Equine parasites are with us every day of the year, as they lay eggs that hatch into larvae that turn into adult worms that start the process all over again. With the arrival of springtime, many horses are returning to pastures which are one of the major sources of parasites in horses.
Environmental control - A necessity for horse parasite control
Horses ingest parasites in pastures and from streams leading to conditions that can jeopardize the horse's internal organs and the horse's life.
During their passage through the horse's system, these parasites injure organ systems and create problems that lead to anemia, diarrhea, weight loss, nutritional deficiencies, and other conditions that jeopardize the life of your horse.
In addition, researchers estimate that worms are a predisposing factor in 90 percent of cases of intestinal colic.
Fortunately, dewormers rank very high in medical advancements made over the last few years, and horses, in general, are healthier as a result. When things go well, it's easy to become complacent about the routines that have taken us this far. Don't let that happen to you when it comes to the important strategies of an effective deworming program.
The most common worms that are destructive to your horse's health include:
- Large Strongyles (Bloodworms): Infection rate is between 70 and 100 percent of all horses. They can destroy arterial walls, blood vessels, impair circulation, and lead to colic, anemia, diarrhea, fever, poor condition, brain damage, and other disorders.
- Small Strongyles: Larvae penetrate the walls of the intestine, where they encyst, leading to inflammation that results in anorexia, weight loss, and chronic colic. When the larvae emerge from the gut wall in spring or in times of stress, they cause severe diarrhea.
- Ascarids (Roundworms): These parasites grow up to 12 inches in length, can cause colic, heart damage, liver and lung damage, and, in older horses and foals, can injure the intestines.
- Stomach Bots: Virtually all horses are infected. Eggs are deposited on hairs near the mouth and hatch into larvae, which find their way into the mouth. They burrow into pockets between the molar teeth, causing dental disease, are swallowed, and then attach themselves to the lining of the stomach where they cause irritations, ulcerations, and perforations of the stomach wall.
- Pinworms: These small worms cause intense anal itching, leading to attempts by the horse to decrease the itching by rubbing its tail and hindquarters against a post or wall, eventually damaging the hair, skin, and tail. A large number of pinworms can cause inflammation of the colon and episodes of colic.
- Tapeworms: These large worms may cause severe ulcerations of the large intestine.
- Stomach Worms (Habronema): Most common problems are larval attacks that cause summer sores on the skin and conjunctivitis in the eyes. These small worms live in colonies in the wall of the stomach and can produce severe gastritis and, in some cases, tumor-like enlargements in the stomach wall. If the stomach wall ruptures, peritonitis may occur.
- Hairworms (Small Stomach Worms): Severe infestation produces gastritis, with ulcers, weight loss, and anemia.
Get Rid of Parasites Before They Become a Problem
The American Association of Equine Practitioners has compiled a list of environmental ways to get rid of parasites:
- Pick up and dispose of manure droppings in pastures at least twice a week.
- Mow and harrow pastures regularly to break up manure piles and expose parasite eggs and larvae to the elements.
- If possible, rotate pastures, allowing sheep and cattle to graze intermittently to interrupt the life cycles of parasites.
- Group horses by age to reduce exposure to certain parasites and maximize the effectiveness of a deworming program geared for that group.
- Keep the number of horses per acre to a minimum to prevent overgrazing and to reduce fecal contamination.
- Use a feeder for hay and grain instead of feeding on the ground.
- Remove bot eggs quickly and regularly from the horse's haircoat to prevent ingestion.
- Rotate deworming agents, not just brand names, to prevent chemical resistance.
- Quarantine new arrivals for at least three weeks and deworm them with ivermectin. After that, put them on the same deworming schedule as other horses.
- Perform fecal examinations 14 days after deworming. In a successful program, horses should not be passing parasite eggs at 14 days.
- Whatever program you choose, Stick With It!