When the traditional methods of deworming were designed in the 1960s, experts suggested that horse owners deworm their horses every two months. This aggressive approach to managing worms in horses was created mostly in an attempt to target the parasite known as Strongylus Vulgaris, otherwise known as the large strongyle. Over the years, this deworming approach proved to be relatively successful in the eradication of S. Vulgaris and resulted in a considerably lower amount of parasite-related deaths, but the large quantities of deworming medication that horses began to regularly receive has allowed a tolerance to build up in most horses. To put it simply; while the traditional deworming approach had good intentions and solved one problem, it eventually caused another problem.
A New Era Of Parasites
While large strongyles are now a rare and virtually non-existent parasite thanks to traditional deworming methods, there is now a new, more complex parasite known as the small strongyle that has proven itself to be quite difficult to manage.
Unlike large strongyles, small strongyles are not known to cause illness, even in horses that are not regularly dewormed. It has been discovered that the real problem when small strongyles are concerned is their larvae; small strongyle larvae reside in the body inside of cysts. When they emerge from their cyst, the horse can experience gastrointestinal pain, diarrhea, and in some cases, extreme weight loss. Traditional deworming does not seem to affect small strongyles in the larvae state, which makes it quite difficult for horse owners to help their horses manage these parasites. It has been observed that aggressive methods of parasite treatment kill off the adult small strongyle, but have little to no effect on the stage of parasite that truly causes issues within the horse’s body. Not only does this make the effort pointless; it also builds up a tolerance in the horse’s body against the medication. Over time, the tolerance prevents the medication affecting any stage of growth of parasites in the horse’s body. This means that eventually, administering deworming medication may not even rid the horse’s body of the adult small strongyle, which would make it virtually impossible to manage the horse’s parasite count.
Fecal Egg Count Reduction Tests (FECRT)
Thankfully, as the years went on after the introduction of the first deworming methods, there have been significant improvements in the way that we deworm our horses. Rather than blindly administering dewormers every couple months whether the horse needs it or not, many horse owners now have the option to have fecal tests conducted in order to determine if their horse has any parasites. If the horse’s test comes up as positive, they then receive the deworming medication. If their test returns negative, they do not receive the medication, and they will be tested again at the next interval to ensure that they have remained parasite-free.
It undoubtedly makes more sense to only administer medication to horses that actually have parasites, and this method of deworming is a large step in the right direction when it comes to the prevention of the horses building up a tolerance to the medication over time. This can be compared to the use of penicillin and other antibiotics in the human body; over time, after the introduction of penicillin and other antibiotics, doctors and medical professionals discovered that the more antibiotics the human body receives, the more of a tolerance the body builds up. This eventually renders the antibiotics virtually useless in the case of an emergency.
Ensuring that you are conducting a fecal test on your horses before choosing to administer deworming medication can make a world of difference in your horse’s parasite management. It is important that we keep in mind that once our horses build up a complete tolerance against modern parasites, we may find ourselves helpless until a new strain of deworming treatment is developed. Even in the case that this occurs, there is no way to ensure that the new treatment would definitely work, especially if the horses have built up a complete tolerance.
Horses naturally eat where they produce waste. In the wild, horses are not confined to one space, and the presence of worms may not pose much of a threat, as they do not have to graze in regions in which there are a considerable amount of waste that may contain parasites. In domestication, horses return to the same plot of land time after time to eat and pass waste, and over time, this can produce issues with parasites. In this scenario, parasites have the ability to thrive in the lush grass and manure piles, and horses that do not carry parasites have the potential to pick them up, simply from grazing from the grass.
If possible, rotate the use of pastures and paddocks. Ensure that all paddocks and pastures are completely picked out and free of manure each day, and at the change of the seasons, plow the heavily-used pastures to turn the soil. Turning the soil is an excellent way to ensure that parasites that have managed to thrive in the rich grass and soil do not have a chance of survival.
The Preventative Era
Since the introduction of traditional deworming methods in the 1960s, we have been successful in the eradication of dangerous and harmful equine parasites. We are now exiting the “deworming” era and entering the “preventative” era, meaning that it is now our responsibility to ensure that we properly manage the way we choose to administer deworming treatments to our horses. While the traditional methods of deworming may not have been ideal, experts believe that we may have caught the issue just in time before any irreversible damage occured. It is now up to us to make proactive and responsible decisions in the management of our horse’s deworming treatment.
Going forward with the information you have learned in this article, you will be able to put together a rational and responsible deworming strategy to keep your horse happy and healthy.