Horse Parasites: Meet The Family

So let's meet the family.

The Large Strongyles (Strongylus vulgaris and Strongylus edentatus). Also known as bloodworms, these guys are very bad news. As immature larvae, they migrate through blood vessels, destroy arterial walls, block or rupture blood vessels, impair circulation, and damage organ and tissues. The damage can result in colic, anemia, diarrhea, fever, lethargy, depression, and loss of appetite. To prevent bloodworms, use a dewormer that treats both adult worms and the more destructive arterial larvae. Ask your veterinarian for a recommendation, as many dewormers treat only the less dangerous adult worms.

The Small Strongyles. Small stronglyles live exclusively the intestinal tract. But don't let their name or limited territory fool you; small stronglyles can be dangerous if undetected. They can cause inflammation of the intestines, anorexia, weight loss, diarrhea and colic. A good dewormer is your best defense.

The Ascarids (Parascaris equorum), commonly known as roundworm. These unwelcome guests most commonly affect very young horses. In the larvael stage, they can damage lung and liver tissue. Symptoms include lethargy, coughing, fever, pneumonia and other respiratory problems. As adults, they live in the small intestine, causing problems like colic, ruptured gut, blockage and even death. As dangerous as they are, Ascarids are easily prevented with a horse parasite prevention program.

The Bots (Gastrophilus). OK, these don't have a very scary name. But they do have an interesting life. In the larvael stage, the bot fly lives inside the horse's stomach and/or mouth. As it reaches maturity, it leaves its comfy internal environment to live on the outside of your horse. There, it creates more little botfly larvae which are ingested by your horse. Bot flies can cause inflammation and sores in the mouth as well as stomach irritation and ulceration/perforation of the stomach wall. In extreme cases, bots can block stomach outflow into the small intestine, causing colic and possibly death. Treatment for bots, like the bots themselves, must involve both the inside and outside of your horse. First, you’ll need to treat the outside of your horse by removing bots. Learn equine bot fly removal techniques here. Follow this up with a dewormer for the internal bot fly larvae.

The Pinworms. (Oxyuris equi). Is your horse spending a lot of time itching and scratching her butt? She may be harboring pinworms. Equine pinworms live and mate in the rectum, and there's just not much to say about that but "wow" and "how do I get rid of them?". Deworm. Quickly. Because the less time you spend thinking about their unfortunate lifestyle the better.

The Intestinal Threadworms (Stronyloides westeri). Threadworms usually affect young horses. Diarrhea, lack of appetite, weight loss and haircoat problems are symptoms of threadworms. Many dewormers are not effective against threadworms so talk to your vet about these guys.

Summer sores (Habronema and Draschia) If a fly deposits larvae in the open skin or a wound on the horse’s body, the result is often summer sores. The larvae can cause conjunctivitis, nodules in the stomach wall, and gastritis. Fly control, deworming and manure management help to control summer sores.

So there you have it. An unpleasant group of guests, these horse parasites. But a routine parasite management program will keep your horse pest free and healthy with a minimum of effort.

Return From Horse Parasites To Horse Diseases