What is the recommended dosage and duration of amoxicillin-clavulanate (Augmentin) for treating dog bites?

Amoxicillin-Clavulanate Dosing for Dog Bite Wounds

For dog bite infections, prescribe amoxicillin-clavulanate 875/125 mg twice daily for adults, with treatment duration of 3-5 days for prophylaxis in high-risk wounds or 7-10 days for established infections. 1, 2

Adult Dosing

• Standard dose: 875/125 mg orally twice daily 1, 2, 3
• Alternative dosing: 500/125 mg three times daily (though twice daily is preferred due to better compliance and less diarrhea) 3
• Administer at the start of meals to enhance clavulanate absorption and minimize gastrointestinal side effects 3

Pediatric Dosing

• For children ≥12 weeks (3 months): 45 mg/kg/day divided every 12 hours based on the amoxicillin component 2, 3
• For neonates and infants <12 weeks: 30 mg/kg/day divided every 12 hours 3
• Children weighing ≥40 kg should receive adult dosing 3
• The every 12-hour regimen is strongly preferred over every 8-hour dosing as it causes significantly less diarrhea 3

Treatment Duration Algorithm

Duration depends on clinical presentation and infection severity:

• 3-5 days for prophylactic/preemptive therapy in high-risk wounds presenting within 24 hours 1, 2
• 7-10 days for uncomplicated established infections 1
• 3-4 weeks for septic arthritis 1
• 4-6 weeks for osteomyelitis 1

High-Risk Wounds Requiring Prophylaxis (3-5 days)

Prophylactic antibiotics are indicated when patients present within 24 hours with any of the following features: 1, 2

• Hand, foot, face, genital, or near-joint locations 2, 4
• Deep wounds or puncture wounds (especially if bone, tendon sheath, or joint penetration suspected) 1, 2, 4
• Immunocompromised status, asplenia, advanced liver disease, or diabetes 1, 2
• Pre-existing or resultant edema of affected area 1, 2
• Moderate to severe injuries 2
• Presentation >9 hours after injury 2

Critical Timing Consideration

Do NOT prescribe prophylactic antibiotics if the patient presents ≥24 hours after the bite without signs of infection. 1 Prophylactic antibiotics are only beneficial when given early (within 24 hours) for fresh wounds at high risk of infection. 1 Prescribing antibiotics "just in case" at late presentation without infection violates guideline recommendations and promotes antimicrobial resistance. 1

Alternative Regimens for Penicillin Allergy

• Non-anaphylactic penicillin allergy: Doxycycline 100 mg twice daily (avoid in children <8 years) 2
• Severe penicillin allergy: Fluoroquinolone (such as moxifloxacin as monotherapy) plus metronidazole for adequate anaerobic coverage 1, 2

Common Pitfalls to Avoid

• Never use first-generation cephalosporins, macrolides, or penicillinase-resistant penicillins alone as they have poor activity against Pasteurella multocida, which is present in 50% of dog bite wounds 1, 2, 5
• Do not substitute two 250/125 mg tablets for one 500/125 mg tablet—they contain different amounts of clavulanic acid and are not equivalent 3
• Hand wounds often require longer treatment duration due to their serious nature and high infection risk 1, 5
• Consider Capnocytophaga canimorsus in asplenic patients or those with liver disease, as this pathogen can cause severe complications in these populations 1

Supporting Evidence

Amoxicillin-clavulanate is the first-line agent because dog bite wounds contain an average of 5 different bacterial species, including Pasteurella species (50%), Staphylococcus aureus (40%), Streptococcus species (40%), and various anaerobes. 1, 2 Meta-analysis demonstrates that prophylactic antibiotics reduce infection risk with a relative risk of 0.56, preventing one infection for every 14 patients treated. 6 Over 90% of both gram-negative and gram-positive isolates from dog bites are susceptible to amoxicillin-clavulanate. 7