Strongyles, commonly known as bloodworms, are highly dangerous to horses. There are three major different types: single toothed, toothless, and large strongyle. The beginning of their lifecycle is for the most part, the same until they enter the horse’s body.
SINGLE TOOTHED STRONGYLE:
This is the most severe of the stronglyes. It burrows through the intestine wall and goes into the arteries (specifically the artery that supplies blood to the intestine, the anterior mesenteric artery). When it burrows through the arterial wall, the wall weakens and causes the artery to balloon, called an aneurysm. The weakened area then has a risk of rupturing which would cause the horse to bleed to death. Tissues could also become inflamed and plug the artery, called a thrombus. If the flow of an artery stops, called an infarct, the tissue that isn’t receiving blood will die and the horse will suffer severe colic with a high risk of dying without surgery. This process can take at least 6 months.
It leaves the intestines, goes to the liver, to the tissues around the liver, then back to the large intestine. This journey causes damage to the liver which leads to colic. The larvae carry bacteria which causes serious infections through the tissues they travel through. They also can rupture blood vessels and cause hemorrhaging so bad that the horse could die. Their trip can take as long as 300 days.
It leaves the intestine and goes to the liver and the pancreas. It burrows into and damages these organs along with causing infections. It’s trip takes about 240 days.
THE EGGS AND PREVENTION:
There at least 12 species of strongyles that do not cause disease but lay eggs similar to the severe three types I just discussed. This causes difficulty when diagnosing. The eggs favor conditions with moderate heat, moisture, and shade and can survive a year in these conditions. They are able to hide in blades of grass where they can be eaten.
For prevention, allowing horses to graze in hotter and dryer conditions and take them away from grazing at dusk can reduce the chance of catching worms. Also, make sure you deworm your horse the adequate amount.