What is the best antibiotic for a dog bite?

Best Antibiotic for Dog Bite

Amoxicillin-clavulanate is the first-line antibiotic for dog bite wounds, both for prophylaxis and treatment of established infection. 1, 2

First-Line Treatment

• Amoxicillin-clavulanate 875/125 mg twice daily orally is the antibiotic of choice for dog bites 1, 2
• This combination effectively covers the polymicrobial flora typical of dog bites, including Pasteurella multocida (present in ~50% of cases), staphylococci, streptococci, and anaerobes 2, 3
• The clavulanate component is critical because it addresses beta-lactamase-producing organisms commonly found in animal bite wounds 2

Alternative Options for Penicillin Allergy

If the patient has a penicillin allergy, use one of these alternatives:

• Doxycycline 100 mg twice daily is an excellent single-agent alternative with strong activity against Pasteurella multocida 1, 2
• Moxifloxacin 400 mg daily can be used as monotherapy, providing coverage of both aerobic and anaerobic organisms 2, 4
• Fluoroquinolone (ciprofloxacin or levofloxacin) plus metronidazole for combined aerobic and anaerobic coverage 2

Intravenous Options for Severe Infections

For hospitalized patients or severe infections requiring IV therapy:

• Ampicillin-sulbactam 1.5–3.0 g every 6–8 hours 1, 2
• Piperacillin-tazobactam 3.37 g every 6–8 hours 1, 2
• Carbapenems (ertapenem, imipenem, or meropenem) 1, 2

Antibiotics to AVOID

Do not use these antibiotics as they provide inadequate coverage:

• First-generation cephalosporins (e.g., cephalexin) - poor Pasteurella coverage 2
• Penicillinase-resistant penicillins (e.g., dicloxacillin) - inadequate anaerobic coverage 2
• Macrolides (e.g., erythromycin) - poor coverage of bite wound flora 2
• Clindamycin as monotherapy - misses key pathogens 2

Indications for Prophylactic Antibiotics (3–5 Days)

Preemptive antibiotic therapy is recommended for high-risk wounds 1:

• Immunocompromised or asplenic patients 1
• Advanced liver disease (risk of fatal Capnocytophaga canimorsus sepsis) 1, 2
• Moderate to severe injuries, especially to the hand or face 1, 5
• Puncture wounds, particularly if bone, tendon sheath, or joint penetration is suspected 1, 5
• Wounds with preexisting or resultant edema 1
• Wounds requiring primary closure 5

Critical Wound Management Principles

Beyond antibiotics, proper wound care is equally important 2, 6:

• Copious irrigation with normal saline is essential and may reduce infection risk more than antibiotics alone 2, 6
• Infected wounds should not be closed primarily 2
• Facial wounds may be closed primarily if meticulously cleaned, copiously irrigated, and prophylactic antibiotics are given 2, 4
• Update tetanus prophylaxis if not current within 10 years 2, 5
• Assess need for rabies postexposure prophylaxis with local health officials 1, 6

High-Risk Complications to Monitor

Watch for these serious complications that require prolonged therapy 2:

• Hand wounds are particularly prone to severe complications including septic arthritis and osteomyelitis 2
• Pain disproportionate to injury near bone or joint suggests periosteal penetration 2
• Osteomyelitis requires 4–6 weeks of antibiotic therapy 2
• Capnocytophaga canimorsus can cause fatal sepsis in asplenic or cirrhotic patients 2

Note: The IDSA guidelines 1 and current evidence 2 strongly converge on amoxicillin-clavulanate as the standard of care, with the caveat that MRSA is not covered by any of these regimens—though MRSA is not a typical dog bite pathogen.