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Parasites in Horses


Two broad categories:

The roundworms or nematodes (circular section)

Large strongyles

to the most frequent and most dangerous horse. They occur throughout the year, especially in young horses and adults, they live on pasture or in stables.

Small strongyles

dangerous to increasingly encountered in recent years among young horses, adults and older horses, grazing or at the box.


primarily affect foals in terms of frequency and severity of the infestation.


concern mainly young horses and can cause more digestive problems, respiratory symptoms.


are found mainly in horses and older adults with access to a box and are often accompanied by an abrasion horsehair tail associated with anal itching

Tapeworms or cestodes (flat section)


Anoplocephala perfoliata is the most common tapeworm in France. It occurs mainly in autumn and winter and can cause serious digestive problems.

Fly larvae


Deworming schedule

Mid December - Mid January Flatworms (tapeworms)
Mid March - Mid April Roundworms or nematodes:
Large strongyles - Small strongyles - Ascaris - Pinworms
Mid June - Mid July Roundworms or nematodes:
Large strongyles - Small strongyles - Ascaris - Pinworms
Mid September - Mid October Roundworms or nematodes + bots

Ideally, for optimum protection should be dewormed every 6 weeks.

Hygiene measures

  • When deworming, respect the doses
  • Worming a horse "newcomer" before introducing the group
  • To rotational grazing
  • Wash thoroughly boxes at least twice a week to prevent reinfection of horses from the eggs of their own dung
  • Treat all horses for the same group at the same time
  • Follow a program of annual deworming
  • Remove wet areas by drainage