What You Need to Know about Equine Parasites

Parasites. The word sends chills down your spine, doesn’t it?

No one likes to think about worms taking up residence inside their horse, but the fact of the matter is that they do. For many years, the goal has been to completely eradicate them in our horses, which has ultimately led to widespread dewormer resistance. Essentially, the worms have learned to adapt and many have become immune to certain chemical dewormers. It’s enough to make a horse owner want to panic.

But what if I told you that parasites aren’t necessarily the enemy? You might think I’m crazy, but hear me out–a few worms aren’t going to cause a problem for your horse. In fact, studies have shown that wild horses are also affected by parasites, but the levels rarely reach a high enough number to create serious health issues. The real enemy is abnormally high levels of parasites, which are created by confinement.

Horses in confined spaces are prone to parasite buildup simply because they are grazing or eating around manure where parasite eggs have been shed. Re-infestation occurs and if no intervention is made, the numbers will increase. Not surprisingly, a large worm burden can negatively affect your horse’s health.

Our goal should not be to completely eradicate parasites, but maintain a low level of infestation.

For a number of years, it was recommended that horse owners rotate the class of dewormer and administer every three months, and being the conscientious horse owner I am, this is what I did religiously for years. Now, researchers know this method is not only ineffective but further expanding the problem of parasite resistance. If you’re still blindly giving a chemical dewormer every few months, please stop!

As this article from Holistic Horse so wisely states:

In nature, parasites do not like to kill their hosts as it deprives them of a place to live. When horses are confined and crowded with others of the same species, the intestinal immune system is stressed and parasites can become a life-threatening problem. However, current literature is emphasizing that parasites are seldom the cause of serious clinical disease except in extreme situations. It is not necessary to maintain a zero fecal egg count.

With that said, here are some important things to know about equine parasites:

Fecal Egg Counts

The most important thing we can do is use fecal egg counts (FEC’s). These can be done to determine if a dewormer is needed–and also to tell if your deworming methods are working. You can have your vet do the counts or you can even purchase a microscope and FEC kit and learn to do them yourself. This is what I’ve been doing for the past few years. In fact, I just did FEC’s on two of my horses earlier this week and found only one small strongyle egg in one sample and just a handful in the other. Both are considered very low counts. I will do them again further into spring when the grass is completely in.

But depending on what type of eggs, larva, or worms are present, FEC’s will help you determine your plan of action since different dewormers target different types of parasites.

Pasture Management

Pasture management is a crucial part of parasite control. Eggs are shed in the manure and when horses eat near piles of manure, they will inevitably consume larva. If we rotate pastures, use multi-species grazing, or pick up manure in the pasture, however, we can make a big difference in their level of re-infestation. I’m fortunate enough to have plenty of space and three pastures to rotate my horses on, but I’ve also picked up manure in the past as well. If your pastures are overcrowded, this will be much more difficult, if not impossible to do, so it’s important to only keep the number of horses your facilities can accommodate.

Natural Parasite Control

There are several herbal and “natural” alternatives for parasite control, but most are just that: control. While there are a few herbs that are said to rid the body of parasites, some can be controversial (such as black walnut). I don’t feel qualified enough to comment on their use or efficacy. However, I do believe that many herbs support a healthy immune system and have anti-parasitic effects. In other words, they can create an environment where parasites feel less welcome.

Food Grade Diatomaceous Earth is also controversial for some,  but I have been using it on and off for over a year now and my FEC’s have stayed low. Coincidence? I don’t know, but I plan to continue using it unless I’m given a reason not to.

Garlic is also known to have anti-parasitic effects. In large amounts, it is not safe for horses, but many feed a small amount on a continual basis or at specific times (such as during the full moon cycle) and have had reported success.

I’ve also written about other forms of natural deworming, such as in this article on a study using micronized coconut and onion.

There are alternative forms of parasite control that have proven successful, and in some cases (especially in drier climates) they might be all that is needed. The key is to use FEC’s to ensure they’re working for your horses. Natural parasite control should also be used in conjunction with pasture and/or manure management.

Support a Healthy Immune System

Just as bacteria and viruses pose a significantly lower threat to animals with healthy immune systems, so do parasites. It’s much easier to start from scratch and build a healthy horse than to take an unhealthy horse and turn things around, but that’s not to say it can’t be done. Nutrition, environment, and stress all play major factors in the health of the immune system, and I wholeheartedly believe you can prevent high levels of parasites simply by supporting a healthy immune system.

Interestingly enough, if allowed to do so, the young horse’s immune system learns to naturally defend itself form parasitic invaders. This is called acquired immunity. If we’re constantly deworming young horses and striving for a zero egg count, they won’t develop acquired immunity though. Also quite interesting was an LSU study where horses were subjected to intensive deworming regimens for one year. The following year, researchers discovered those horses were more susceptible to parasitic invasion. Exposure to parasites creates natural immunity. The key is to not let the parasites get the upper hand though.

Of course, I would never advocate for anyone to stick their head in the sand, not deworm their horse, and hope for the best. But we must use common sense and stay updated on current research regarding equine parasites. Don’t let fear keep you in the old pattern of blindly deworming every few months. Use fecal egg counts and pasture management, support your horse’s immune system, and possibly employ some natural methods of parasite control, and hopefully you won’t have to rely on chemical dewormers nearly as much.

Ta-ta,

Casie

Sources and Further Reading

Parasites: A Primer

Herbal Worming Alternatives

Deworming Young Horses