athletic ability. Respiratory conditions such as recurrent airway obstruction (RAO) can be very damaging to a horses performance career, with the respiratory system proving to be the most limiting factor in a race horse. This therefore makes any improvement to a horses dust environment whether it being while stabled, or travelled or both very important to ensure as high a quality of performance as possible. This even applies to recreational horses that should remain in the best health possible.
The set up of the experiment was for three haynets to be prepared and each to be weighted at 5kg (<50g>) before treatment to ensure all had the same dry weight. All haynets were tied to the same place in the lorry, along with the air sampler in the horses breathing zone (See picture). For soaking the hay a time of 30 minutes was decided from previous experiments. Steaming the hay was done in a HG2000 for a period of 50 minutes to ensure temperature reached over 80°C.
The horse was then travelled for 30 minutes with each haynet before it was swapped for another which had undergone a different treatment. This time of 30 minutes had been determined by a pilot study which had been undertaken to determine the most appropriate time for a suitable amount of dust to be collected. Once the data had been collected the filter papers where taken to the labs and studied under the microscope so the dust particles could be counted.
The expected results following on from previous research would be that the steamed hay would produce the least amount of dust particles and the dry hay the most. This is from previous research conducted looking at treating hay while stabling horses. Alongside looking into whether forage affected the respirable dust environment, the experiment also used four different horses to determine if individual behaviour had an effect. The results were not statistically significant for this factor. While this is often a factor in stabled horses due to the limited space in a lorry it has less of an impact.
The results then showed there to be statistical significance (P<0.001) for the treatment of forage making a difference to the dust environment in the breathing zone. Dry hay produced the highest amount of dust particles, followed by soaked hay and finally steamed hay producing the least amount. Steaming is becoming a much more popular way to treat hay and in this experiment it was shown that soaking hay produced twice as many dust particles in comparison to steaming.
It has also been shown in a previous study that steaming hay not only improved the dust environment in the immediate breathing zone of stabled horses but also in the general stable environment. This could make it even more appropriate for travelling horses, especially for multiple horses, due to the confined space any improvement to the general environment would greatly benefit the horses health. Steaming is therefore shown to be the most effective treatment for reducing respirable particles when travelling a horse.
Curtis, L., Raymond, S. and Clark, A. (1996) Dust and ammonia in horse stalls with different ventilation rates and bedding. Aerobiology
Jones, W. E. (1989) Equine Sports Medicine. Lea and Fibiger
McGorum, B. C., Ellison, J. and Cullen, R. T. (1998) Total and respirable airborne dust endotoxin concentration in three equine management systems. Equine Veterinary Journal. 30: 430-434
Moore-Colyer, M. J. S., Taylor, J. L. E. and James, R. (2015) The effect of steaming and soaking on the respirable particle, bacteria, mould and nutrient content in hay for horses. Journal of Equine Veterinary Science. 39: 62-68
Niedzwiedz, A. (2014) Equine recurrent airway obstruction. Mac Vet Rev 37 (2): 115-120
Waran, N. (2002) The welfare of horses. Vol. 1. Kluwer Academic Publishers
Woods, P., Robinson, N., Swanson, M., Reed, C., Broadstone, R. and Derksen, F. (1993) Airborne dust and aeroallergen concentration in a horse stable under two different management systems. Equine Veterinary Journal. 25(3): 208-213