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animal_bites

animal bites in Australia

introduction

  • ~64% of Australian households have a pet
  • ~50% of Australians will have an animal bite in their lifetime
  • ~2% of Australians will be bitten in any one year with 1-2 dying from an animal bite (usually children bitten on head and neck)
  • 85-90% of animal bites are dog bites, 5-10% are cat bites, 2-3% are human bites, 2-3% are rodents.
  • ~100,000 will be injured from dog attacks each year with 13,000 seeking treatment in hospital
  • children aged < 5yrs are at greatest risk of dog bites and are often bitten on the face, whereas adults tend to be bitten on upper limbs from freely roaming dogs.
  • ~75% of dog bites are caused by 5 of the 160 available breeds even though they account for only 31% of the dog population:
    • German Shepherds, Pit Bull Terriers, Blue/Red Heelers, Dobermans and Rotweillers.
    • these breeds are 4-5x more likely to bite than other breeds but other factors contribute such as training and neutering.
  • surveys have suggested that 50% feared dog attacks and 21% modified their behaviour towards dogs
  • most cat bites occur in women and are often unprovoked.

Mx of animal bites

assess wound

  • document fang penetration
  • consider XRay to exclude fracture, bone penetration, animal tooth remnants
  • explore wound to exclude involvement of deeper structures
  • if wound is clinically infected, take cultures and specifically request:
    • aerobic and anaerobic cultures
    • fastidious organisms
    • extended incubation
    • common causal organisms:
      • dog bites (~18% become infected):
        • Pasteurella dagmatis, canis (50%)
        • Staph aureus/intermedius, Streptococcus sp, Moroxella sp, Neisseria sp
        • Capnocytophaga canimorsus (4.7%) - risk of severe sepsis in immunocompromised or asplenic patients
      • cat bites (28-80% become infected):
        • Pasteurella multocida (75%)
        • mixed aerobes and anaerobes
        • Bartonella henselae, the cause of cat-scratch fever can be transmitted by scratch or bite of infected cat (30% of cats) or cat flea.
      • rodents (10% become infected)
        • Streptobacillus moniliformis and Sprillum minus cause rat bite fever charcaterised by triad of fever, rash & arthritis and most respond well to Rx with penicillin or doxycycline
      • human bites
        • Strept viridans, Group A Strept, anaerobes, Eikenella, Hep B/C and rarely HIV / AIDS

prophylaxis and wound Mx

  • tetanus prophylaxis
  • if Australian bat lyssavirus exposure
  • rabies prophylaxis if bitten in rabies-prone country
  • cleanse wound
    • use copious quantitities Normal saline or water under high pressure
  • consider primary wound closure if presentation < 10hours post-bite
    • controversial as risk of infection
    • if facial wounds then generally refer to plastics for opinion
    • if possible penetration into a joint then refer to orthopaedics for consideration of joint washout
  • reduce swelling:
    • elevate limb
    • immobilise limb
  • consider prophylactic antibiotics if high risk wound
    • controversial
    • metanalysis seems to show relative risk of infection is 0.56 (0.32-0.82 CI) with antibiotics with absolute benefit of 1 infection prevented per 14 treated (Cummings. Ann Em Med (1994) 23:535-40).
    • high risk wounds:
      • puncture or crush wound
      • hands, feet, face
      • penetration of underlying tissues (bone, joint, tendon sheaths (esp. puncture wounds on fingers), vascular)
      • prosthetic joint
      • delayed presentation > 8hr
      • immunocompromise
    • choice of antibiotic
      • amoxycillin + clavulanate bd for 5 days
  • antibiotics if infection established:
    • metronidazole 10mg/kg up to 400mg o bd for 14 days, PLUS EITHER
      • cefotaxime or ceftriaxone 50mg/kg up to 1g iv daily for 14d, or,
      • if immediate penicillin HS, then:
        • doxycycline 200mg 1st dose then 100mg bd if age > 8yrs, or,
        • cotrimoxazole bd, or,
        • ciprofloxacin 10mg/kg up to 500mg o bd
    • alternatively, can use either:
      • piperacillin + tazobactam 8h for 14d, or
      • ticarcillin + clavulanate 6h for 14d
  • consider hep B/C and HIV Mx if high risk human bites
  • consider non-accidental injury if child with human bites and intercanine distance > 3cm

disposition

  • patient education
    • warning signs of infection
    • prevention of bites
      • avoid purchasing dangerous breeds
      • sterilization of male dogs
      • dog training, particularly puppy socialisation
      • familiarising the dog to children
      • lead use
      • encourage children to approach dogs cautiously
      • don't leave young children alone with dogs
      • hand wash after handling animals +/- wear gloves
      • early wound cleaing after bites
      • immunise bat handlers
      • warn immunocompromised or asplenic patients to seek Rx early after any bite
  • patient review in 24-48hr

references

  • Dendle & Looke. Em Med. Aust. (2008) 20, 458-467.
animal_bites.txt · Last modified: 2016/11/25 21:57 (external edit)