Managing Resistant Parasites in Horses: It’s Up to Us

One horse owner challenges us to be proactive when it comes to our parasite control programs.

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Managing Resistant Parasites: It
The author discovered that his daughter's horse, Sultry, (pictured) harbors double-resistant parasites. | Photo: Courtesy Mike Norris

Raising awareness of anthelmintic (dewormer) drug resistance and how to deal with it is becoming critical, as we’re losing efficacy of our current dewormers, and no new ones are on the near horizon. Though I’m a trail-riding backyard horse owner—not a researcher or managing a barn full of competition horses—I’m perplexed by the apparent lack of interest I see surrounding this subject.

Resistance is not something that might happen in the future; it’s here now. My daughter’s recently acquired horse harbors double-resistant parasites. This means his worms are resistant against two of the three anthelmintic drug classes currently sold, and this is a disturbingly common situation. We generated solid evidence of his resistance status through simple fecal egg count (FEC) testing.

A 2015 National Animal Health Monitoring System survey revealed another unsettling statistic regarding this issue. Of 380 nationwide respondents (owners and managers of horse operations), 73% said a veterinarian had never recommended a fecal egg count, yet 66% expressed some level of concern about resistance.

What explains this dichotomy? Why aren’t clients more demanding of their vets? Practitioners recommend specific vaccinations to their clients based on their need, so why haven’t more vets led the revolution to improve this other important facet of equine health?

Veterinarians Please initiate this conversation with your clients. You might be astonished to learn that we horse owners care about this problem and are willing to pay for evidence-based professional recommendations, once we understand the consequences of continuing with the status quo.

Horse owners Realize that resistance is best dealt with by being proactive. If current practices prevail, resistance will surely bowl us over like a runaway horse. Mother Nature will not allow her parasites to be eradicated by drugs.

Boarders You are not absolved of responsibility because your horse doesn’t live at home. You own him, you pay the bills, you decide where he lives. As the “CEO” of your horse, you must ensure that stable management practices provide adequately for his needs, and that includes evidence-based parasite control. If your stable doesn’t have a parasite management plan, step out of your ­comfort zone and organize a meeting of boarders and stable management. Get the conversation going.

Stable operators Set yourself above your competition, and implement an evidence-based parasite management plan now. Horses must be tested and treated as individuals, but resistance has to be managed at the farm level. Boarders have no control over your pasture and manure management or the comings and goings of horses on your property. You must work synergistically with your boarders and veterinarian to effect a positive outcome.

By implementing best practices now, we can prolong the useful life of our current inexpensive drugs. We can save money by reducing the number of treatments our horses receive and by not blindly administering drugs that no longer work. Evidence-based parasite control might cause us to incur some slight additional cost in the first year but, after that, long-term costs are likely to go down for the herd. Given the amount of money we spend on our horses, is the cost of a parasite management program that is based on facts rather than assumption or tradition really the most important aspect? Are we too indifferent to change our ineffective ways for the good of our horses?

Ultimately, it’s up to us. We accept responsibility for our horses’ well-being when we buy or breed them. I beseech—no, I challenge—my fellow horse owners to do some soul-searching, get educated, procrastinate no longer, and tell your veterinarian that these are services you want. Here’s your starting point:­guidelines. But it’s up to you to take the first step.

This Across the Fence forum was originally published in the April 2019 issue of The Horse: Your Guide to Equine Health Care


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3 Responses

  1. OWNERS, WE HAVE THE TOOLS AND POWER TO MAKE A DIFFERENCE! If your Vet or Boarding Facility doens’t offer FECs, then get your own & share the results with them to encourage a change. I order FEC test kits online, receive the kits in the mail, fill the samples and return them USPS, then receive the emailed PDF results with a few days. Deworm if necessary and repeat in 2-3 weeks. If deworming is not necessary, I retest in 3 months.

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