Canis ISSN: 2398-2942

Spider bites

Synonym(s): Arachnidism; Latrodectism (for Black Widow or Red Back; Loxoscelism (for Brown Recluse; Necrotic arachnidism (Loxoscelism and others

Contributor(s): Rosalind Dalefield, Dawn Ruben

Introduction

  • Venomous spiders are found in many countries including the USA and Australia.
  • Spider bites are considered rare but may be fatal, especially if multiple.

Pathogenesis

Etiology

  • Envenomation by means of a spider bite.

Predisposing factors

General
  • With the exception of the Sydney Funnel-Web spider, which is aggressive, most spiders bite in self-defense and will seek to escape rather than to bite.
  • Bites tend to occur when people or animals inadvertently sit or lie on a spider.

Pathophysiology

  • Latrodectusvenom contains alpha-Latrotoxin, a potent neurotoxin, and other toxins. The toxins are believed to bind to calcium channels, enhancing depolarization.
  • Epinephrine Epinephrine and norepinephrine release is increased and presynaptic reuptake inhibited.
  • Loxoscelesvenom contains a number of proteins including hyaluronidase, proteases, and hemolysins. The venom damages endothelia, and promotes intravascular coagulation and tissue necrosis.

Timecourse

  • Latrodectism: clinical signs may become apparent very shortly (10-60 minutes) after the bite, and progress rapidly but may take up to 8 hours to develop.
  • Loxoscelism: the initial bite is often not noticed and the lesion takes a few days to develop.

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

Other sources of information

  • Little P (1998) Spider Envenomation in Dogs and Cats. Clinical Toxicology, Proceedings 318,Post Graduate Foundation in Veterinary Science, University of Sydney.
  • Osweiler G D (1996) Toxicology. Williams and Wilkins.
  • Fowler M E (1993) Veterinary Zootoxicology. CRC Press.

 

Organisation(s)


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