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 species (present in
50% of cases), staphylococci and streptococci (40%), and anaerobes 2, 3 - The clavulanate component specifically addresses beta-lactamase-producing organisms commonly found in animal bite wounds 2, 4
When to Initiate Antibiotics
Preemptive antibiotic therapy for 3-5 days is recommended for patients with: 1
- Immunocompromised status or asplenia
- Advanced liver disease (risk of fatal Capnocytophaga canimorsus sepsis) 2, 5
- Preexisting or resultant edema of the affected area
- Moderate to severe injuries, especially to the hand or face
- Injuries that may have penetrated the periosteum or joint capsule
- Puncture wounds 6
Important caveat: Low-risk wounds (superficial, not involving hand/face/foot, in immunocompetent patients presenting within 12-24 hours) may not require prophylactic antibiotics, though the evidence is mixed 1
Alternative Regimens for Penicillin Allergy
For patients allergic to penicillin: 1, 2
- Doxycycline 100 mg twice daily - excellent activity against Pasteurella multocida, though some streptococci may be resistant 1, 2
- Moxifloxacin 400 mg daily - provides both aerobic and anaerobic coverage as monotherapy 2
- Fluoroquinolone (ciprofloxacin or levofloxacin) plus metronidazole for combined aerobic and anaerobic coverage 2
Intravenous Options for Severe Infections
When IV therapy is required: 1, 2
- Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1
- Piperacillin-tazobactam 3.37 g every 6-8 hours 1
- Carbapenems (ertapenem, imipenem, or meropenem) 1, 2
- Cefoxitin (second-generation cephalosporin) 2
Antibiotics to AVOID
Do not use the following as monotherapy for dog bites: 2
- First-generation cephalosporins (e.g., cephalexin) - inadequate Pasteurella coverage
- Penicillinase-resistant penicillins (e.g., dicloxacillin) - miss anaerobes and Pasteurella
- Macrolides (e.g., erythromycin) - poor coverage
- Clindamycin alone - misses key pathogens
Critical Wound Management Principles
Beyond antibiotics, proper wound care is equally or more important: 1, 7
- Copious irrigation and thorough cleansing are essential and significantly reduce infection risk 2, 3
- Do not close infected wounds 2
- Facial wounds may be closed primarily if meticulous wound care, copious irrigation, and prophylactic antibiotics are provided 2, 7
- Update tetanus prophylaxis if not current within 10 years 2, 6
- Assess rabies risk and consult local health officials 1
Red Flags for Serious Complications
Watch for these complications requiring prolonged therapy (4-6 weeks): 2
- Hand wounds are particularly high-risk and often more severe 2
- Pain disproportionate to injury near bone or joint suggests periosteal penetration 2
- Septic arthritis, osteomyelitis, subcutaneous abscess formation, or tendinitis 2
- Bacteremia, especially with Capnocytophaga canimorsus in asplenic or liver disease patients 2, 5
Note: All beta-lactam/beta-lactamase inhibitor combinations miss MRSA, so if MRSA is suspected based on local epidemiology or patient risk factors, additional coverage is needed 1