ANTIBIOTICS are pharmaceutical products which kill or prevent the replication of bacteria, writes Euan Hemmersley of Paragon Equine Team.

The first antibiotics were developed in the 1920s and were found my accident by Dr Alexander Fleming. Since then a number of different types of antibiotics have been developed however in the last 30 years there has only been a few new antibiotics developed. Many of the antibiotics we use in equine practice are also used in other species and in human medicine.

Resistance to antibiotics occurs when the bacteria that are being targeted by the antibiotic are no longer susceptible to the antibiotic and can survive exposure to the antibiotic. Antibiotic resistance is a serous issue that can affect the welfare and health of the horses we are treating. Not only is this an issue in horses, antibiotic resistance has been found in all domestic species and is recognised as serious problem in human health. Certain bacteria are capable of causing infections in both humans and animals, this means antibiotic resistance in humans can have a negative effect on animal welfare and vis versa.

In equine practice we are striving to reduce our use of antibiotics. Before prescribing antibiotics to a horse we will examine the horse and decide if antibiotics are necessary. In many cases antibiotics are not need as the horse’s illness is not being caused by a bacteria. It is important to remember that antibiotics are not effective in treating viral conditions such as influenza. In other cases, such as equine strangles, the horses own immune system will normally clear in the infection and the use of antibiotics can lead to secondary complications. In cases where antibiotics are not prescribed supportive treatments such as anti-inflammatories or fluids will aid the horse in recovering from its illness.

There are several different types of antibiotics that all work in different ways and are effective against different types of bacteria in different locations within the body.

Recently the British equine veterinary association have developed guidelines for the use of antibiotics in equine practice. They have classified antibiotics into first line, reserved or “not for using in equine practice”.

When treating bacterial infections, we will always use first line antibiotics as our initially treatment. Reserved antibiotics will only be used in challenging cases where first line antibiotics are not effective, or lab tests have indicated that only a reserved antibiotic will be effective for treating the condition.

The third class of antibiotics are not used in equine practice because they are of critical importance in human medicine for the treatment of serous conditions.

Alongside reducing our use of antibiotics, it is important that when administering antibiotics, they are given at the correct dose following the correct regime.

It is recognised that underdosing antibiotics is a leading cause of resistance within bacteria as exposing bacteria to sub lethal doses of the agent will allow the bacteria to develop systems to prevent them being damaged by the antibiotics.

In summary, antibiotics are of critical importance in the treatment of conditions in all species of animals and humans. Reasonable use of antibiotics is needed to reduce the level of bacterial resistance that can have damaging effect on human and animal health.