Internal parasites come in many forms. They can affect your horse throughout the parasitic life cycle and can thrive in pastures where your horse grazes, exercises and plays.
LARGE STRONGYLES (Bloodworms)
• Horses shed most eggs in manure, which are then ingested from contaminated soil.
• Adults located in the large bowel.
• Can cause significant damage to the gut, which may result in weakness and diarrhoea.
SMALL STRONGYLES (Redworms / Cyathostomes)
• Horses shed most eggs in manure, which are then ingested from contaminated soil.
• Adults located in the large bowel.
• Interfere with digestion.
ROUNDWORMS (Ascarids)
• Eggs are ingested through contaminated soil.
• Adults located in the small intestine.
• Interfere with nutrition and can cause colic, diarrhoea and coughing.
• P. equorum - major concern in young horses.
PINWORMS (Oxyuris spp.)
• Eggs are shed in manure, which are then ingested from contaminated soil.
• Live in large intestine.
• Eggs are laid around the horses anus, causing the horse to scratch their tail constantly, leading to possible injury.
HAIRWORMS (Trichostrongylus axei)
• Eggs are shed in the manure, which are then ingested from contaminated soil.
• Found in stomach and small intestine.
• Can cause bleeding in intestines.
• Foals are very susceptible.
• Can survive in sheep and cattle.
LUNGWORMS (Dictyocaulus arnfieldi)
• Found in the horses airways.
• Eggs are coughed up and swallowed.
• Can cause a severe cough.
• Horses are more susceptible when run with donkeys.
TAPEWORMS (Anoplocephala spp.)
• Acquired by ingesting small mites present in the pasture.
• Found in the ileocecal junction (where the large intestine meets the small intestine).
• Large burdens can cause blockages.
INTESTINAL THREADWORMS (Strongyloides westeri)
• Mostly effects foals <6 months as they contract the worms through the mothers milk.
• Larvae may cause bleeding and respiratory problems.
• If left untreated can cause diarrhoea, weakness and loss of weight.
NECK THREADWORMS (Onchocerca spp.)
• Worms lay live larvae which is deposited by midges on skin and wounds.
• Can travel into ligaments and tendons.
• Dead worms remain in affected tissues, visible as raised bumps.
LARGE MOUTH STOMACH WORM {Habronema muscae)
• These worms lie in the mucus in the stomach.
• Eggs are then passed in manure and are ingested by maggots of flies.
• Flies/larvae are then ingested by the horse, when flies migrate around the horses mouth.
• Larvae on the eyes can lead to conjunctivitis and larvae in the wounds can lead to summer sores.
BOTS {Gastrophilus spp.)
• Bots are larvae of flies.
• Flies lay eggs on horses’ legs, the eggs then hatch when the horse rubs its legs.
• Active in Summer and Autumn.
• Large number of bots in the stomach may damage the stomach lining.
• Treat for bots in late May and late August.
The control of internal parasites is no small part in the overall investment of your horse’s health. Educated decisions made when it comes to worming treatments, will help to protect against parasitic disease and associated medical problems.
The responsible use of wormers can also assist in slowing down the development of resistance to current active ingredients. Therefore a calculated worming program is a pivotal part in the overall investment in your horses health.