What is the best course of treatment for a patient with mild degenerative changes in the carpometacarpal joint of the thumb, no evidence of acute displaced fracture, and a recent dog bite, to prevent infection and manage symptoms?

Management of Dog Bite with Mild Thumb CMC Degenerative Changes

Start amoxicillin-clavulanate 875/125 mg twice daily for 3-5 days immediately to prevent infection from the dog bite, while managing the pre-existing mild thumb arthritis conservatively with observation only. 1, 2

Immediate Priority: Dog Bite Infection Prevention

The dog bite takes absolute precedence over the incidental finding of mild degenerative changes. Preemptive antibiotic therapy is strongly recommended for 3-5 days for hand injuries from dog bites, which have high infection risk due to potential penetration of the periosteum or joint capsule. 1

Antibiotic Selection

• Amoxicillin-clavulanate 875/125 mg twice daily is the first-line agent, providing coverage against Pasteurella species (isolated from 50% of dog bite wounds), Staphylococcus, Streptococcus, and anaerobes that comprise the polymicrobial flora of dog bites 1, 2
• For penicillin allergy: doxycycline 100 mg twice daily has excellent activity against Pasteurella multocida, though some streptococci may be resistant 1, 2
• Avoid first-generation cephalosporins, macrolides, or clindamycin alone—these have poor activity against Pasteurella multocida 2

Essential Wound Care

• Copious irrigation with sterile normal saline using a 20-mL or larger syringe to adequately cleanse the wound and decrease bacterial load 2
• Cautious debridement of only devitalized tissue while preserving viable tissue, especially critical for hand wounds 1, 2
• Assess for nerve, tendon, or joint capsule penetration, which would increase infection risk and may require specialized repair 2

Additional Required Interventions

• Administer tetanus prophylaxis if vaccination is not current within the past 5 years for this contaminated wound 1, 2
• Consult local health officials to determine if rabies post-exposure prophylaxis is indicated, as this may require both immunoglobulin and vaccine 1, 2
• Elevate the hand to reduce swelling and accelerate healing 2

Management of Mild CMC Degenerative Changes

The mild degenerative changes are an incidental radiographic finding that requires no specific treatment at this time. 3, 4

Conservative Approach for Mild Arthritis

• Observation only is appropriate for mild, asymptomatic or minimally symptomatic CMC arthritis, as many patients with radiographic changes remain minimally symptomatic 5
• If symptoms develop (pain on wringing movements, tenderness, stiffness, crepitus), initiate conservative measures including activity modification, splinting, and NSAIDs 4
• Intra-articular corticosteroids provide only transient relief and are generally reserved for more advanced symptomatic disease 3

Critical Monitoring Parameters

Signs Requiring Extended Antibiotic Therapy

• Watch for increasing pain, redness, swelling, or purulent discharge indicating established infection 2
• If osteomyelitis or septic arthritis develops (particularly concerning given proximity to the CMC joint), extend antibiotics to 2-4 weeks 1, 2
• Close follow-up within 24-48 hours is necessary to monitor for infection progression 2

Common Pitfalls to Avoid

• Do not delay antibiotic initiation—the hand location and potential joint involvement make this a high-risk wound requiring immediate preemptive therapy 1
• Do not use topical antibiotics alone—they cannot adequately address the polymicrobial flora of dog bites and are explicitly inadequate for bite wounds 2
• Do not close the wound if any signs of infection are present—only clean, uninfected wounds should receive primary closure 2
• Do not confuse the mild degenerative changes with acute injury—the imaging confirms no acute fracture, and the arthritis is a chronic, pre-existing condition unrelated to the dog bite 3, 5
• Do not overlook rabies risk assessment—all dog bites require evaluation for rabies prophylaxis regardless of other findings 1, 2