What is the best initial treatment for a rat bite?

Rat Bite Initial Treatment

For rat bites, immediately irrigate the wound with copious amounts of water or saline, provide tetanus prophylaxis if needed, and use good wound care without routine prophylactic antibiotics unless the wound is high-risk (deep puncture, hand location, or signs of infection). 1, 2

Immediate Wound Management

• Irrigate the wound thoroughly with large volumes of warm or room temperature potable water or sterile saline to remove debris and reduce bacterial load 1
• Clean the wound with sterile normal saline; avoid iodine or antibiotic-containing solutions during initial cleaning 3
• Do not close the wound if any signs of infection are present 3
• For clean, non-infected wounds seen within 8 hours, consider approximation with Steri-Strips rather than sutures 3
• Facial wounds are an exception and may be closed primarily after meticulous irrigation and with prophylactic antibiotics 3

Antibiotic Decision-Making

The evidence on prophylactic antibiotics for rat bites is notably divergent, requiring clinical judgment:

Against routine prophylaxis:

• A prospective study of 50 uninfected rat bite wounds showed only 2% developed infection without prophylactic antibiotics, suggesting a low natural infection rate 2
• Most rat bites are superficial (Type I scratches) and do not require hospital admission or antibiotics 4

For selective prophylaxis:

• Deep puncture wounds from rodent bites should be considered high-risk for infection given their penetrating nature 5
• Hand wounds, puncture wounds, and "dirty" wounds warrant antibiotic prophylaxis 6
• Polymicrobial infections (72.5% of infected rat bite wounds) include both aerobic and anaerobic bacteria, with Staphylococcus aureus being most common 5

When antibiotics are indicated, use:

• First-line oral therapy: Amoxicillin-clavulanate for broad-spectrum coverage including anaerobes 3
• Alternative for penicillin allergy: Doxycycline, or a fluoroquinolone (ciprofloxacin, levofloxacin, moxifloxacin) plus metronidazole or clindamycin 3
• If infection develops after initial presentation: Cephalosporin or penicillinase-resistant penicillin with appropriate surgical wound care 2

Tetanus and Rabies Prophylaxis

• Tetanus prophylaxis is mandatory - administer 0.5 mL tetanus toxoid intramuscularly if status is outdated or unknown 3, 2
• Rabies prophylaxis is usually not required for rat bites, as rabies transmission from rats is extraordinarily rare in the United States 3
• Consider rabies prophylaxis only in exceptional circumstances where the rat has suspected rabies exposure or compatible clinical signs 3

Wound Classification and Treatment Algorithm

Based on wound severity 4:

• Type I (superficial scratches): Conservative wound care only, no antibiotics needed
• Type II (deeper bites with infection/ulceration): May require drainage and debridement if infected; consider antibiotics
• Type III (full-thickness tissue loss): Requires surgical intervention including possible skin grafting; antibiotics indicated

Follow-Up and Monitoring

• Elevate the injured body part if swollen to accelerate healing 3
• Follow up within 24 hours by phone or office visit for outpatients 3
• Watch for signs of infection including cellulitis, lymphangitis, or systemic symptoms 7
• Most patients recover without complications when wounds receive appropriate initial care 4

Common Pitfalls to Avoid

• Do not routinely prescribe antibiotics for all rat bites - reserve for high-risk wounds 2
• Do not close infected wounds or wounds presenting late 3
• Do not neglect tetanus status - this is frequently deficient in rat bite patients 2
• Do not overlook hand wounds, which require more aggressive management 6