What is the treatment for a mouse bite?

Treatment of Mouse Bites

Mouse bites should be immediately irrigated with copious amounts of sterile saline or running tap water, and antibiotic prophylaxis is generally not required unless the wound is deep, involves the hand, or the patient is immunocompromised. 1, 2

Immediate Wound Management

• Irrigate the wound thoroughly with running tap water or sterile saline until all visible debris is removed. 2 Running tap water is as effective as sterile saline and superior to antiseptic solutions like povidone-iodine. 2
• Remove only superficial debris; avoid aggressive debridement that causes additional tissue damage. 1
• Do not use iodine- or antibiotic-containing solutions for routine cleansing. 1

Wound Closure Decisions

• Leave most mouse bite wounds open to heal by secondary intention. 2
• Do not close infected wounds or wounds presenting more than 8 hours after injury. 1, 2
• For clean wounds seen early (<8 hours), consider approximation with Steri-Strips rather than sutures. 1
• Facial wounds are an exception and may be closed primarily after meticulous irrigation and prophylactic antibiotics. 1, 2

Antibiotic Therapy

Antibiotic prophylaxis is generally NOT required for mouse bites because rodents (including mice) are almost never infected with rabies and have not been known to cause rabies in humans in the United States. 3 However, consider antibiotics in specific high-risk situations:

Indications for Antibiotic Prophylaxis:

• Hand wounds or wounds near joints/bones 1
• Deep puncture wounds 2
• Wounds presenting more than 8 hours after injury 2
• Immunocompromised patients 2
• Wounds with crush injury or devitalized tissue 2

Antibiotic Selection:

• First-line oral therapy: Amoxicillin-clavulanate 1, 2
• Alternative oral options for penicillin-allergic patients: Doxycycline, penicillin VK plus dicloxacillin, or fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) plus metronidazole or clindamycin 4, 1
• Intravenous therapy for severe infections: Ampicillin-sulbactam, piperacillin-tazobactam, second-generation cephalosporins (cefoxitin), or carbapenems (ertapenem, imipenem, meropenem) 4, 1

Duration of Treatment:

• Standard wound infections: 7-10 days 1
• Septic arthritis: 3-4 weeks 1
• Osteomyelitis: 4-6 weeks 1

Tetanus Prophylaxis

• Administer tetanus toxoid 0.5 mL intramuscularly if vaccination status is outdated or unknown. 1, 2
• For dirty wounds, give a booster if more than 5 years since the last dose. 1
• For clean wounds, give a booster if more than 10 years since the last dose. 1

Rabies Prophylaxis

Rabies prophylaxis is NOT required for mouse bites in the United States. 3, 1 Rodents (including mice, rats, squirrels, hamsters, guinea pigs, gerbils, and chipmunks) are almost never found to be infected with rabies and have not been known to cause rabies among humans in the United States. 3 However, consult your local health department for regional risk assessment if the bite occurred in an unusual circumstance or high-prevalence area. 1

Follow-Up and Monitoring

• Elevate the injured extremity to reduce swelling and accelerate healing. 1, 2
• Follow up within 24 hours by phone or office visit for all outpatients. 1, 2
• Signs requiring immediate re-evaluation include redness, swelling, foul-smelling drainage, increased pain, or fever. 2
• Consider hospitalization if infection progresses despite appropriate antimicrobial therapy, deep tissue involvement is suspected, or the patient is immunocompromised. 1

Critical Pitfalls to Avoid

• Do not use antiseptic solutions for irrigation—they offer no benefit over water or saline. 2
• Do not close wounds more than 8 hours old or contaminated wounds. 1, 2
• Do not use antibiotics with poor coverage for typical wound pathogens if antibiotics are indicated (avoid first-generation cephalosporins, macrolides, or clindamycin monotherapy). 2
• Do not routinely prescribe antibiotics for all mouse bites—reserve for high-risk wounds only. 3, 1

Special Consideration: Lymphocytic Choriomeningitis Virus

While extremely rare, mouse bites can theoretically transmit lymphocytic choriomeningitis virus (LCMV), which can cause viral meningitis. 5 This infection is self-limiting in immunocompetent patients and typically occurs in autumn and winter when mice retreat into houses. 5 If a patient develops severe progressive headache, nausea, and vomiting weeks after a mouse bite, consider LCMV and perform cerebrospinal fluid analysis. 5