What antibiotic treatment is recommended for a dog scratch?

Dog Scratch Antibiotic Treatment

For dog scratches, amoxicillin-clavulanate 875/125 mg twice daily is the first-line antibiotic for both prophylaxis and treatment of infection. 1, 2

When to Prescribe Antibiotics

Preemptive antibiotic therapy for 3-5 days is recommended for dog scratches if the patient has any of the following high-risk features: 1

• Immunocompromised status (including asplenia or advanced liver disease) 1
• Moderate to severe injuries, especially to the hand or face 1
• Preexisting or resultant edema of the affected area 1
• Deep wounds that may have penetrated the periosteum or joint capsule 1

For low-risk superficial scratches in immunocompetent patients not involving high-risk anatomic sites, prophylactic antibiotics provide marginal benefit and may be omitted with close observation. 1

First-Line Antibiotic Choice

Amoxicillin-clavulanate is the preferred agent because it provides coverage against both aerobic and anaerobic bacteria commonly found in dog scratches, including Pasteurella multocida, staphylococci, streptococci, and anaerobes. 1, 2, 3

• Dosing: 875/125 mg orally twice daily for adults 1, 2
• Duration: 3-5 days for prophylaxis; 7-10 days for established infection 4, 2

Alternative Regimens for Penicillin Allergy

If the patient has a penicillin allergy, consider these alternatives: 1, 2

• Doxycycline 100 mg twice daily - excellent activity against P. multocida, though some streptococci may be resistant 1, 2
• Fluoroquinolones (ciprofloxacin 500-750 mg twice daily, levofloxacin 750 mg daily, or moxifloxacin 400 mg daily) - good Pasteurella coverage but misses MRSA and some anaerobes 1, 2
• Combination therapy: TMP-SMX 160-800 mg twice daily plus metronidazole 250-500 mg three times daily for combined aerobic/anaerobic coverage 1, 2

Antibiotics to Avoid

Do not use first-generation cephalosporins (cephalexin) or penicillinase-resistant penicillins (dicloxacillin) as monotherapy - these agents miss P. multocida and anaerobes, which are critical pathogens in dog scratches. 4, 2

Special Considerations

Hand Injuries

Hand scratches have the highest infection risk and complication rate, including tendosynovitis, septic arthritis, and osteomyelitis, requiring prompt antibiotic therapy and close follow-up. 4, 2

Severe Infections Requiring IV Therapy

For patients with systemic signs (fever, lymphangitis, significant cellulitis), hospitalization with IV antibiotics is indicated: 4

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours IV (first-line) 1, 4
• Piperacillin-tazobactam 3.37 g every 6-8 hours IV (alternative) 1, 4
• Transition to oral amoxicillin-clavulanate after 3-5 days of IV therapy to complete 7-10 days total 4

Additional Wound Management

• Thoroughly cleanse the wound with sterile normal saline 2
• Evaluate tetanus immunization status and update if needed 2
• Assess rabies risk for scratches from unknown or stray dogs; consult local health officials 1, 2
• Elevate the injured body part if swollen to accelerate healing 2

Follow-Up and Red Flags

Patients should return immediately if signs of infection develop, including: 2

• Increasing pain, redness, or swelling
• Purulent drainage
• Fever
• Red streaking (lymphangitis)

Monitor closely for complications such as septic arthritis, osteomyelitis, or tendonitis, particularly with hand wounds. 2