Mammalian Bites

Basics

Description

Injury to the human skin and/or subcutaneous tissues caused by bite, causing local, and in some cases systemic, effects

Epidemiology

  • Animal bites
    • Approximate frequency
      • Dogs: 90–95%
      • Cats: 3–8%
      • Rodents or rabbits: 1%
      • Raccoons and other animals: 1%
    • 90% of the offending animals are well-known to the victim.
    • Children are the most common victims:
      • Boys are twice as likely as girls to be bitten by dogs.
      • Girls are more likely to be bitten by cats.
  • Human bites
    • Most common in children ages 2–5 years
    • In older children, bites may occur accidentally during sports activities or intentionally during altercations or abusive situations.

Incidence

  • An estimated 4.5 million dog bites and 400,000 cat bites occur annually in the United States.
  • The incidence of human bites is unknown due to underreporting.

General Prevention

  • Ensure that children receive routine immunizations against tetanus and hepatitis and that family pets are immunized against rabies.
  • Encourage children to avoid contact with wild animals and dead animals.

Pathophysiology

  • Injury associated with bite types:
    • Dog
      • Crush and tear injuries
      • May involve bone
    • Cat
      • Puncture-type wounds
      • Penetrate deeper and carry a higher risk of infection
    • Human
      • Generally only violate skin
      • However, penetration into joint and tendon sheath spaces may occur (especially bites overlying the metacarpal-phalangeal areas).
  • Infection
    • Rate of infection
      • Dog bites: 3–18%
      • Cat bites: 28–80%
      • Human bites: 15–20%
    • More recent studies have suggested an incidence of infection after dog and cat bites to be closer to 2–3%.
    • Infections are most commonly polymicrobial with both aerobic and anaerobic organisms.
    • Infected dog and cat bites
      • Pasteurella species are the most frequent isolates.
      • Dog: Pasteurella canis
      • Cat: Pasteurella multocida and Pasteurella septica
      • Common anaerobes include Fusobacterium, bacterioids, Porphyromonas, and Prevotella.
    • Infected human bites
      • Streptococcus anginosus
      • Staphylococcus aureus
      • Eikenella corrodens
      • Fusobacterium species
      • Prevotella species

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