According to the UK’s outgoing Chief Medical Officer, Dame Sally Davies, the threat of antimicrobial resistance is as great as that of climate change, and should be given as much attention. At a time when there are very few new antibiotics being produced, antimicrobial resistance has become a global human health emergency, and this is rightly bringing antimicrobial use in animals under increasing scrutiny. Although the greatest direct threat is likely to come from food-producing animals, all sectors of the veterinary profession are affected, and there is evidence that the levels of antimicrobial resistance are actually greater in equine and companion animals than in food animal species. This may be partly because of a wider range of antimicrobials used in animals not intended for human consumption, and regulation is more restrictive for drug administration to food animals.
In addition, antimicrobials are more readily available for use “off-label” in companion animals and horses. The economic factors that affect antimicrobial use in food animals are often less important in companion animals and horses, due to their high value and importance to animal owners, so antimicrobial drugs that are important in human medicine are commonly used despite their higher cost.
All antimicrobial use can select for antimicrobial resistance, but exposure to sub-therapeutic levels of antibiotics may increase the rate of development of resistance, particularly when exposure is prolonged or recurrent. Under-dosing of antimicrobial agents appears to be common in horses; use of dose rates lower than those that result in plasma concentrations of the drug above the required minimum inhibitory concentrations may predispose to the emergence of antimicrobial resistance. Several of the doses recommended on the data sheets for antimicrobials, including procaine penicillin, fall below those now considered appropriate. Many antimicrobials used commonly in equine practice have current dosing recommendations higher than in the past, based on advances in knowledge of drug pharmacokinetics, pharmacodynamics and target plasma antimicrobial concentrations. Veterinary surgeons treating horses should be aware of the current recommended dose rates and inter-dosing intervals to ensure efficacy in therapy and to preserve the usefulness of these antimicrobials for the future. Recommendations for appropriate antimicrobial selection and dosages in horses are available in BEVA’s award winning Protect Me antibiotic use tool kit, which is regularly updated.
Whilst antimicrobials remain essential for the health and welfare of horses affected by bacterial infections, it is imperative for vets to protect their usage to maintain their effectiveness for the future. BEVA has organised a new survey to find out more about current antimicrobial use and antimicrobial resistance in equine veterinary practice. Launched at BEVA Congress, the survey will be open until the beginning of November and is directed at all veterinary surgeon members. Participants have the chance to enter a free prize draw to win £500 of BEVA CPD vouchers. The survey has been designed by Amie Wilson and Gina Pinchbeck from the University of Liverpool and is based on a similar survey conducted in 2009. The intention is to help fill in gaps in knowledge about how antimicrobials are being used in equine practice and also the current landscape of resistant infections encountered in equine practice. It is hoped that the results from the UK survey will be announced to coincide with European Antibiotic Awareness Day on 18 November 2019. In addition, we are also looking at the possibilities of running the same survey through other national equine veterinary associations in the hope that we can accumulate comparable data from other countries.