What is the recommended antibiotic dosage for a dog bite?

Antibiotic Dosage for Dog Bite Management

For dog bite wounds, amoxicillin-clavulanate 875/125 mg twice daily orally is the recommended first-line antibiotic treatment for adults. 1

Patient Assessment and Risk Stratification

Dog bites require prompt evaluation to determine infection risk and appropriate management:

• High-risk bites (requiring antibiotics):

  • Immunocompromised patients
  • Asplenic patients
  • Patients with advanced liver disease
  • Wounds with preexisting or resultant edema
  • Moderate to severe injuries
  • Injuries to the hand or face
  • Injuries that may have penetrated periosteum or joint capsule
  • Puncture wounds
  • Presentation >8-12 hours after injury
  • Wounds that have undergone primary closure 1, 2

• Low-risk bites (may not require antibiotics):

  • Superficial wounds
  • Non-puncture wounds
  • Immunocompetent patients
  • Prompt presentation (<8 hours after injury)
  • Wounds not involving face, hand, or foot 1

Antibiotic Recommendations

First-line therapy:

• Adults: Amoxicillin-clavulanate 875/125 mg twice daily orally for 3-5 days 1, 3, 4
• Children: Amoxicillin-clavulanate 45/6.4 mg/kg/day divided twice daily 4

Alternative options for penicillin-allergic patients:

• Doxycycline: 100 mg twice daily orally (excellent activity against Pasteurella multocida) 1, 3
• Combination therapy: Trimethoprim-sulfamethoxazole (160-800 mg twice daily) plus metronidazole (250-500 mg three times daily) 1
• Clindamycin: 300 mg three times daily (but misses Pasteurella multocida) 1

Intravenous options (for severe infections):

• Ampicillin-sulbactam: 1.5-3.0 g every 6-8 hours
• Piperacillin-tazobactam: 3.37 g every 6-8 hours
• Carbapenems (ertapenem, imipenem, meropenem) 1

Microbiology Considerations

Dog bite wounds typically contain mixed flora:

• Pasteurella species (found in 50% of dog bites)
• Staphylococci and streptococci (found in ~40% of bites)
• Anaerobes (Bacteroides, fusobacteria, Porphyromonas, Prevotella)
• Capnocytophaga canimorsus (can cause fatal sepsis in asplenic or liver disease patients) 1

Treatment Duration

• Standard treatment: 3-5 days for prophylaxis of uncomplicated wounds 1
• Extended treatment required for:
  • Established infections: 7-10 days
  • Septic arthritis: 3-4 weeks
  • Osteomyelitis: 4-6 weeks 1, 3

Additional Management

• Wound care: Thorough cleaning with sterile normal saline and removal of superficial debris 1
• Tetanus prophylaxis: Administer tetanus toxoid if not vaccinated within 10 years (Tdap preferred if not previously given) 1
• Rabies consideration: Consult local health officials to determine if post-exposure prophylaxis is needed 1
• Wound closure: Primary closure not recommended except for facial wounds, which should receive copious irrigation, cautious debridement, and preemptive antibiotics 1, 5

Common Pitfalls to Avoid

• Inadequate antibiotic coverage: First-generation cephalosporins, penicillinase-resistant penicillins, macrolides, and clindamycin alone have poor activity against P. multocida and should be avoided 1
• Delayed treatment: Wounds presenting after 8-12 hours typically have established infection requiring more aggressive management 1, 6
• Insufficient wound care: Proper cleaning and debridement are as important as antibiotic therapy 6
• Overlooking high-risk patients: Immunocompromised, asplenic, or liver disease patients require special attention due to risk of severe infections like C. canimorsus bacteremia 1

Dog bites in children warrant particular attention as they represent a significant proportion of cases, with nearly half of all patients being 18 years or younger and over 20% being 5 years or younger 7.