What are the recommended antibiotics and rabies vaccine (post-exposure prophylaxis) for a dog bite?

Dog Bite Management: Antibiotics and Rabies Post-Exposure Prophylaxis

For dog bites, use amoxicillin-clavulanate 875/125 mg twice daily for 3-5 days as first-line antibiotic prophylaxis, and initiate rabies post-exposure prophylaxis with both rabies immune globulin (RIG) and a 5-dose vaccine series (days 0,3,7,14,28) if the dog's rabies status cannot be confirmed through 10-day observation. 1

Immediate Wound Management

All dog bite wounds require immediate thorough cleansing with soap and water for 15 minutes, followed by irrigation with povidone-iodine solution. 1, 2 This is the single most important intervention for preventing both bacterial infection and rabies transmission. 1

• Use copious irrigation with normal saline via a 20-mL or larger syringe or 20-gauge catheter 3
• Explore wounds for tendon, bone, or joint capsule involvement and foreign bodies 1, 3
• Avoid suturing when possible; primary closure should be limited to cosmetically important areas like the face 1

Antibiotic Prophylaxis Decision Algorithm

Preemptive antibiotics for 3-5 days are strongly recommended for patients with: 1

• High-risk wounds: Moderate to severe injuries, puncture wounds, hand or face involvement, or wounds penetrating periosteum/joint capsule 1, 4
• High-risk hosts: Immunocompromised, asplenic, advanced liver disease, or preexisting edema of affected area 1
• Wounds requiring primary closure 4

First-Line Antibiotic Choice

Amoxicillin-clavulanate 875/125 mg orally twice daily is the first-line agent because it provides coverage against both aerobic bacteria (including Pasteurella multocida, present in 20-30% of dog bites) and anaerobes. 1, 3, 5, 4

Alternative regimens for penicillin-allergic patients: 1

• Doxycycline 100 mg twice daily (excellent against P. multocida but some streptococci resistant)
• Moxifloxacin 400 mg daily (provides anaerobic coverage as monotherapy)
• Combination therapy: Trimethoprim-sulfamethoxazole 160-800 mg twice daily PLUS metronidazole 250-500 mg three times daily

Common pitfall: Clindamycin alone misses P. multocida, and fluoroquinolones other than moxifloxacin require anaerobic coverage. 1

Rabies Post-Exposure Prophylaxis Decision Algorithm

Step 1: Determine Need for Observation vs. Immediate PEP

If the dog is available and appears healthy, observe for 10 days before initiating PEP. 2 If the dog develops signs of rabies during observation or cannot be observed, proceed immediately with PEP. 2

Factors indicating higher rabies risk requiring immediate consideration of PEP: 2

• Unprovoked attack (vs. provoked attacks during feeding/handling)
• Dog showing abnormal behavior or signs of illness
• Dog has unexplained wounds suggesting wildlife exposure
• Geographic area with endemic rabies (US-Mexico border, areas with wildlife rabies)
• Unvaccinated or unknown vaccination status dog

Step 2: Rabies PEP Protocol for Previously Unvaccinated Persons

The complete regimen consists of: 1, 2

1. Rabies immune globulin (RIG) 20 IU/kg body weight - ONCE on day 0 only 1

   • Infiltrate full dose around and into wounds if anatomically feasible
   • Inject remaining volume intramuscularly at site distant from vaccine
   • Can be given up to day 7 if not given initially, but NOT beyond day 7 1
   • Never administer in same syringe or anatomical site as first vaccine dose 1

2. Rabies vaccine series: 5 doses of 1 mL each on days 0,3,7,14, and 28 1, 2

   • Administer intramuscularly in deltoid (adults) or anterolateral thigh (children)
   • Either HDCV or PCECV can be used 1

Note: A 4-dose schedule (days 0,3,7,14) is now accepted as adequate for immunocompetent persons, though the traditional 5-dose regimen remains standard. 6

Step 3: Previously Vaccinated Persons

Persons with documented prior complete rabies vaccination receive vaccine ONLY (no RIG) - typically 2 doses on days 0 and 3. 1

Critical Pitfalls to Avoid

• Delaying wound cleansing - this is the most effective single intervention 2
• Failing to observe healthy domestic dogs for 10 days before initiating unnecessary PEP 2
• Exceeding recommended RIG dose - can suppress active antibody production 1
• Administering RIG after day 7 - contraindicated as endogenous antibody response has begun 1
• Assuming vaccinated dogs cannot be rabid - even vaccinated animals occasionally develop rabies 2

Additional Considerations

• Tetanus prophylaxis should be updated as indicated 1, 3
• Consult local health officials regarding rabies risk assessment and reporting requirements 1
• Geographic considerations: Dogs remain the major rabies source in most of Asia, Africa, and Latin America, representing increased risk for travelers 2