What is the management for a patient presenting with dog lice bites?

Management of Dog Lice Bites

Critical Clarification: Dog Lice Do Not Bite Humans

Dog lice (Trichodectes canis) are species-specific parasites that infest dogs but do not infest or bite humans. 1 If a patient presents with what they believe are "dog lice bites," the actual diagnosis is likely one of the following:

Most Likely Alternative Diagnoses

1. Dog Bite or Scratch Wounds

If the patient has actual wounds from dog contact, management follows this algorithm:

Immediate Wound Care:

• Thoroughly irrigate with sterile normal saline using a 20-mL or larger syringe 2, 3
• Remove superficial debris and explore for foreign bodies, tendon, or bone involvement 4

Antibiotic Decision Algorithm:

• If presenting within 24 hours AND high-risk features present: Prescribe prophylactic antibiotics 4
  • High-risk features include: hand/foot/face/genital location, wounds near joints, deep/puncture wounds, immunocompromised status, diabetes, liver disease, asplenia, or prosthetic joints/valves 4
• If presenting ≥24 hours without infection signs: Do NOT prescribe antibiotics 4
• First-line antibiotic: Amoxicillin-clavulanate 875/125 mg twice daily for 7-10 days 4
• Alternatives: Doxycycline or moxifloxacin as monotherapy 4

Additional Prophylaxis:

• Tetanus toxoid 0.5 mL IM if vaccination not current within 10 years 4
• Rabies risk assessment: Consult local health officials; domestic dogs should be observed for 10 days 5

2. Human Lice Infestation (Pediculosis)

If the patient has actual lice infestation (head, body, or pubic lice from human-to-human transmission):

First-Line Treatment Options:

• Permethrin 1% cream rinse: Apply to affected areas, wash off after 10 minutes 6
• Pyrethrins with piperonyl butoxide: Apply to affected area, wash off after 10 minutes 6
• Lindane 1% shampoo: Apply for 4 minutes then wash off (NOT for pregnant/lactating women or children <2 years) 6

For Resistant Cases:

• Spinosad suspension, benzyl alcohol lotion, malathion, or ivermectin lotion 6
• Oral ivermectin 200-400 μg/kg for infants >15 kg, with second dose after 9-10 days 6

Environmental Decontamination:

• Machine wash or dry bedding/clothing using heat cycle, or remove from body contact for 72 hours 6
• Treat sex partners within preceding month for pubic lice 6

Follow-up:

• Re-evaluate after 1 week if symptoms persist 6

3. Allergic Reaction or Dermatitis from Dog Contact

Symptomatic Treatment:

• Over-the-counter hydrocortisone cream: For itching from minor skin irritations, insect bites, or contact dermatitis 7
• Calamine lotion: May help with lingering allergic reactions 8

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for dog bites presenting ≥24 hours without infection signs - this violates guidelines and promotes resistance 4
• Do not use first-generation cephalosporins, macrolides, or penicillinase-resistant penicillins alone for dog bite infections - poor activity against Pasteurella multocida (present in 50% of dog bites) 4
• Do not apply lice treatments to eyes - use occlusive ophthalmic ointment twice daily for 10 days for eyelash involvement 6
• Do not use lindane after bathing or in patients with extensive dermatitis - risk of seizures and aplastic anemia 6