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large strongylesLarge Strongyles (aka Large Redworms)There are three major species of Large Strongyles, which are Strongylus vulgaris, S edentates, and S equinus. Of these, the most common is Strongylus vulgaris.

The large red worm (strongylus vulgaris) is a very serious parasite but is thankfully no longer very common.

The eggs are ingested by the horse and once hatched, they burrow into the walls of the gastrointestinal tract.

Migration through the blood vessels occurs, until mature, and can cause massive internal damage before they return to live in the intestinal wall. Large Strongyles are blood feeders and they ingest mucosal plugs as they move through the intestine. Anaemia can result from this blood loss.

LargeStrongyleCycle L

Heavy infection can result in:

  • Ulceration of the GI lining
  • Obstruction
  • Rupture
  • Anaemia
  • Un-thriftiness
  • Weight loss
  • Diarrhoea
  • Colic

Large Strongyles can be extremely dangerous to the horse. However, low resistance levels mean that control is relatively straightforward.

Which Actives Treat Large Strongyles
(aka Large Redworms)?

IvermectinMoxidectinIvermectin / PraziquantelMoxidectin / Praziquantel


Bimeda Equine is proud to promote best practice targeted worming regimes, to help protect both today’s horses and future generations.

To find out more about best targeted worming regimes, visit our Best Practice Advice section.

To view and download our materials, such as our Horse Owner’s Guide To Worming, visit out Library Section.

Contact Us - UK

Bimeda UK
Unit 2, Bryn Cefni Industrial Park,
Llangefni, Anglesey, Wales LL77 7XA
Phone: +44 (0) 1248 725400