Antimicrobial Resistance explained

The issue of parasite resistance in relation to worming horses has been well publicised in recent years, leading to a greater understanding of the problem. However, another threat
– Antimicrobial Resistance (AMR) – is in urgent need of attention.

Norodine Granules can be effective in treating general infections in horses

Norodine Granules can be effective in treating general infections in horses

“While we’ve certainly not got parasite resistance under control yet, worming is something owners do regularly with their horses, which means it’s become better publicised and understood,” says Dr Kirstie Pickles, a European specialist in equine internal medicine at Scarsdale Vets (part of the XLEquine group) in Derby.

“On the other hand, most horse owners won’t often have to give their horses antibiotics. It’s far more unusual and the issues surrounding AMR are therefore less well understood, despite the related risk factors being much greater.”

What is AMR?
AMR refers to resistance developed by bacteria to antibiotics – something that’s recently been classified as a disease in its own right. It’s now a clinical problem on an international scale and one of the largest threats to equine and human health.

So why is it only being flagged up with such urgency now? As Kirstie explains, antibiotics have been used for a long time, however they’ve been used extensively and not always appropriately. “If people are given five days’ worth of antibiotics for their horse, they’ll often only use three days’ worth, until the clinical signs of an infection have gone, then save the remaining antibiotics to give to their horse at a later date, without the guidance of a vet.” Not finishing a full course of antibiotics means not all offending bacteria will be killed, increasing the likelihood of resistance developing. But it’s not always our fault. Under-dosing can also be the result of horses refusing to eat feed containing the antibiotics they need. Kirstie’s advice? Mix antibiotics with water to create a paste, which can then be administered to your horse via syringe, much like when worming.

Time for action
To tackle the problem of resistance, the British Equine Veterinary Association (BEVA) has advised vets to self-regulate, only giving antibiotics when cases absolutely require them and being more selective about the types of antibiotic they use. “Particular antibiotics used in human medicine are the same as those used in animal medicine,” says Kirstie. “New antibiotics are only licensed infrequently, which means we have to be strict on our use of the antibiotics we have. Added to this, very few are licensed for use in horses,” says Kirstie. “In fact, there’s only one antibiotic licensed for oral use in horses. Others can be injected, but this is much harder for owners to do themselves.”

What can you do?
Aside from always following the advice of your vet, only ever give antibiotics when they’ve been prescribed, and do your best to ensure your horse gets the dosage he needs.

Ultimately, prevention is the best chance we have of slowing down resistance. “Prevention is always better than treatment,” says Kirstie. “This means better biosecurity to prevent infections in the first place.” 

Imogen Johns, Senior Lecturer in Equine Medicine at the Royal Veterinary College, says it’s time we took responsibility: “Resistance to antimicrobials, including bacteria that are resistant to all commonly used antibiotics, does appear to be an increasing problem in horses. These resistant bacteria can be part of the normal bacterial population of the horse, such as on their skin or the intestinal tract, but they can also cause infections, which become very difficult to treat. At present, the best way we know of minimising the development of resistance is to use antibiotics responsibly – that is, only use them when there is a true bacterial infection (not a virus!), and reserving so-called ‘powerful’ antibiotics only for severe and life-threatening infections.”