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Flashcards in Equine Endoparasites Deck (27):

Name three cestodes of horses

Anoplocephala perfoliata

A. Magna

Paranplocephala mamillana


Name the intermediate host of cestodes.

Oribatid mite


Describe the lifecycle of A. perfoliata.

  • Infected mite ingested by the horse 
  • After 2 months adult worms are present at the ileo-caecal junction
  • Proglottids gravid with eggs are passed in horses faeces 
  • Proglottids disintegrate and release eggs which are ingested by oribatid mite
  • Eggs develop within the mite to cysticercoid
  • Mites are found in soil, shavings and hay (and are v small)

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Describe the morphology of A. perfoliata eggs.


~50-80 um 

Onchosphere is supported by pyriform apparatus 

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Describe the morphology of adult A. perfoliata.

Where in the equine SI are they found?

  • Short broad segments
  • Lappets behind each four suckers
  • Adults are found at the ileo-caecal junction

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What are the clinical signs associated with A. perfoliata infection?

What associated condtions?


  • Ulceration of intestine
  • Ill thrift
  • Enteritis 

Associated conditions:

  • Spasmodic colic
  • Itussuscpetion
  • Ileal impaction/ rupture


What ages are most affected by A. perfoliata?

Which time of year is most associated with A. perfoliata infection?

  • Less than three have highest level of infection but all ages are affected.
  • Autumn/ winter are peak levels but all times of year are possible.


How is A. perfoliata infection diagnosed in the horse? 

  • FEC (only around 60% sensitivity)
  • ELISA detects Ag (95% specificity)
    • Parasite excretory/secretory Ag
    • IgG 


Describe a treatment plan for A. perfoliata infection.

Double dose pyrantel



Giant roundworm 




Which stage of the ascarid lifecycle is infective?

L2 found within the egg


True or False.

Ascarid eggs are highly resistent to death outside the host.



Where in the horse can Ascarids be found?


What are the potential effects of the infection?

  • Small intestine
    • Compete with horse for nutrients 
    • May cause mechanical blockage
  • Migrating - hepato-tracheal migration 
    • Stimulates ++ inflamm response


Describe the morphology of a Parascaris equorum egg.

Round and thick walled with undiff morula in the centre.

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Outline the lifecycle of Parascaris equorum.

  • Eggs are passed onto pasture
  • L2 develops within the egg (takes about 4 weeks but is temp dependent)
  • Egg is eaten by the horse
  • L2 migrates to the liver and then lung, developing to L3 
  • L3 is coughed up and reswallowed, develops from L4-L5 in the SI

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The period of time from infection until mature adult parasites are producing eggs or larvae.


What is the PPP of Parascaris equorum?

Around 12 weeks


What clinical signs are associated with Parascaris equorum?

  • Typically foal infection 
    • foals can spread to other foals but adults are generally immune
  • Transient cough
  • Ill thrift and poor wt gain
  • XX diarrhoea
  • GI obstruction in heavily infected animals 


How can Parascaris equorum be controlled in the horse?

Resistence to which anthelmintic has been reported?

Anthelmintics and pasture rotation (remember wggs are very resistent)

Ivermectin resistence 


Describe the morphology of Oxyuris equi eggs and adult.

  1. Egg: 80um, oval shaped with a slightly pointed edge
  2. Adult: 1-10cm with a pointed tail

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In which part of the equine GI tract would Oxyuris equi be found?

Large intestine 


Outline the lifecycle of Oxyuris equi.

  1. Female lays eggs on the perianal skin 
  2. Eggs fall on the ground
  3. L3 develop in the egg
  4. L3 ingested and develop in the LI mucosal crypts 
  5. Adults present in the LI lumen

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What is the PPP of Oxyuris equi?

5 months


Anal rust and pruritis are associated with which equine parasite?

Oxyuris equi


How can Oxyuris equi be diagnosed and treated?

Selotape test on perianal area

Anthelmintics though limited efficacy


What is meant by a extraneous parasite?

Name two examples in the horse.

Of little consquence..

Triodontophorus spp and Trichostrongylus axei


Pathogenesis of extraneous parasites?

Describe the morphology of their eggs?

  • Contribute to the damage caused by adult worms of other species 
  • Feed in groups

Eggs are similar to other strongyles but twice the size