Ascarids (roundworm) - Internal Parasites

Ascarids or roundworm infections are primarily a problem of young horses. They seldom cause significant damage in animals that are 11 years or more old. They are primarily found in the small intestine.

How your horse becomes infected:
Infective eggs are taken in with contaminated feed and water. The eggs hatch in the small intestine and the microscopic larvae penetrate the intestinal wall, enter the blood stream, and are carried to the liver and lungs.

Health effects::
Heavy numbers of larvae can cause severe inflammation and destruction in the liver and the lungs. After approximately one week in the lungs the larvae move up the trachea, are coughed up and swallowed again. When they reach the small intestine the second time they quickly mature, become adult worms, and produce eggs. While ascarids do not attach themselves to the intestinal wall as the strongyles, they do utilize a great deal of food, excrete toxic wastes, depress growth and development, cause digestive disturbances, and produce potbelly.

The eggs pass out in the manure but do not hatch outside the host. They do embryonate and become infective in 10-14 days. The eggs are quite resistant, especially to drying and freezing, and can remain alive and infective for 5 years or longer. Heat is harmful to them and the hot, dry weather of summer or the heat generated in composting can destroy many. Lye is also effective in destroying ascarid eggs.