Ascarids and Lungworms-The Monsters Inside

During the life of a foal especially under 18 months of age it is extremely important to use an effective deworming protocol.

One of The Most life threatening worms that threaten the life of a young horse is Ascarids, also known as roundworms. The issue with Ascarids is the fact that they are extremely adept at migrating and can travel easily through the bloodstream in their juvenile phase. This migration allows them to pass through a young horse’s liver and lungs before returning to the small intestine to mature. Left to their own devices without owner intervention an Ascarid infection can wreak havoc on the respiratory system, the liver and even cause stunted growth, lethargy and death. Mature Ascarids are also notorious for causing intestinal impaction. The most common Ascarid to infect horses is Parascaris equorum. Females lay sticky eggs out in the pasture that are encased in a very tough protective shell. This allows them to have an excellent chance of survival, even in freezing temperatures or extremely dry conditions. They are just sitting out there in the grass waiting for a horse to eat them along with the blades.

A heavy Ascarid burden in the intestinal tract will likely show up in a foal as a pot bellied look, a thin appearance, a rough coat and an extremely docile foal.

While the juvenile roundworms are migrating respiratory symptoms may develop that can mimic pneumonia. However, the fever, nasal cough and/or nasal discharge will not be affected at all by antibiotics

. Typically adult horses develop an immunity to Ascarids but there have been cases where young mature horses have not been able to fight it off. Bloodwork in these adults can show unexplained liver damage and the mature horse may present with a chronic cough where other causative factors have been ruled out. Upon autopsy of such horses liver and lung scarring has been noted.

Dictyocaulus arnfieldi is another type of roundworm that can cause pneuomonia like symptoms in horses. In layman’s terms these are known as lungworms. Lungworms can be very difficult to distinguish from other respiratory diseases. Additionally lungworms can be hard to diagnose because their larvae often does not pass into the feces. Frequently this condition is diagnosed by ruling out all other things and bronchoscopy and endoscopy which can be very useful tools in diagnosing lungworm. Equines that have grazed along side donkeys show a higher incidence of lungworm infestation because for some reason donkeys are a better host for these female worms.

Deworming your foals properly is vital to the animal’s long term health and to reducing the incidence of herd spread and parasite resistance. If you find yourself with a foal, please find a veterinarian who is well versed in such matters and helps you develop and effective deworming protocol.