DISINFECTION is the removal or destruction of bacteria, viruses and other micro-organisms from objects or surfaces. This is usually achieved by the use of a chemical agent and is needed to prevent the occurrence and spread of disease. The range of activity of disinfectants extends from total sterility at one end to a reduction in the number of contaminating microorganisms at the other end.

Chemical disinfection is necessary because other means of sterilisation are unsuitable. Incineration and autoclaving (steam under pressure) are the best forms of sterilisation, but, as can be imagined, are totally impractical for large spaces, surfaces and equipment. High temperatures and moisture can damage electronic instruments, surfaces and objects.

Although there are many disinfectants on the market, it is nevertheless worthwhile to consider some of the characteristics a good disinfectant should have. A good disinfectant should be active against a broad spectrum of bacteria, viruses and fungi. Disinfectants should have as low a toxicity as possible, non-irritant, odourless or have a pleasant odour. They should have a high activity at low concentrations especially in the presence of organic matter (e.g., soil or faecal material).

Effects on metals, wood, plastic or paints should be minimal. It is important for a disinfectant to have a low surface tension, allowing them to penetrate into cracks and crevices. A good disinfectant should retain its potency after long-term storage. Finally, the disinfectant of choice should be relatively inexpensive.

When disinfecting objects, surfaces or spaces, the right disinfectant should be selected and the amount of organic matter reduced to a minimum. The disinfectant should be used at the concentration recommended by the manufacturer. Making it more concentrated does not necessarily make it more potent. A sufficient duration of contact time should be allowed for the disinfectant to act, as some microorganisms vary widely in their susceptibility to disinfection (e.g., bacterial spores require additional exposure time).

It is also of great importance to make up the disinfectant in clean water, otherwise it defeats the purpose. A check should also be made to see if the disinfectant of choice is inactivated by plastics.

Recent outbreaks of various diseases have emphasised the importance of a good disinfection regime. A list of approved disinfectants can be obtained from the Department of Agriculture.


When we talk about bacteria and viruses, we should also mention fungi. Fungi and their by-products (mycotoxins) have an adverse effect on the health and welfare of horses. Ringworm is another important infection that has to be controlled. It can be spread by sharing of grooming tools, saddles and harnesses.

As well as treating the affected animal, the stable and utensils must be disinfected, as ringworm spores can survive for long periods on surfaces. Stable management and hygiene is a very important element in animal care. It is better to prevent disease than waiting for it to occur and disinfection is an important part of this. When disinfecting, it is important to disinfect feed pots and water troughs in addition to floors and walls.

Tack, buckets, feed containers and equipment should also be disinfected. In outbreaks of infection the addition of a disinfectant both inside and outside stables can be of benefit. Stables should be disinfected regularly and this should form part of a biosecurity system. How often stables are disinfected depends on a number of factors, namely, the movement of different animals coming and going, and the type of stable. These factors can all have an influence. Wooden stables, especially if old, need regular disinfection. Racing yards tend to disinfect on a monthly basis.

The advent of fogging machines has helped in the disinfection process of stables. This process works by filling the stable with a fine mist which includes disinfectant. These particles are very small and remain in the air long enough to kill any airborne bacteria or virus. The benefit of a fogging machine is that even on surfaces that are never touched by other forms of disinfection, the disinfectant continues to kill any surface contamination.