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Infections usually localized to the site of a bite. Rare sequelae include meningitis, brain abscess, endocarditis, and septic arthritis.


  • Infection in 10–15% of dog bites and approximately 50% of cat bites

  • Greatest rate of infection after bites to the hands (28–63%)

    • ✓ Other common sites: Face/head/neck (6–16%), arm/leg (10–32%), and trunk (2–10%)


  • Usually polymicrobial; derived from oral flora of biting animal

  • Cat and dog bite infections: Pasteurella canis (dog), Pasteurella multocida (cat), Capnocytophaga spp (dog) streptococci, Staphylococcus aureus, Moraxella spp., Neisseria spp., and anaerobes

  • Human bites: S. aureus, viridans group Streptococci, Streptococcus pyogenes, Eikenella corrodens, Streptococcus intermedius, Neisseria spp., Haemophilus spp.

  • Horse/sheep bite: Actinobacillus spp, Streptococcus equisimilis

  • Marine settings/fish bite: Halomonas venusta, Vibrio spp, Aeromonas hydrophila, Plesiomonas shigelloides, Pseudomonas spp., Mycobacterium marinum

  • Monkey bite: B virus


  • Infection follows direct inoculation of bacteria into tissues.

  • Hematogenous dissemination may occur.

Clinical Manifestations

  • Note wound type (puncture, laceration, avulsion), edema, erythema, tenderness, drainage, depth of penetration, bruising, deformity, involvement of underlying structure, sensation, regional lymphadenopathy.

  • Look for signs of systemic infection (e.g., fever, hypotension).

  • Animal: Record type of animal, health of animal, provoked or unprovoked attack; observe for signs of rabies if applicable.

  • Patient: History of asplenia (increased risk of Capnocytophaga spp.); immunosuppression or other illnesses; last tetanus immunization


  • Gram stain and culture of wound if time from injury is longer than 8 hours or if signs and symptoms of infection exist.

  • Consider blood culture if fever present.

  • Radiography indicated for penetrating injuries overlying bones or joints, suspected foreign body, or fracture.


Immediate Management

  • Examine for foreign body, irrigate with copious amounts of normal saline, and debride devitalized tissue.

  • Suturing is controversial. Leave wound open if greater than 8 hours old or a puncture wound; primary wound closure for injuries to face and when cosmetic outcome is important

  • Indications for operative exploration and debridement: Extensive tissue damage; involvement of metacarpophalangeal joint from clenched fist injury; cranial bites by large animals

Tetanus Prophylaxis

  • Clean minor wounds: Administer tetanus toxoid if >10 years since last tetanus-containing vaccine dose, if vaccine history is unknown, or if fewer than three doses received.

  • Puncture or severe wounds: If fewer than three doses received, administer tetanus toxoid and tetanus immunoglobulin. If patient has completed primary immunization but it has been ≥5 years since last tetanus-containing vaccine dose, administer tetanus toxoid.

Rabies Postexposure Prophylaxis

  • Prophylaxis:

    • ✓ Active: Four doses of rabies vaccine on days 0, 3, 7, and 14 (five doses for immunocompromised hosts)

    • ✓ ...

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