What is the typical dose of doxycycline (tetracycline antibiotic) for treating animal bites?

Doxycycline for Animal Bite Treatment

For animal bites requiring antibiotic therapy, doxycycline 100 mg twice daily is an acceptable alternative agent, but amoxicillin-clavulanate 875/125 mg twice daily remains the first-line treatment due to superior coverage of the polymicrobial flora typically found in bite wounds. 1

First-Line Therapy

• Amoxicillin-clavulanate is the preferred oral antibiotic for animal bites, providing coverage against the mixed aerobic and anaerobic bacteria commonly present in these wounds, including Pasteurella multocida, Staphylococcus aureus, and anaerobes. 1, 2
• The standard dose is 875/125 mg twice daily for both dog and cat bites. 1
• For severe infections requiring intravenous therapy, ampicillin-sulbactam 1.5-3.0 g every 6-8 hours is recommended. 1, 2

Doxycycline as an Alternative

• Doxycycline 100 mg twice daily is listed as an alternative oral agent for animal bites, particularly useful in penicillin-allergic patients. 1, 2
• Doxycycline has excellent activity against Pasteurella multocida, the most common pathogen in cat and dog bites. 1
• Important limitation: Some streptococci are resistant to doxycycline, which is a critical gap since streptococcal species are commonly present in bite wounds. 1

Duration of Treatment

• Prophylaxis for high-risk wounds: 3-5 days (wounds involving hands, puncture wounds, immunocompromised patients, or presentation >12-24 hours after bite). 2
• Established infections: 7-10 days depending on clinical response. 2

When to Use Doxycycline

Doxycycline is most appropriate when:

• Penicillin allergy prevents use of amoxicillin-clavulanate. 1, 2
• The patient is not pregnant and is ≥8 years old (doxycycline is contraindicated in younger children and pregnant/breastfeeding women). 1, 3
• The bite is from an animal where Pasteurella coverage is paramount. 1

Critical Caveats

• Doxycycline monotherapy misses MRSA and has poor activity against some anaerobes, which may be present in bite wounds. 1
• For human bites, doxycycline is acceptable but must cover Eikenella corrodens (which it does) along with staphylococci and anaerobes. 1
• Combination therapy may be needed: Consider adding metronidazole 250-500 mg three times daily if anaerobic coverage is inadequate. 1

Standard Dosing from FDA Label

• Adults: 200 mg on day 1 (100 mg every 12 hours), then 100 mg twice daily for maintenance. 3
• Children >8 years and >100 lbs: Use adult dosing. 3
• Children >8 years and <100 lbs: 2 mg/lb divided into two doses on day 1, then 1 mg/lb daily (can increase to 2 mg/lb for severe infections). 3

Additional Management Essentials

• Thorough wound irrigation and debridement are critical first steps before antibiotic therapy. 2
• Tetanus prophylaxis must be updated if not current within 10 years (Tdap preferred over Td if not previously given). 1
• Prophylactic antibiotics show marginal benefit for low-risk dog bites presenting within 12-24 hours, but are recommended for high-risk wounds (hand injuries, puncture wounds, immunocompromised hosts). 1

Common Pitfalls

• Do not delay antibiotic therapy in high-risk wounds—this leads to poor outcomes. 2
• Do not use doxycycline in children <8 years old or pregnant women—no effective short-course alternative exists, but treatment of established Lyme disease (if that develops) is highly effective. 1
• Do not assume all animal bites need antibiotics—prophylaxis for low-risk dog bites has limited evidence of benefit. 1, 4