What is the best oral antibiotic for a dog bite?

Best Oral Antibiotic for Dog Bite

Amoxicillin-clavulanate is the first-line oral antibiotic for dog bite treatment and prophylaxis. 1, 2

Primary Recommendation

• Amoxicillin-clavulanate (Augmentin) is the definitive oral antibiotic of choice for empiric treatment of dog bites, recommended by the Infectious Diseases Society of America and consistently supported across all major guidelines 1, 2
• The combination effectively covers the polymicrobial nature of dog bite wounds, including beta-lactamase producing organisms that are commonly present 2
• Dog bite wounds contain an average of 5 different bacterial isolates, with Pasteurella species in approximately 50% of cases, and staphylococci/streptococci in 40% 2, 3

Alternative Options for Penicillin Allergy

If the patient has a penicillin allergy, the following alternatives are recommended in order of preference:

• Doxycycline 100 mg twice daily is the best alternative, with excellent activity against Pasteurella multocida 2
• Moxifloxacin 400 mg daily can be used as monotherapy, providing coverage for both aerobic and anaerobic organisms 1, 2
• Fluoroquinolones (ciprofloxacin or levofloxacin) PLUS metronidazole for anaerobic coverage 1, 2

Antibiotics to Avoid

The following antibiotics have inadequate coverage and should NOT be used for dog bites:

• First-generation cephalosporins (cefalexin) - insufficient coverage for Pasteurella and anaerobes 2
• Penicillinase-resistant penicillins (dicloxacillin) - poor activity against Pasteurella 2
• Macrolides (erythromycin) - inadequate spectrum 2
• Clindamycin as monotherapy - does not cover all necessary pathogens 2

Indications for Antibiotic Prophylaxis

Antibiotics are indicated when any of the following are present:

• Puncture wounds, especially those penetrating bone, tendon sheath, or joint 4
• Bites to the hands or feet (hand wounds carry particularly high infection risk) 2, 5
• Facial or genital area bites 4
• Moderate to severe bite wounds 4
• Wounds requiring primary closure 4
• Immunocompromised or asplenic patients 4

Critical Wound Management Steps

Beyond antibiotics, proper wound care is essential:

• Copious irrigation with normal saline using a 20-mL or larger syringe is critical and can significantly reduce infection risk 2, 5
• Explore wounds for tendon, bone involvement, and foreign bodies 5
• Infected wounds should NOT be closed 2
• Facial wounds may be closed primarily only with meticulous care, copious irrigation, and antibiotic prophylaxis 2
• Update tetanus prophylaxis if not current within 10 years 2

High-Risk Complications to Monitor

• Capnocytophaga canimorsus can cause fatal bacteremia and sepsis, particularly in asplenic or cirrhotic patients 2
• Hand wounds are more severe than wounds to fleshy body parts 2
• Pain disproportionate to injury near bone or joint suggests periosteal penetration and requires aggressive evaluation 2
• Complications include septic arthritis, osteomyelitis, subcutaneous abscesses, and tendinitis, which may require 4-6 weeks of therapy 2

Common Pitfall

Pasteurella multocida is isolated in 20-30% of dog bites and over 50% of cat bites, and can cause serious infection with severe complications 6. This organism is resistant to many commonly prescribed antibiotics, which is why amoxicillin-clavulanate's broad spectrum is essential 2, 6.