Alan Creighton, BSc (Hons), Head of Environment and Nutrition at the Irish Equine Centre
The main part of our work within the Environment and Nutrition department at the Irish Equine Centre (IEC) is working with racing yards, sport horse performance yards and stud farms where we investigate cases of poor performance and respiratory disease outbreaks, design biosecurity systems, as well as mainstream commercial testing of soil, pasture, water, feed and fodder. Our clients are here in Ireland, as well as the UK, France, Japan, the USA and UAE.
We improve the consistency of equine performance by implementing best practice in terms of biosecurity, yard layout, stable design, ventilation, nutrition, and water testing, with the goal of providing security from exposure to harmful pathogens to include parasites, bacteria, viruses and fungi. When talking about biosecurity we promote a holistic approach. For example, there is no point having a good vaccination and stable hygiene programme in place while allowing the propagation of parasites on the land used for grazing; just as there is no point in following a worming programme without paying attention to stable hygiene. Poor quality hay, forage, feed and bedding can all impact on the health of any population of horses. In financial terms, good biosecurity makes good financial sense. If we can minimise disease, we can maximise the performance of any type of equine premises.
Performance horses once stressed will always get sick, but there are parameters and exposures within any equine premises that we can control, such as stocking density, isolation of new stock, air quality, water quality, stable hygiene, hygiene in indoor exercise areas, food quality and storage. The Environment and Nutrition department at the IEC has proven time and time again that by improving these factors we can lower the incidences of disease, it just takes the correct mindset and discipline.
Being proactive is always cheaper than being reactive and preventative measures can greatly reduce treatment, loss of time in development of the animals, labour costs and loss of performance in all equine disciplines.
Biosecurity:
Biosecurity can be described as “Providing security from exposure to harmful pathogens to include parasites, bacteria, viruses and fungi”.
The major disadvantage for modern stud farms and for performance horses is the need to travel to competitive events, stud farms and sales, where they are mixed with other animals which will have travelled both nationally and internationally. This is often a means of spreading infectious respiratory disease (Powell, 1985). A good vaccination programme, isolation of sick animals, isolation of new stock coming onto the farm, or animals returning from sales, helps defend against the spread of viruses and other diseases.
We can protect against bacterial challenge with good hygiene, isolation, and ensuring the quality of food and water. Fungal spores and hyphae can penetrate the lung and also trigger an immune response (Madelin et al., 1991). If animals are in continual contact with pathogenic fungi, their immune system is likely to be challenged which can often leave the animal open to secondary disease issues. The environment has a major influence on the levels of fungi. We now know that hygiene, ventilation, forage and bedding quality in a yard have a big impact on how w#e can control the exposure to fungi. These environmental factors play a key role in the development of respiratory diseases. Horses when housed indoors can be exposed to high levels of bacteria and moulds which are naturally present in their bedding and forage (Webster et al., 1987). Respiratory infections, for example recurrent airway obstruction (RAO) and exercise induced pulmonary haemorrhage (EIPH) are major causes of poor performance in all performance horses. Mild to moderate equine asthma (EA) is associated with poor performance, occasional coughing and lower airway inflammation, often resulting in excess mucus within the tracheobronchial tree and an increase in airway inflammatory cells (Couetil et al., 2016). It is recognised in all ages of horses taking part in all equine performance disciplines. The impact of respiratory disease will depend not only on the nature and severity of the disease but also on the equestrian discipline performed (Morris & Seeherman, 1991).
Fungi and mycotoxins are recognised as a major cause of these conditions (Buckley et al., 2007; Carson & Ricketts, 2010). The incidence and severity of respiratory disease are dependent on the everyday interaction between the horse and its environment. The management and housing practices not only have an influence on the horse’s susceptibility to disease but also the levels of respiratory pathogens to which it is exposed (Clarke, 1987).
When attempting to control exposure to fungi we need to be aware of how we store forage and feed, where it is stored and the importance of keeping it moisture-free. Performance horses and, in particular, racehorses need a high level of ventilation and stable hygiene. They require spotless exercise areas, walkers and indoor exercise areas, in addition to well-ventilated hygienic boxes. The most successful trainers have an unbelievable level of attention to detail in this regard.
