Best Antibiotic for Dog Bite
Amoxicillin-clavulanate 875/125 mg twice daily is the first-line oral antibiotic for dog bites in adults with normal renal function and no penicillin allergy. 1, 2
Why Amoxicillin-Clavulanate is First-Line
Amoxicillin-clavulanate provides comprehensive coverage against the polymicrobial flora found in dog bite wounds, including Pasteurella multocida, Staphylococcus aureus, streptococci, and anaerobic organisms—all commonly isolated from these injuries. 1, 2
Dog bite wounds contain an average of 5 different bacterial species, with 60% yielding mixed aerobic and anaerobic organisms, making broad-spectrum coverage essential. 2
Both the Infectious Diseases Society of America and the American College of Physicians strongly recommend amoxicillin-clavulanate as first-line therapy based on its activity against the most prevalent pathogens. 1, 2
Dosing and Duration
Standard dose: Amoxicillin-clavulanate 875/125 mg orally twice daily for 3-5 days for prophylaxis or 7-10 days for established infection. 2
For pediatric patients, the dose is 45 mg/kg/day divided every 12 hours. 1
Alternative Regimens for Penicillin Allergy
For non-anaphylactic penicillin allergy: Doxycycline 100 mg twice daily provides excellent activity against Pasteurella multocida and can be used as monotherapy. 1, 2
For severe penicillin allergy: Use combination therapy with doxycycline 100 mg twice daily PLUS a fluoroquinolone (moxifloxacin 400 mg daily, levofloxacin 500-750 mg daily, or ciprofloxacin 500-750 mg twice daily) PLUS clindamycin 300 mg three times daily. 2
An alternative for severe allergy is trimethoprim-sulfamethoxazole 160-800 mg twice daily PLUS clindamycin 300 mg three times daily. 2
Critical Pitfalls to Avoid
Never use monotherapy with first-generation cephalosporins, macrolides, or penicillinase-resistant penicillins alone—these agents have poor or no activity against Pasteurella multocida, which is present in the majority of dog bite infections. 2
Hand puncture wounds carry exceptionally high risk for deep structure involvement (tendons, joints, bone) and may progress to septic arthritis or osteomyelitis if not promptly managed. 1
High-Risk Patients Requiring Special Consideration
Asplenic patients, those with advanced liver disease, or immunocompromised individuals are at risk for fulminant sepsis from Capnocytophaga canimorsus and require aggressive management with immediate antibiotic therapy. 2, 3
These high-risk patients should receive amoxicillin-clavulanate prophylaxis for all dog bites, even minor ones. 4
When to Escalate to IV Therapy
Initiate IV therapy with ampicillin-sulbactam 1.5-3.0 g every 6-8 hours, piperacillin-tazobactam 3.37 g every 6-8 hours, or ertapenem 1 g daily for patients with systemic symptoms, moderate-to-severe infection, or high-risk wounds (hand, foot, face, genital location). 2
Transition to oral therapy after 3-5 days of IV treatment once clinical improvement is evident. 2
Essential Adjunctive Management
Thoroughly cleanse wounds with copious sterile normal saline irrigation and debride any necrotic tissue. 2, 5
Assess for tendon, bone, or joint involvement by confirming full finger flexion and extension, intact sensation, and absence of joint tenderness—any abnormality warrants immediate hand surgery consultation. 1
Administer tetanus prophylaxis if not vaccinated within the past 10 years (Tdap preferred if not previously given). 1, 2
Consult local health officials regarding rabies post-exposure prophylaxis based on the animal's vaccination status and behavior. 1, 2
Wound Closure Considerations
Avoid primary closure for most dog bite wounds except facial wounds, which may be closed after thorough irrigation due to cosmetic concerns and excellent blood supply. 1
Instruct patients to watch for infection signs: redness extending >1-2 cm from wound edge, purulent drainage, fever >38°C, or worsening pain after 48 hours. 1
Elevate affected extremities above heart level for 48-72 hours to reduce edema and lower infection risk. 1