Internal parasites are silent killers. They can cause extensive internal damage, and you may not even realize your horses are heavily infected. At the very least, parasites can lower resistance, rob the horse of valuable nutrients, and cause gastrointestinal irritation and unthriftiness. At their worst, they can lead to colic, intestinal ruptures, and death.
Using deworming agents on a regular schedule in combination with good management procedures is critical to relieving your horse of most parasites.