Animal Bite

Aka: Animal Bite, Mammalian Bite

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II. Epidemiology

  1. Dog Bites: 4.5 Million/year in U.S. (80-90% of Animal Bites)
  2. Cat Bites: 400,000 per year in U.S. (5-10% of Animal Bites)
  3. Human Bites: 250,000 per year

III. Risk Factors: Bite site infection

  1. Vascular compromise in affected wound
    1. Peripheral Arterial Disease
    2. Venous Insufficiency
    3. Lymphedema
    4. Longstanding Tobacco Abuse
  2. Distal extremity wounds have diminished vascular supply (Hand bite, Foot Bite)
  3. Bite site near a prosthetic joint
  4. Crush injury or Puncture Wound
  5. Cat Bite (long slender fangs risk deep space infection)
  6. Delayed presentation
    1. Arm or leg bite site >6-12 hours
    2. Facial bite site >12-24 hours
  7. Diabetes Mellitus or other immunosuppressed state

IV. HIstory

  1. Injury
    1. Wound sites
    2. Active bleeding
    3. Pain
    4. Weakness
    5. Numbness
    6. Fever or other signs of infection
  2. Animal
    1. Type of animal
    2. Animal behavior (provoked attack, aggressive behavior)
    3. Immunization status of animal
    4. Can animal be observed (e.g. pet or captured)
    5. Pre-evaluation wound management
    6. Animal control or police involvement
  3. Medical History
    1. Tetanus Immunization status
    2. Prior Rabies Vaccination
    3. Immunocompromised status (e.g. Asplenia, Chemotherapy)

V. Exam

  1. See Hand Exam
  2. Perform thorough skin exam
    1. Map bite locations
    2. Record bite dimensions including depth
    3. Document wound types (punctures, Lacerations, crush injuries)
  3. Identify Pitfalls
    1. Some wounds may not be initially evident (especially in younger children)
      1. Scalp and skull may hide significant injury under hair, behind ears or in skin folds
    2. Retained Foreign Body
    3. Infectious signs (erythema, edema, Lymphadenopathy, drainage)
    4. Neurovascular injury
      1. Extremity pulses and Capillary Refill
      2. Motor and senory exam
      3. Compartment Syndrome
    5. Structural injury
      1. Tendon Injury
      2. Open Fracture
      3. Joint penetration
    6. Facial Injuries (esp. orbital and periorbital wounds)
      1. Risk of ocular injury
      2. Proptosis
      3. Visual changes
      4. Orbital Cellulitis (and risk of Meningitis, Encephalitis, Brain Abscess)
      5. Facial Erysipelas

VI. Imaging

  1. XRay affected bite site
    1. Evaluate for Retained Foreign Body (esp. Avulsed Teeth)
  2. Head Imaging (e.g. Head CT)
    1. May be indicated in severe bites to the head
    2. Penetrating skull bites can generate enough force for Skull Fracture (risk of CNS Infection, abscess)

VII. Management: General

  1. Control bleeding first
  2. Provide analgesia and Anesthesia
    1. See Pediatric Analgesic
    2. Acetaminophen or Ibuprofen
    3. Consider Intranasal Fentanyl in children
      1. Dose: 2 mcg/kg intranasal (1/2 in each nostril) via MAD Atomizer
    4. Inject 1% Lidocaine through intact skin
  3. Clean wounds with soap and water if not already performed at home
  4. Copious Wound Irrigation with Normal Saline (or continous tap water irrigation under faucet)
    1. Set up 1000 ml saline bag with 20 gauge angiocatheter (or 20 ml or larger syringe)
    2. Place bag into BP cuff and pump up to 300 mmHg
    3. Irrigate wound with 1000 cc of Normal Saline
      1. Consider irrigation with dilute Povidone-Iodine solution if the animal is suspected to be rabid
    4. Do not use excessive pressure (may drive risk of infection to deeper tissues)
  5. Wound closure
    1. Indications for closure by Secondary Intention
      1. Cat Bite
      2. Human Bite
      3. Livestock bites
      4. Monkey bites
      5. Puncture Wounds
      6. Highly contaminated wounds
      7. Infected wounds
      8. Wounds older than 24 hours
      9. Crush wounds with structural injury (urgent Consultation)
      10. Distal extremity wounds with poor perfusion
      11. Immunocompromised patients
    2. Indications for Sutured closure (primary closure)
      1. Wound less than 12 hours old on extremities
      2. Wounds located on face less than 24 hours old
      3. No serious underlying injury
      4. Scalp Wounds
    3. Technique
      1. See Laceration Repair
      2. Debride devitalized tissue
      3. Explore wound carefully for associated injuries and foreign body
      4. Perform single layer closure
        1. Do not place deep Sutures
        2. Do not use Tissue Adhesive
  6. Wounds near joint or bone
    1. Obtain baseline XRay of puncture
    2. Obtain Orthopedic Consultation
  7. Wound exploration
    1. Explore wound for tendon, joint or bone injury
    2. Explore wound for foreign bodies (e.g. teeth fragments, which may break off in older animals)
      1. XRay wound if suspected Radiopaque Foreign Body
  8. Subspecialty Referral Indications
    1. Wounds near bone or joint
    2. Crush wounds with structural injury (e.g. Fracture, tendon Laceration)
    3. Infected wounds
    4. Wounds with significant edema
    5. Neurovascular injury or compromise (emergent Consultation)
    6. Deep structure involvement (especially on the face, extremities, hands)
  9. Immunization
    1. Tetanus Vaccine
    2. Rabies Prophylaxis
      1. See Rabies Postexposure Prophylaxis for full list of indications
      2. Indicated if dog or cat with Unknown Vaccination status
        1. Unprovoked attack
        2. Animal cannot be quarantined for 10 days
          1. Do not euthanize animal prior to completion of 10 day observation
      3. Immediate wound management (see Rabies Prophylaxis)
      4. Start Vaccine within 48 hours
  10. Antibiotic Prophylaxis
    1. See Bite Wound Antibiotic Prophylaxis

VIII. Prevention

  1. See Dog Bite

IX. Complications

  1. Skin Abscess
  2. Cellulitis
  3. Osteomyelitis
  4. Tenosynovitis
  5. Tendonitis
  6. Retained Foreign Body

X. References

  1. Cowling and House (2017) Crit Dec Emerg Med 31(5): 15-20
  2. Shivaprakash and Vezzetti (2022) Crit Dec Emerg Med 36(2): 3-10
  3. Ellis (2014) Am Fam Physician 90(4):239-43 [PubMed]

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