Life at times is rather complex - and requires us all to adapt. Adaptability is a valuable trait in evolution that has been endowed by nature to many of the organisms present on earth.

Most of us are aware of the growing problem of the resistance of various forms of bacteria to certain antibiotics. Doctors now are administering counteractive medications when the situation deems it necessary. You should not be surprised when these medications are targeted against parasites. As they, too, have adapted well to the medication-drenched environment that surviving is not a problem for them. And for horse owners, this could be a major problem.

What Happens in Drug Resistance

In the different equine parasite species, there will be one that develops genes that makes them invulnerable to certain deworming agents more than other kinds. Once they survive a deworming routine, they will move on to the next phase – breeding. They will be lucky enough to pass down their “advantageous” gene. The sad fact is that the parasites with the gene advantage tend to increase while those that do not develop resistance tend to diminish in numbers.

The results then become obvious - the so-called equine dewormers that we use become less and less effective. This is due to the increased survival rate of the worms from resistance. It is always advised that using a different class of deworming agent helps to increase success rate of killing the parasites.

Be Careful with Your Favorite Deworming Agent

Because you have discovered that a compound like Ivermectin has been so effective in eliminating unwanted worms, you may decide to stick to it. While it may be tempting to do so – don’t. This can develop into a problem of parasite resistance. These resistance problems are not innate – they develop. Which means that these parasites mutate over time in a specific population. These mutations can be beneficial to the organism (because it allows them to become resistant to medications). However it can be a serious health threat for the host.

Dewormer resistance is now a global problem. The patterns could differ from one country, region, or farm to another.

The Value of Fecal Egg Count Test

Parasite resistance is a serious problem for many horse owners. Fortunately, fecal egg count tests can be performed to identify if your farm has been affected by the problem. This test measures the parasite egg count in your horse before and after administering the deworming agent to see if the particular agent is effective in treating parasite infestation.

It is important to understand that fecal egg count testing should be performed before you think about giving your horse any deworming medications in order to have a basis of information that you can compare with.

For instance, you are using a benzimidazole (fenbendazole) class of wormers and you will expect that there will be a 90% reduction rate in the egg count. If the results show that the rate is lower than that, there is a possibility that resistance has inflicted your farm – at least to that specific class of wormer.

The fecal egg count test is an important tool to assess how great or less of a problem resistance is to your specific location. Keep in mind that it’s best to ask your local veterinarian for help when it comes to doing this particular test and getting advice based on the results.

Parasite resistance is a serious problem for many horse owners.
Parasite resistance is a serious problem for many horse owners.

What Can You Do?

Fighting worm resistance must start with choosing the right type of wormer for your horse. In this case, it also helps to know about the different parasites that take refuge inside your horse’s stomach by allowing your veterinarian to test your horse. Knowing the culprit will definitely help you find the best weapon to attack .

Do not overdo deworming. Give deworming agents only when necessary. Parasites have long been a part of this planet and we can’t simply do anything about their extinction. They develop certain characteristics that allow them to survive. They are also part of the circle of life – they need a host in order to survive. But that doesn’t mean that we should just let parasitism be. It also does not mean that we compromise safety and health of the horse just so these parasites don’t stand a chance in surviving. Being infected by parasites in a minimal way is acceptable but when the infection is overwhelming, with very obvious unhealthy signs, then deworming agents will come to the rescue. It is important to understand that no matter how hard you could try, eliminating parasites to zero is impossible.

You also need to aid the help of your veterinarian in confirming resistance in your specific location and ask which active ingredient will be best used.

Giving the right dose of worming agent to the horse according to its weight also helps lessen resistance problem. Most importantly, you can’t just rely on deworming agents to do the job of killing off those parasites. It is also your responsibility to make sure that the horses environment is clean and free from fresh manure. Clean water is essential.