Yard layout:
Consider how the premises is laid out. Disease will build up and spread in the areas most used by horses and areas used by all horses on the farm pose the greatest risk. Walkers, wash bays, vet boxes, transport vehicles are examples of high-risk areas. For example, it’s important that the hay barn doesn’t share the same air space as the horses stabling. Avoid shared air space between stables, feed and fodder stores, exercise areas, tack rooms, rug rooms and vet boxes or treatment rooms. By separating units and stores you are minimising the chance of disease spreading. There is no point in having a biosecurity regime in place if you then have the manure heap too close to food storage, bedding, walkers or the horses themselves. Avoid the possibility of the wind blowing spores, dust and microbes straight back into the horses’ environment.
Ventilation:
One of the main factors for controlling the environment in stabling is ventilation. The quality of air entering the stable, where and how it exits and the potential influence of the air quality in neighbouring stables within a common airspace should all be considered (Clements & Pirie, 2007b). The basic principle of ventilation is that we need cold air to replace warm air and that warm air to remove moisture, dust, ammonia, spores and microbes when exiting the building.
It is important to provide adequate ventilation without draughts at horse height (Sainsbury 1981; Clarke 1987a, b). We advocate for controllable ventilation at horse height and permanently open ventilation above the horse’s head. There must be a vent at the highest point in any building for stale air to exit (Figure 1). Sunlight is a natural disinfectant so plenty of natural light is helpful but not too much so as to make the stable too hot.
Figure 1. Correct ventilation draws warm air and contaminants up and out of the stable and cooler, fresh air into the stable. Credit: A. Creighton
Forage and bedding:
Mould spores and dust can originate from various sources, such as hay/ haylage, bedding and feed, which are substances that the stabled horse encounters on a daily basis. It is under certain conditions that moulds grow unnoticed and in turn can produce mycotoxins (see Moulds and mycotoxins in forages for horses). It is essential to limit the contact that race and performance horses have with moulds and their mycotoxins. The most common source of mould exposure for a horse is forage, and all forage will have some mould spores present. These spores can originate from field mould pre-harvest and storage mould post-harvest (Clarke & Raymond, 2001). Nelson et al. (1983) stated that storage is the most important factor that affects physical changes and deterioration in forage quality.
It is important to test fodder and bedding prior to use and to improve and monitor environmental conditions in which they are stored. Nelson et al. (1983) stated that storage is the most important factor that affects physical changes and deterioration in forage quality. Don’t ever store feed and hay in the same space as horses. Don’t store good hay near old hay, as the mould left behind will infect the new hay. Haylage should be fed within 48 hrs once opened during the summer and 72 hrs in the winter. The area where haylage is opened should be clean, uncluttered and disinfected on a regular basis. This area when not maintained becomes heavily contaminated with pathogenic moulds and becomes a vector for mould contamination of newly opened haylage. Never feed forage from the same wheel barrow that you muck out into. This practice is a great way to spread infectious agents. Feed should be fed from bags in the bin rather than loose in bins. The feed house should be a clean, hygienic tidy place.
The IEC use moulds as a marker organism for a poor-quality environment and unhygienic conditions. If there are high levels of mould present in the stable environment it will also be suitable conditions for many other diseases. Consequently, if you control the mould growth you will also control the growth of many other microbial pathogens.
Water:
Water quality can be adversely affected by high levels of Cryptosporidium (microscopic parasite spread via contaminated water), faecal bacteria, iron, aluminium and other antagonistic metals. Water quality is particularly important and influential on performance. Where horses are not thriving, with dull coats, we’ve found particularly high levels of metals or antagonistic minerals in the water.
