Equis ISSN 2398-2977

Pediculosis

Synonym(s): Lice infestation, nits

Contributor(s): Sue Paterson, Craig Reinemeyer, David Senter

Introduction

  • Pediculosis or lice infestation is a parasitic skin disease of horses.
  • Cause: lice - sucking liceHematopinus asiniand biting lice Damalinia equi.
  • Signs: pruritus and secondary excoriation, particularly of the mane and tail areas. Anemia may also occur.
  • Diagnosis: visualization of lice in the affected area.
  • Treatment: ectoparasiticides.
  • Prognosis: good.
Print off the Owner factsheet on Lice infestation to give to your clients.

Pathogenesis

Etiology

  • Biting and sucking lice .
  • Chewing/biting lice -Damalinia equi.
  • Sucking lice -Haematopinus asini.

Predisposing factors

General
  • Horses kept in close proximity.
  • Irregular grooming (lice lie dormant in fetlock feathers and submaxillary space).

Pathophysiology

  • Adult lice lay operculate eggs attached to hairs   →   adults on the host animal.
  • Lice are transmitted between horses by direct contact or by vectors such as grooming equipment and fence posts on which horses rub.
  • Nymphs and adults cause inflammation and pruritus by damaging the skin. Chewing/biting lice ingest skin flakes and serum; sucking lice live on blood.
  • The disease is compounded by self-excoriation and secondary infection.

Timecourse

  • Eggs (or nits) hatch into adults in 10-14 days.

Epidemiology

  • Seen more often in winter and early spring.
  • Host-specific and dependent.
  • 10-21 day life cycle.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hugnet C et al (1999) Interet du fipronil a 0.25 pour cent en spray dans le traitement de la phitiriose a Damalinia equie (pou mallophage). Prat Vet Equine 31, 65 VetMedResource.
  • Paterson S & Orrell S (1995) Treatment of biting lice in 25 horses using 1% selenium sulfide. Equine Vet Educ 7, 304 VetMedResource.
  • Foil L et al (1986)Parasitic skin disease. Vet Clin North Am Equine Pract (2), 403-437 (Review) PubMed.
  • Fadok V A (1984) Parasitic skin disease of large animals. Vet Clin North Am Large An Pract (1), 3-26 (Review) PubMed.

Other sources of information

  • Rose R J & Hodgson D R (1993) Manual of Equine Practice. Saunders. ISBN: 0 7216 3739 6.
  • 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.


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