Best Antibiotic for Animal Bites

Amoxicillin-clavulanate is the first-line antibiotic for animal bite wounds, both for prophylaxis and treatment. 1, 2, 3

First-Line Treatment

Oral therapy: Amoxicillin-clavulanate 875/125 mg twice daily is the antibiotic of choice for animal bites because it provides comprehensive coverage against the polymicrobial flora typical of these wounds, including Pasteurella species (found in ~50% of dog bites), staphylococci, streptococci, and anaerobes 1, 2, 3
The combination specifically addresses beta-lactamase-producing organisms that are commonly present in animal bite wounds 2, 4
This recommendation comes from the Infectious Diseases Society of America guidelines and is consistently supported across multiple high-quality sources 1, 2, 3

If the patient has a penicillin allergy, use one of these alternatives:

Doxycycline 100 mg twice daily is the preferred alternative, with excellent activity against Pasteurella multocida 2, 3
Moxifloxacin 400 mg daily can be used as monotherapy, providing coverage for both aerobic and anaerobic organisms 2
Fluoroquinolones (ciprofloxacin or levofloxacin) PLUS metronidazole for anaerobic coverage 1, 2

Avoid clindamycin as monotherapy for animal bites, as it lacks adequate coverage against Pasteurella species 2, 5

For patients requiring hospitalization or IV therapy:

Ampicillin-sulbactam 1, 2
Piperacillin-tazobactam 1, 2
Second- or third-generation cephalosporins (cefuroxime, cefoxitin, ceftriaxone, cefotaxime) 1, 2
Carbapenems (ertapenem, imipenem, meropenem) 1, 2

Do not use these antibiotics for animal bites:

First-generation cephalosporins (cefalexin) - inadequate coverage against Pasteurella 2
Penicillinase-resistant penicillins (dicloxacillin) - poor activity against bite wound pathogens 2
Macrolides (erythromycin) - insufficient coverage 2
Clindamycin alone - lacks Pasteurella coverage 2

Antibiotic prophylaxis is particularly important for:

Cat bites (higher infection risk due to deep puncture wounds) 6, 7
Hand wounds (highest risk of serious complications including septic arthritis and osteomyelitis) 2, 6, 7
Puncture wounds 6, 7
Wounds near bones or joints 2
Immunocompromised patients (especially those with asplenia or liver disease, who are at risk for fatal Capnocytophaga canimorsus sepsis) 2

Beyond antibiotics, proper wound care is essential:

Copious irrigation with normal saline or tap water is the most important intervention and can significantly reduce infection risk 2, 3
Do not close infected wounds 2
Facial wounds may be closed primarily if there is meticulous wound care, copious irrigation, and antibiotic prophylaxis 2
Tetanus prophylaxis if not vaccinated within the past 10 years (Tdap preferred over Td if not previously given) 2, 3

Watch for these warning signs requiring extended therapy:

Pain disproportionate to injury near bone or joint suggests periosteal penetration 2
Hand wounds are often more severe than they appear 2
Complications such as septic arthritis or osteomyelitis require 4-6 weeks of antibiotic therapy 2