Stongylus equinus

  

Contents

  

Rev: 10/16/2025

  Classification Biology and Ecology
Morphology and Anatomy Life Cycle
Return to Stongylus Menu Economic Importance Ecosystem Functions and Services
Distribution Management
Return to Strongylidae Menu Feeding  References
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Classification:

Chromadorea

Chromadoria

Rhabditida

Rhabditina

Strongyloidea

Strongylidae

Strongylinae
                  
Stongylus equinus Mueller, 1780
  •     Synonyms:
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    Morphology and Anatomy:

    Ref: Marchiondo et al., 2020

     

    Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
     
     
     

     

    Females:

    • 38-55 mm long, 1.8-2.3 mm wide.
    • Vulva is located 12-14 mm from the posterior end, about 2/3 body length from anterior.
    •  Eggs measure around 82 x 48 um

    Males:  

    • 26-35 mm long, 1.1-1.3 mm wide
    • Spicules slender, 2.6 mm long
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    Distribution:

    Worldwide

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    Economic Importance:

    Parasite of equines: horse, ass, mule, zebra.

     

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    Feeding:

    A voracious bloodsucking large strongyle occurring in the cecum of the horse, ass, mule, zebra, and other equids. (Marchiondo et al., 2020)
       
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    Biology and Ecology:

     

    Infective L3 are desiccation resistant and cold tolerant and can survive in pasture during a winter. They have a filamentous sheath and are ingested by a host animal during grazing.

     

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    Life Cycle:

    Direct lifecycle, do not require and intermediate host. Eggs are passed in feces and hatch as a free-living microbivorous L1 which feed on bacteria, develop and undergo two molts to the infective L3 stage. that develop and molt in 12 days to an L2 that molts finally to the infective L3.

    Ingested L3 penetrate the wall of the intestine and migrate via the portal vein to the liver. In the liver, they become encapsulated as nodules within the hepatic parenchyma. Larvae molt to the L4 in about 2 weeks and develop further in the liver during about 2 months. The L4 larvae then migrate beneath the peritoneum to the flanks of the animal (hence, the common name); hepatic ligaments, and the wall of the ventral abdomen. They molt to the young L5 which travel to the base of the cecum and form large purulent nodules that eventually rupture to release adult worms into the lumen of the caecum. The prepatent period until larvae become detectable in the host  is between 6 and  months.

    The L3 molt to L4 in intestinal nodules, similar to S. vulgaris. The L4 migrate to the right half of the liver where they feed and develop during 2 months before entering the pancreas or abdominal cavity to complete development to young adults.  The adults penetrate the wall of the large intestine and mate in the lumen. Eggs are released in the feces. The prepatent period is 9 months  (Marchiondo et al., 2020)

     

    Ecophysiological Parameters:

    For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters
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    Ecosystem Functions and Services:

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    Management:

    Anthelminthics are effective.

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    References:

    Beveridge, I., Spratt, D.M.  and Durette-Desset, M-C. 2014. Order Strongylida (Railliet and Henry, 1913). In Schmidt-Raesa, A. (ed). Handbook of Zoology: Gastroctricha, Cycloneurelia and Gnathifera. Vol 2. Nematoda. De Gruyter, Berlin

    Marchiondo, A.A., Cruthers L.R., Reinemeyer, C.R.  2020. Nematoda, Strongyloidea. Chapter 2 in Marchiondo, Cruthers and Fourie (eds) Parasiticide Screening Vol 2. Academic Press.

     

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    Copyright  1999 by Howard Ferris.
    Revised: October 16, 2025.