What empiric antibiotics are recommended for a dog bite?

Empiric Antibiotics for Dog Bite

Amoxicillin-clavulanate 875/125 mg twice daily is the first-line empiric antibiotic for dog bite wounds. 1

First-Line Treatment

• Amoxicillin-clavulanate is the oral antibiotic of choice for empiric treatment of dog bites, providing comprehensive coverage against the polymicrobial flora typical of these wounds 1
• The standard adult dose is 875/125 mg twice daily or 500/125 mg three times daily, taken at the start of meals to enhance absorption and minimize gastrointestinal side effects 2
• This combination effectively covers Pasteurella multocida (present in ~50% of dog bites), staphylococci, streptococci, and anaerobes 1
• The clavulanate component is critical for addressing beta-lactamase-producing organisms commonly found in animal bite wounds 1

Alternative Regimens for Penicillin Allergy

If the patient has a penicillin allergy, choose from these options:

• Doxycycline 100 mg twice daily - excellent activity against P. multocida and provides good coverage, though some streptococci may be resistant 1
• Moxifloxacin 400 mg daily - can be used as monotherapy with good coverage of both aerobes and anaerobes 1
• Levofloxacin 750 mg daily OR ciprofloxacin 500-750 mg twice daily PLUS metronidazole 500 mg three times daily - the fluoroquinolone covers P. multocida but requires metronidazole for anaerobic coverage 1

Intravenous Options for Severe Infections

For hospitalized patients or severe infections requiring IV therapy:

• Ampicillin-sulbactam 1.5-3.0 g every 6 hours 1
• Piperacillin-tazobactam 3.37 g every 6-8 hours 1
• Ertapenem 1 g daily or other carbapenems 1
• Cefoxitin 1 g every 6-8 hours (second-generation cephalosporin) 1

Note: All IV options miss MRSA coverage; add vancomycin if MRSA is suspected 1

Critical Antibiotics to AVOID

Do not use these antibiotics for dog bites as they lack adequate coverage against P. multocida:

• First-generation cephalosporins (cephalexin, cefazolin, cefadroxil) - consistently ineffective against P. multocida 1, 3
• Clindamycin monotherapy - misses P. multocida despite good activity against staphylococci, streptococci, and anaerobes 1
• Dicloxacillin or oxacillin alone - inadequate P. multocida coverage 1, 3
• Macrolides (erythromycin) - poor activity against P. multocida 1, 3

Essential Wound Management Considerations

Beyond antibiotics, proper wound care is critical:

• Copious irrigation is essential and may significantly reduce infection risk 1
• Do not close infected wounds - this is a fundamental principle 1
• Facial wounds are an exception and may be closed primarily with meticulous wound care, copious irrigation, and preemptive antibiotics 1
• Tetanus prophylaxis should be administered if vaccination is not current within 10 years (Tdap preferred over Td if not previously given) 1

High-Risk Scenarios Requiring Special Attention

• Hand wounds are often more severe than wounds on fleshy body parts and warrant closer monitoring 1
• Pain disproportionate to injury near bone or joint suggests possible periosteal penetration, osteomyelitis, or septic arthritis 1
• Patients with asplenia or liver disease are at higher risk for Capnocytophaga canimorsus bacteremia and sepsis 1
• Complications such as osteomyelitis or septic arthritis require prolonged therapy (4-6 weeks) 1

Clinical Evidence Supporting Amoxicillin-Clavulanate

The recommendation for amoxicillin-clavulanate is supported by both guideline consensus and clinical research demonstrating its effectiveness as monotherapy for moderate dog bite wounds, with over 90% of both gram-negative and gram-positive isolates showing susceptibility 4, 5