What antibiotics are recommended for dog bite management?

Dog Bite Management and Antibiotics

First-Line Antibiotic Recommendation

Amoxicillin-clavulanate 875/125 mg twice daily is the first-line antibiotic for dog bite management when antibiotics are indicated. 1, 2, 3

This agent provides comprehensive coverage against the polymicrobial flora characteristic of dog bites, including Pasteurella species (present in 50% of dog bites), Staphylococcus aureus (40%), Streptococcus species (40%), and anaerobes such as Bacteroides, Fusobacterium, Porphyromonas, and Prevotella species. 1, 3

When to Prescribe Antibiotics: Risk Stratification Algorithm

High-Risk Wounds Requiring Prophylactic Antibiotics (3-5 days):

Wound location criteria: 1, 2

• Hand, foot, face, or genital wounds
• Wounds near joints or that may have penetrated periosteum or joint capsule

Wound characteristics: 2, 3

• Deep wounds
• Puncture wounds
• Wounds with significant tissue damage or crush injury

Patient risk factors: 1, 2, 3

• Immunocompromised status
• Diabetes mellitus
• Advanced liver disease
• Asplenia (particularly concerning for Capnocytophaga canimorsus sepsis)
• Prosthetic joints or heart valves
• Pre-existing or resultant edema of the affected area

Critical Timing Consideration:

Antibiotics should NOT be prescribed if the patient presents ≥24 hours after the bite without signs of infection. 2, 3 Prophylactic antibiotics are only beneficial when given early (within 24 hours) for fresh wounds at high risk. 3 This represents a key guideline recommendation from the World Society of Emergency Surgery that prevents unnecessary antibiotic use and resistance. 1, 2

Alternative Antibiotic Options

When amoxicillin-clavulanate is contraindicated:

Oral alternatives: 1, 2, 3

• Doxycycline 100 mg twice daily (excellent activity against Pasteurella multocida)
• Moxifloxacin as monotherapy
• Clindamycin plus a fluoroquinolone (ciprofloxacin 500-750 mg twice daily or levofloxacin 500 mg daily)

Intravenous options for severe infections: 1, 3

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours
• Piperacillin-tazobactam 3.37 g every 6-8 hours
• Carbapenems (ertapenem 1 g daily, imipenem 1 g every 6-8 hours, or meropenem 1 g every 8 hours)
• Ceftriaxone 1-2 g every 12-24 hours plus metronidazole 500 mg every 8 hours

Treatment Duration

Prophylaxis for high-risk wounds: 3-5 days 1, 2, 3

Established uncomplicated infections: 7-10 days 2, 3

Septic arthritis: 3-4 weeks 2, 3

Osteomyelitis: 4-6 weeks 2, 3

Critical Pitfalls to Avoid

Never use these agents alone for dog bites: 3

• First-generation cephalosporins (cephalexin, cefazolin)
• Macrolides (azithromycin, clarithromycin)
• Penicillinase-resistant penicillins (dicloxacillin, nafcillin)

These agents have poor activity against Pasteurella multocida, which is present in 50% of dog bite wounds. 3 While older literature from 1980-1988 suggested these agents, current guidelines based on microbiologic data clearly contraindicate their use as monotherapy. 4, 5

Do not prescribe antibiotics "just in case" for late presentations (≥24 hours) without infection signs. 2, 3 This violates current guideline recommendations and promotes antimicrobial resistance.

Special Population Considerations

Asplenic patients or those with advanced liver disease: 1, 3 These patients require immediate aggressive antibiotic therapy due to risk of severe sepsis from Capnocytophaga canimorsus, which can cause fulminant sepsis with high mortality.

Pediatric dosing (≥12 weeks old): 6

• 45 mg/kg/day divided every 12 hours for moderate-severe infections
• 25 mg/kg/day divided every 12 hours for less severe infections
• Maximum dose: adult dosing for children ≥40 kg

Additional Essential Management

Tetanus prophylaxis: Required if vaccination not current within 10 years; Tdap preferred over Td if not previously given. 1

Rabies prophylaxis: Consultation with local health officials recommended to determine need for postexposure prophylaxis (immune globulin plus vaccination on days 0,3,7, and 14). 1, 7

Wound management: 1, 3

• Thorough irrigation with sterile normal saline (avoid high-pressure irrigation which spreads bacteria deeper)
• Debridement of necrotic tissue
• Exploration for foreign bodies and assessment of tendon, bone, or joint involvement
• Primary closure generally avoided except for facial wounds (which should receive copious irrigation, cautious debridement, and preemptive antibiotics)

Context: Infection Rates

Dog bites have a relatively low infection rate of 5-25%, compared to 30-50% for cat bites and 20-25% for human bites. 1, 3 This lower rate supports the selective rather than universal use of prophylactic antibiotics based on risk stratification.