If in doubt, don’t! The dangers around antibiotic resistance in horses *H&H Plus*

  • Antibiotics should only be used when there is no alternative, or we will be powerless to fight infection in the future, warns David Rendle MRCVS

    Antibiotics – more correctly termed antimicrobials – have revolutionised the way we treat infectious disease, thanks to their ability to slow down or destroy the growth of bacteria.

    However, no one can escape the increasing discussion in the media around resistant bacteria and concerns that antimicrobials are no longer working.

    For decades, there has been a tendency to use antimicrobials “just in case” there might be infection, or because infection could develop. The emphasis is now on using antimicrobials only when there is no alternative.

    In a number of European countries, antimicrobial use in animals has been restricted to ensure the most important treatments are reserved for humans. Farmers have reduced antimicrobial use dramatically and the equine industry is now under pressure to do the same.

    If we cannot demonstrate an ability to decrease our dependence on these medications, there is the possibility that the UK Government could step in to prohibit the use of certain antimicrobials in horses.

    Taking action

    Every horse owner has a responsibility to support their vet and to work with them to balance their horse’s immediate requirements with the need to preserve the effectiveness of antimicrobials. We’ve compiled 10 essential tips to consider…

    1. Trust his immune system.

    Antimicrobials are only necessary if your horse’s immune system cannot cope. Not every infection needs antimicrobials: minor wounds will heal, and foot abscesses will clear up if they can drain.

    2. Don’t kill the good guys.

    Your horse needs bacteria, so don’t destroy them unless you have to. Not only does he digest his food courtesy of billions of bacteria in his large intestine, but bacteria on his skin and in his respiratory tract provide essential protection against others.
    Antimicrobials kill bacteria indiscriminately and can cause diarrhoea or other infections by removing the “friendly” bacteria.

    3. Understand the issues.

    Vets often feel under pressure to prescribe antimicrobials. Let your vet know you are aware of the issues and that you don’t want them used unless they are absolutely necessary. If your horse does require antimicrobials, check with your vet which class they propose to use. Work with them to avoid the use of highest-priority critically important antimicrobials (HP-CIAs), which are essential in human medicine and should not be used in animals unless there is absolutely no alternative.

    Liquid antimicrobials issued in bottles will be either enrofloxacin or doxycycline hyclate. While these liquid preparations may be easier to administer to horses, there are more appropriate alternatives for both and these should be avoided where possible.
    4 Pinpoint the problem.

    Get a proper diagnosis, rather than using antimicrobials because your horse might have a bacterial infection. A cough is more likely to be an allergy, for example, while a temperature may well mean a virus – neither of which will benefit from antimicrobials.

    5. Invest in tests.

    Without testing, your vet must make an informed guess as to which antimicrobial is the most likely to be effective – and won’t always be right. Ask if any tests are available to guide selection. Culture and sensitivity testing can be used to grow the bacteria in a laboratory and to identify the most effective antimicrobials.

    Your vet may not initially discuss testing because of the additional cost. Think of it as money well spent; testing is less expensive than the antimicrobials, and ensures that funds are not wasted on ineffective treatment.

    6. Help the medicine down.

    Under-dosing increases the risk of resistant bacteria developing. If your horse is not finishing the food that contains the treatment, or if some of the liquid that should go into his mouth ends up on the floor, ask your vet for an alternative. There are antimicrobials specially formulated for horses, which are much easier and safer to give.

    7. See the bigger picture.

    Ask yourself whether you are acting responsibly by keeping antimicrobials and using them without veterinary guidance. There is still a concern that many yards stockpile antimicrobials, and it has been suggested that some use them in the mistaken belief that they might improve performance, rather than to treat life-threatening disease.

    This has major implications. Locally, you are increasing the risk of resistant infections developing on your yard and affecting the horses and people within in it. Globally, you are hastening the development of antimicrobial resistance – which already kills 12,000 people in the UK annually.

    8. Guard against infection.

    Take measures to prevent bacterial infection developing. Vaccinate against respiratory viruses such as influenza and herpes to reduce the risk of bacterial pneumonia, and maintain regular dental checks to help prevent dental infection.

    At the yard, good housing and air hygiene will lessen the likelihood of equine asthma and secondary respiratory infection. Keep stables, gates and fencing in good repair to prevent unnecessary injuries, and try to avoid turning horses out in overly wet, muddy conditions for long periods, to keep mud fever at bay.

    9. Administer with care.

    Follow the instructions with any antimicrobials. Dose your horse with the correct amount, as advised by your vet, and always complete the course. If this isn’t possible, speak to your vet and discuss an alternative, and dispose of any unused antimicrobials responsibly. Store medicines in the fridge, where instructed, and otherwise in a cool, dry place.

    10. Practise biosecurity.

    If a horse does develop an infection, take adequate biosecurity measures to prevent the spread of bacteria. Wear gloves, wash your hands after treating the horse, dip your boots in a disinfectant bath and dispose of infected dressings appropriately. Resistant bacteria present a threat to you and your staff, as well as to all horses at the yard.

    Understanding bone fractures

    Antimicrobial resistance presents a huge human health issue that scientists predict will soon overtake cancer as a cause of death. By 2050, it is estimated that every year 10 million people worldwide will lose their lives as a result of bacterial infections that can no longer be treated. Healthy people already die when minor injuries or surgical incisions become infected with untreatable bacteria. Virtually all of the multi-resistant bacteria that worry doctors have been identified in our domestic animals. Equine hospitals mirror the situation in human hospitals, with potentially fatal complications associated with resistant bacteria becoming more common, causing horses to be euthanased.

    It is unlikely that new antimicrobial classes will be made available for horses, so we have to use the current options more responsibly and sparingly. Other means of preventing and controlling infection, such as medical grade honey or medicinal maggots, are becoming increasingly important.

    Ref: 14 January 2021

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