How to treat a dog bite with signs of infection?

Treatment of Dog Bite with Signs of Infection

For a dog bite with signs of infection, amoxicillin-clavulanate is the first-line antimicrobial treatment due to its activity against both aerobic and anaerobic bacteria commonly found in these wounds. 1

Initial Assessment and Management

• Thoroughly cleanse the wound with sterile normal saline and remove superficial debris 1
• Copiously irrigate using a 20-mL or larger syringe or a 20-gauge catheter 2
• Explore the wound for tendon or bone involvement and possible foreign bodies 2
• Do not close infected wounds; they should be left open to heal by secondary intention 1
• Elevate the affected body part, especially if swollen, to accelerate healing 1

Antimicrobial Therapy

First-line Treatment:

• Oral therapy: Amoxicillin-clavulanate 875/125 mg twice daily 1
• Intravenous options (for severe infections):
  • Ampicillin-sulbactam (1.5–3.0 g every 6–8 h) 1
  • Piperacillin-tazobactam (3.37 g every 6–8 h) 1
  • Second-generation cephalosporins such as cefoxitin 1

Alternative Options (for penicillin-allergic patients):

• Doxycycline 100 mg twice daily (excellent activity against Pasteurella multocida) 1
• Fluoroquinolones (e.g., moxifloxacin 400 mg daily) plus metronidazole for anaerobic coverage 1
• Clindamycin plus trimethoprim-sulfamethoxazole 1

Medications to Avoid:

• First-generation cephalosporins (e.g., cephalexin) 1
• Penicillinase-resistant penicillins (e.g., dicloxacillin) 1
• Macrolides (e.g., erythromycin) 1
• Clindamycin alone (poor activity against P. multocida) 1

Duration of Treatment

• For uncomplicated infections: 3-5 days 1
• For complications such as:
  • Osteomyelitis: 4-6 weeks 1
  • Septic arthritis/synovitis: 3-4 weeks 1

Special Considerations

Tetanus Prophylaxis

• Administer tetanus toxoid if vaccination is not current (within 10 years) 1
• Tetanus, diphtheria, and pertussis (Tdap) is preferred if not previously given 1

Rabies Prophylaxis

• Consult with local health officials to determine if rabies vaccination should be initiated 1
• Postexposure prophylaxis consists of immune globulin at presentation and vaccination on days 0,3,7, and 14 2

High-Risk Patients

• Extended antimicrobial therapy (3-5 days) is recommended for patients who are:
  • Immunocompromised 1
  • Asplenic 1
  • Have advanced liver disease 1
  • Have preexisting or resultant edema of the affected area 1
  • Have moderate to severe injuries, especially to the hand or face 1
  • Have injuries that may have penetrated the periosteum or joint capsule 1

Potential Complications to Monitor

• Septic arthritis 1
• Osteomyelitis 1
• Subcutaneous abscess formation 1
• Tendonitis 1
• Bacteremia (rare) 1
• Hand wounds are particularly concerning and require careful monitoring 3, 4

Follow-up Care

• Outpatients should be followed up within 24 hours either by phone or during an office visit 1
• If infection progresses despite appropriate antimicrobial and supportive therapy, hospitalization should be considered 1

Microbiology of Dog Bite Infections

• Mixed aerobic and anaerobic flora (average of 5 bacterial types per wound) 1
• Common pathogens include:
  • Pasteurella species (found in 50% of dog bite wounds) 1
  • Staphylococci and streptococci (found in ~40% of bites) 1
  • Anaerobes including Bacteroides, Fusobacterium, Porphyromonas, and Prevotella species 1, 5
  • Capnocytophaga canimorsus (rare but can cause serious infection in immunocompromised patients) 1