What is the appropriate management of a dog bite wound contaminated with a nail fragment?

Management of Dog Bite Wounds Involving the Nail

Dog bite wounds involving the nail bed or nail apparatus require immediate thorough irrigation and debridement, empirical antibiotic therapy with amoxicillin-clavulanate, tetanus prophylaxis if not current within 10 years, and should generally be left open rather than primarily closed due to high infection risk associated with hand injuries and puncture-type wounds. 1, 2

Immediate Wound Management

Wound Cleaning and Exploration

• Copiously irrigate the wound with normal saline using a 20-mL or larger syringe or 20-gauge catheter to generate adequate pressure for effective cleaning 3, 4
• Perform careful debridement of all contaminated and devitalized tissue 5, 6
• Thoroughly explore the wound for:
  • Foreign bodies (nail fragments, tooth fragments, dirt) 3
  • Tendon involvement 4
  • Bone or periosteal penetration 1
  • Joint capsule violation 6
• Document neurovascular function including pulses, sensation, and range of motion of adjacent joints 3

Wound Closure Decision

Wounds involving the nail and hand should NOT be primarily closed 5, 1. The evidence strongly supports leaving these wounds open because:

• Hand wounds carry significantly higher infection rates than wounds on other body parts 1, 7
• Puncture wounds (common with nail involvement) are high-risk for deep infection 1, 8
• Cat bites and infected dog bites involving hands should be left open after debridement 8

The only exception to avoiding primary closure is facial wounds, which may be closed after copious irrigation, cautious debridement, and preemptive antibiotics 5. Hand and nail bed injuries do not fall into this exception category.

Antibiotic Therapy

First-Line Treatment

• Amoxicillin-clavulanate is the antibiotic of choice for empirical treatment 1, 3, 4
• This combination effectively covers the polymicrobial flora of dog bites, including Pasteurella species (present in 50% of dog bites), staphylococci and streptococci (40%), and anaerobes 1
• Antibiotic prophylaxis should be strongly considered for all dog bites, particularly those involving the hand, puncture wounds, and wounds involving deeper structures 3, 4

Alternative Regimens for Penicillin Allergy

• Doxycycline 100 mg twice daily provides excellent coverage against Pasteurella multocida 1
• Fluoroquinolones (ciprofloxacin, levofloxacin) plus metronidazole for anaerobic coverage 1
• Moxifloxacin 400 mg daily as monotherapy covers both aerobes and anaerobes 1

Antibiotics to AVOID

Do not use the following as they have inadequate coverage for bite wound pathogens:

• First-generation cephalosporins like cephalexin 1
• Penicillinase-resistant penicillins like dicloxacillin 1
• Macrolides like erythromycin 1
• Clindamycin as monotherapy 1

Tetanus Prophylaxis

Administer tetanus toxoid if the patient has not received vaccination within 10 years 5, 2. For dog bite wounds involving the nail (considered a "dirty wound"):

• If >5 years since last tetanus dose: give Td or Tdap booster 2
• If <3 doses or uncertain vaccination history: give both tetanus toxoid AND tetanus immune globulin (TIG) 2
• Tdap is preferred over Td if the patient has not previously received Tdap 5

Complications to Monitor

Watch carefully for these serious complications, especially with nail bed and hand involvement:

• Pain disproportionate to injury severity near bone or joint suggests periosteal penetration 1
• Septic arthritis requiring 4-6 weeks of antibiotic therapy 1
• Osteomyelitis requiring prolonged treatment 1
• Tendinitis and abscess formation 1
• Capnocytophaga canimorsus bacteremia (particularly dangerous in asplenic or cirrhotic patients) 1

Imaging Considerations

• Imaging is not routinely required unless there is suspicion of retained foreign body, underlying structural damage, or extensive injury 3
• Consider radiographs if bone involvement is suspected based on depth of injury or disproportionate pain 1