Prevalent Parasites: Common Types of Equine Internal Parasites

Many horse owners know that deworming is important but they may not be aware of all the specific types of parasites that dewormers also known as anthelmintics treat. Deworming along with other management practices helps to keep a horses internal parasite load at an acceptable level. Internal parasites are small organisms that live out part of their life cycle within the horses body with the potential to cause illness. They inhabit specific tissues organs and systems of the horse deriving nutrients from the horse so they can continue to grow and develop. While there are many species of internal parasites that infect horses some of the most common are strongyles ascarids tapeworms pinworms bots and threadworms.

This article will describe how parasites infect horses why we are concerned about internal parasites and the basic life cycles and symptoms of 6 common equine parasites.
How do horses get infected with internal parasites?
To start with a parasite is defined as an organism that lives on or in a host in this situation the horse is a host. The life cycle of a parasite includes stages within the horse and stages outside the horse. The stage of life when the parasite can infect the horse is referred to as the infective state. Eggs andor larvae are found in the horses environment most commonly pastures. While grazing the horse accidentally ingests the parasitic larvae or eggs. Once consumed the parasite will migrate to the desired area of the body where it matures into an adult and reproduces.
They can cause damage while migrating through and feeding on these organs. A lot of parasites find this new home within the horses digestive tract but some migrate to other tissues and organs. For example ascarids roundworms migrate from the gut to the heart liver and lungs and then back

to the gut. How long a parasite resides inside the horse varies by the type of internal parasite. Some parasites such as ascarids will stay in the body for weeks while others such as small strongyles can remain in the gut for over two years.
Why are we concerned about internal parasites?
Heavy internal parasite loads can cause undesirable effects on your horses health.  Externally you may notice weight loss poor growth coarse and dull coats potbellies andor excessive tail scratching. Various types of colic can also occur from internal parasite infestations. In young horses infected with ascarids diarrhea is also a