Equis ISSN 2398-2977

Tapeworm infection

Synonym(s): Anoplocephala spp

Contributor(s): Sheelagh Lloyd, Craig Reinemeyer, Nicola Menzies-Gow


  • Endoparasitic disease of horses.
  • Cause: the equine tapeworms -Anoplocephala perfoliata,Anoplocephala magna Anoplocephala spp and Anoplocephaloides (Paranoplocephala) mamillana.
  • Signs: variable from none to colic.
  • Diagnosis: history, signs, serum or saliva ELISA, celiotomy,
  • Treatment: easily controlled or treated with endoparasiticides such as pyrantel pamoate at double the normal dose or praziquantel.



  • The main tapeworm seen in the UK and USA isAnoplocephala perfoliata  Anoplocephala spp.
  • Anoplocephala magna and Anoplocephaloides (Paranplocephala) mamillana may also be seen.

Predisposing factors


  • Young horses may be more susceptible having less resistance.


  • Horses are often asymptomatic.
  • Adult tapeworms have a predilection for the ileocecal junction and adjacent cecal mucosa, and can cause damage there. The severity of lesions seems related to the number of worms attached at the site.
  • Types of colic which have been linked to tapeworm infestation include intussusceptions Cecum: intussusception - cecocecal / cecocolic, cecal rupture Cecum: perforation, ileal impaction Ileum: impaction, ileal rupture and spasmodic colic Abdomen: pain - spasmodic colic.
  • It is postulated that presence of tapeworms secured to the mucosa in the ileocecocolic area can cause local effects → modulation of motility and/or impaction.
  • The tapeworms' suckers grasp plugs of mucosa. In light infections this leads to congestion and cell infiltration at the site of attachment. Heavier infections lead to a thickened, edematous, hyperemic, necrotic, ulcerated muscosa with cellular, particularly eosinophilic infiltration. There may be a fibrinous, eosinophilic, diptheritic membrane and sometimes nodular swellings.
  • Hypertrophy of the mucosa in the ileocecal area and adhered worms Anoplocephala perfoliata: ileocecal valve infestation 01 - pathology may → impaction colic Abdomen: pain - adult.
  • The inflammation and necrosis may affect muscular contractility and acetylcholinesterase produced by the worms could decrease parasympathetic transmission and decrease gut motility. The changes in motility could →  impaction colic Abdomen: pain - adult or intussusception Ileum: intussusception - ileocecal - pathology.


  • The pre-patent period is 6-10 weeks.


  • The life-cycle is indirect: the intermediate hosts are oribatid mite.
  • Mature tapeworms in the ileocecal area release gravid segments, containing eggs, which are passed in the feces.
  • The intermediate host - the free living oribatid (forage) mite - ingests the eggs and they develop into cysticercoids in about 3 months. Infected mites survive 8-9 months.
  • Infected mites are ingested by the horse when grazing pasture or hay and inside the horse these develop into mature tapeworms in 6-10 weeks Anoplocephala perfoliata: adult 02.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Abbott J B & Barrett E J (2008) The problem of diagnosing tapeworm infection in horses. Equine Vet Educ 40 (1), 5-6 PubMed.
  • Kjaer L N, Lungholt M M, Nielsen M K, Olsen S N & Maddox-Hyttel C (2007) Interpretation of serum antibody response to Anoplocephala perfoliata in relation to parasite burden and fecal egg count. Equine Vet J 39 (6), 529-533 PubMed.
  • Barrett E J, Blair C W, Farlam J & Proudman C J (2005) Postdosing colic and diarrhoea in horses with serological evidence of tapeworm infection. Vet Rec 156 (8), 252-253 PubMed.
  • Morgan E R, Hetzel N, Povah C & Coles G C (2004) Prevalence and diagnosis of parasites of the stomach and small intestine in horses in south-west England. Vet Rec 156 (19), 597-600 PubMed.
  • Craven J, Bjorn, Henriksen S A et al (1998) Survey of anthelminitic resistance on Danish horse farms, using 5 different methods of calculating fecal egg count reduction. Equine Vet J 30 (4), 289-293 PubMed.
  • Proudman C J, French N P & Trees A J (1998) Tapeworm infection is a significant risk factor for spasmodic colic and ileal impaction colic in the horse. Equine Vet J 30 (3), 194-199 PubMed.
  • Proudman C J & Trees A J (1996) Correlation of antigen specific IgG and IgG(T) responses withAnoplocephala perfoliatainfection intensity in the horse. Parasite Immunol 18 (10), 499-506 PubMed.
  • Proudman C J, Swan J D & Trees A N (1995) Efficacy of pyrantel embonate and praziquantel against the equine tapewormAnoplocephaloides mamillana. Vet Rec 137 (2), 45-46 PubMed.
  • Proudman C J (1993) Are tapeworms associated with equine colic? A case control study. Equine Vet J 25 (3), 224-226 PubMed.
  • Proudman C J & Edwards G B (1992) Validation of a centrifugation/flotation technique for the diagnosis of equine cestodiasis. Vet Rec 131 (4), 71-72 PubMed.

Other sources of information

  • Urqhart G M, Armour J, Duncan J L, Dunn A M & Jennings F W (1988) Veterinary Parasitology. Longmann Scientific & Technical. ISBN 0 5824 0906 3.
  • Rose R J & Hodgson D R (1993) Manual of Equine Practice. Saunders. ISBN: 0 7216 3739 6.