What is the management for a dog bite to the thumb?

Management of Dog Bite to the Thumb

For a dog bite to the thumb, immediately irrigate copiously with sterile saline, start amoxicillin-clavulanate prophylaxis, avoid primary closure, ensure tetanus is current, confine and observe the dog for 10 days if available, and arrange follow-up within 48-72 hours to monitor for infection, osteomyelitis, or septic arthritis. 1

Immediate Wound Management

Thorough irrigation is your most critical intervention to prevent infection and potential rabies transmission. 1

• Cleanse immediately with soap and water, followed by copious irrigation using sterile normal saline 1
• Consider adding povidone-iodine solution to the irrigation to reduce infection risk 1
• Explore the wound carefully for tendon involvement, bone penetration, and foreign bodies - this is particularly important in thumb bites where functional structures are superficial 1
• Plain radiographs should be obtained to rule out fractures and foreign bodies, as X-rays will reveal 88% of retained foreign material 2
• Remove all devitalized tissue and foreign bodies 3
• Document neurovascular function including pulses, sensation, and range of motion of the interphalangeal and metacarpophalangeal joints 3

Closure Decision

Do not primarily close the thumb wound - hand bites carry exceptionally high infection risk. 1

• Non-facial wounds, especially hand injuries, should not be closed primarily but may be approximated rather than fully closed 1
• Hand injuries have significantly higher infection risk compared to other anatomical locations 1
• The thumb's limited soft tissue coverage and proximity to bone and joints increases the risk of deep space infections, septic arthritis, and osteomyelitis 4

Antibiotic Prophylaxis

Start amoxicillin-clavulanate immediately - this is your first-line antibiotic choice. 5, 1

• Amoxicillin-clavulanate covers Pasteurella multocida (present in 50% of dog bites), staphylococci, streptococci, and anaerobes 5, 1
• Dog bite wounds yield an average of 5 bacterial species, with approximately 60% containing mixed aerobic and anaerobic bacteria 5
• Avoid first-generation cephalosporins (like cephalexin), penicillinase-resistant penicillins, macrolides, or clindamycin alone - these have poor activity against Pasteurella multocida 5, 1
• Alternative oral agents if amoxicillin-clavulanate is contraindicated include doxycycline or a fluoroquinolone plus metronidazole 5
• Continue antibiotics for 3-5 days prophylactically, or longer if infection develops 1

Tetanus and Rabies Assessment

Update tetanus if the patient hasn't received vaccination within 10 years. 1

For rabies evaluation:

• If the dog is healthy and domestic, confine and observe for 10 days without starting rabies prophylaxis 5, 1
• Rabies vaccine should not be administered to the dog during the observation period 5
• If the dog is stray, unwanted, or cannot be observed, euthanize immediately and submit the head for rabies examination while initiating post-exposure prophylaxis 5, 1
• Rabies PEP consists of rabies immunoglobulin at presentation plus vaccine on days 0,3,7, and 14 for unvaccinated persons 1

Critical Follow-Up

Schedule follow-up within 48-72 hours - this is non-negotiable for thumb bites. 1, 3

Monitor specifically for:

• Signs of infection (erythema, warmth, purulent drainage, increasing pain) 1
• Osteomyelitis - particularly concerning in thumb bites due to proximity of bone; has a latency period of approximately 2 weeks and may require MRI or bone scan if suspected 4
• Septic arthritis - cat bites have higher rates, but dog bites to the thumb can penetrate the interphalangeal joints 5
• Tendonitis or tenosynovitis 1
• Capnocytophaga canimorsus bacteremia if the patient is asplenic or has liver disease 5

Common Pitfalls to Avoid

• Never close hand wounds primarily - the infection risk is too high and can lead to devastating complications including amputation in severe cases 1
• Don't use inadequate antibiotics - monotherapy with cephalexin or dicloxacillin will miss Pasteurella coverage 5, 1
• Don't dismiss delayed presentations - patients presenting >8 hours after injury typically have established infection and require more aggressive management 5
• Don't forget imaging - thumb bites can cause fractures and retain foreign bodies that complicate healing 2