Management of Dog Bite with Serous Drainage
Start oral amoxicillin-clavulanate 875/125 mg twice daily immediately, as this patient has an established infection requiring treatment antibiotics, not prophylaxis. 1, 2
Immediate Assessment and Treatment
The presence of serous drainage several days post-bite indicates established infection, which occurs in approximately 16% of dog bites and typically presents 8-12 hours or more after injury. 1 This patient is beyond the prophylaxis window and requires therapeutic intervention.
Antibiotic Selection
Amoxicillin-clavulanate is the first-line agent because it provides comprehensive coverage against the polymicrobial flora of dog bite infections, including both aerobic and anaerobic bacteria. 1, 2
Dog bite wounds yield an average of 5 bacterial species (range 0-16), with 60% containing mixed aerobic and anaerobic organisms. 1
Pasteurella species are isolated from 50% of dog bites and cause rapidly developing cellulitis with serosanguineous or purulent drainage within 12-24 hours. 1, 3, 4
Other common pathogens include Staphylococcus aureus, streptococci (40% of bites), Capnocytophaga canimorsus (which can cause fatal sepsis), and multiple anaerobes including Bacteroides, Fusobacterium, and Prevotella species. 1, 4
Alternative Antibiotic Options
If the patient cannot tolerate amoxicillin-clavulanate: 1, 2
- Doxycycline 100 mg twice daily (excellent activity against Pasteurella multocida, though some streptococci are resistant)
- Moxifloxacin 400 mg daily (monotherapy with good anaerobic coverage)
- Levofloxacin 750 mg daily PLUS metronidazole 500 mg three times daily
Avoid clindamycin monotherapy as it misses Pasteurella multocida, a predominant pathogen. 1
Treatment Duration
- For uncomplicated soft tissue infection: 7-10 days of antibiotics 1
- For septic arthritis: 4 weeks 2
- For osteomyelitis: 6 weeks 2
Wound Management
- Do NOT primarily close this wound - it already has drainage indicating infection. 2
- Perform thorough irrigation with sterile normal saline and debridement of any devitalized tissue. 2
- The wound should be left open to drain or loosely approximated at most. 2
Critical Pitfall: Hand Wounds
If this bite involves the hand, the patient requires more aggressive management as hand wounds have a 2.08-fold increased risk of secondary presentations and infectious complications. 5 Hand bites frequently lead to deep tissue infections and osteomyelitis due to the complex anatomy and proximity to joints and bone. 2, 5, 3
Mandatory Follow-Up
- Schedule follow-up within 48-72 hours to assess response to antibiotics and wound healing. 2
- If infection progresses despite appropriate therapy, hospitalization should be considered for IV antibiotics. 2
Tetanus Prophylaxis
Administer tetanus toxoid if the patient has not received vaccination within 10 years, with Tdap preferred over Td if not previously given. 1, 2
Rabies Assessment
Consult local health officials regarding rabies risk. 2 If the dog is healthy and available, it should be confined and observed for 10 days without administering rabies vaccine during observation. 2 If the dog is stray, unwanted, or cannot be observed, initiate rabies post-exposure prophylaxis immediately. 2
Warning Signs Requiring Hospitalization
Watch for: 2
- Fever or systemic symptoms (suggesting bacteremia or sepsis)
- Rapidly spreading erythema or lymphangitis
- Abscess formation
- Signs of septic arthritis (joint pain, swelling, decreased range of motion)
- Failure to improve within 48 hours of appropriate antibiotics