Strongyles - Internal Parasites

The strongyles, or blood sucking worms, feed on blood from the host animal. They are found in the intestines where they cause extensive damage to the blood vessels and the mucous membrane. The loss of blood results in anemia and makes the animal. more susceptible to bacterial infections.

How your horse becomes infected:
The infective larvae are ingested when the horse grazes on contaminated pastures or eats contaminated feed. The larvae migrate extensively, causing damage to many organs and tissues (particularly to the walls of blood vessels which may develop aneurysm and eventually cause death). The larvae of one species of strongyle may penetrate the walls of arteries particularly, those that supply blood to the intestines, causing recurrent colic. The larvae require 6-1/2 to 8 months to reach maturity. The adult parasites then migrate to the large intestine and remain there during their adult life.

Health Effects:
The adult worms penetrate the intestinal wall, attach themselves to small blood vessels, and thus secure the blood necessary for them to survive. The injury to the intestinal wall results in interference with the digestion and absorption of food, as well as loss of blood. The adult females lay thousands of eggs daily and these pass out of the body in the manure.

When the temperature is 75 to 800 F, the eggs hatch in approximately 20 hours. The resulting free-living larvae develop into the infective stage in 5-6 days. They are then capable of infecting the horse when ingested and must be ingested to complete the life cycle. Freezing stops the hatching of the eggs and the development of the larvae but does not kill either. Heat generated by composted manure kills both. Larvae live about 3 months on the average but may live for a year or even longer in moist, cool climates.