Isolation unit:
A functioning isolation unit is essential, with no shared air space and as far from the main stabling as possible. It should have its own stock of feed so that staff are not back and forth from the main area. The isolation unit should be a distance from any other stabling and it is advisable to keep mares and foals, yearlings and barren mares separated. Isolate horses coming back from the sales and remember that people can also spread disease. Don’t allow visitors if they are coming straight from other yards, such as vets, farriers etc, unless they have a change of clothes and have washed their hands. The same thing goes for staff who might have their own horses at home. Different wheelbarrows should also be used for straw during an outbreak of enteric disease (disease due to intestinal infection). Remove used bedding from infected stables and away from the yard as soon as possible. Never store mucking out equipment in feed stores.
General hygiene:
Ensure veterinary staff thoroughly clean equipment between scopes and wear disposable gloves that are changed between horses. If the vet or farrier is attending, ensure they attend to any respiratory infected animals last.
In high performance yards it is important to keep competition or older racehorses away from youngstock. Separate walkers are preferable. Walkers are a serious vector for the spread of disease and require constant cleaning and disinfection.
Establish a disinfection routine that everyone is aware of and make it part of the maintenance routine. Every yard should be power washed a number of times a year. Preferably use disinfectants that have been approved and tested against equine specific pathogens. The frequency of disinfection will depend on ventilation, age of the buildings, dampness, bedding and feed quality.
A high level of biosecurity is achievable in all types of equine premises and makes financial sense. Good biosecurity takes a lot of planning and the involvement from everyone on the premises. A good biosecurity policy must be practical for a busy farm or yard. It is about attention to detail and control over the parameters we can control.
REFERENCES
Buckley, T., Creighton, A., & Fogarty, U. (2007). Analysis of Canadian and Irish forage, oats and commercially available equine concentrate feed for pathogenic fungi and mycotoxins, Irish Veterinary Journal, 60(4): 231-236.
Clarke, A.E. (1987). Stable environment in relation to the control of respiratory disease. In: Horse Management Ed: J. Hickman Academic Press, London pp 125-174.
Clements, J. M., & Pirie, R. S. (2007a). Respirable dust concentrations in equine stables. Part 1: validation of equipment and effect of various management systems. Research in Veterinary Science, 83(2): 256–262.
Clements, J.M., & Pirie, R.S. (2007b). Respirable dust concentrations in equine stables. Part 2: The benefits of soaking hay and optimising the environment in a neighbouring stable. Research in Veterinary Science, 83: 263-8.
Couetil, L.L, Cardwell, J.M., Gerber, V., Lavoie, J.P., Leguillette, R., & Richard, E.A. (2016). Inflammatory Airway Disease of Horses, Revised Consensus Statement. Journal of Internal Veterinary Medicine, 30: 503-15.
Madelin, T.M., Clarke, A.F., & Mair, T.S. (1991). Prevalence of serum precipitating antibodies in horses to fungal and thermophilic actinomycete antigens: effects of environmental challenge. Equine Veterinary Journal, 23(4): 247‐252. 10.1111/j.2042-3306.1991.tb03711.x.
Morris, E.A. & Seeherman, H.J. (1991). Clinical evaluation of poor performance in the racehorse: the results of 275 evaluations. Equine Veterinary Journal, 23: 169-174.
Nelson, B. D., Verma, L. R. & Montgomery, C. R. (1983) Effects of storage method on losses and quality changes in round bales of ryegrass and alfalfa hay, Louisiana State University Agricultural Center: Louisiana State University.
Powell, D.G. (1985). International movement of horses and its influence on the spread of infection. In: Society for Veterinary Epidemiology and Preventative Medicine, Proceedings, Reading 27-29 March 1985, Ed. Thrusfield, M.V., pp 90-94.
Sainsbury, D.W.B., (1981). Ventilation and environment in relation to equine respiratory disease. Equine Veterinary Journal, 13: 167-170.
Webster, A.J., Clarke, A.F., Madelin, T.M., & Wathes, C.M. (1987). Air hygiene in stables. 1: effects of stable design, ventilation and management on the concentration of respirable dust. Equine Veterinary Journal, 19(5): 448‐453. 10.1111/j.2042-3306.1987.tb02641.x.