Related Subjects: |Pasteurella Multocida |Capnocytophaga canimorsus |Snake Bites |Dog Bites |Tetanus

📚 About Dog Bite Risks

• Polymicrobial flora: Pasteurella, Capnocytophaga, anaerobes, staph/strep.
• High infection risk: hand, puncture/crush, near joints/prostheses, venous/lymphatic compromise, delayed presentation, diabetes, immunosuppression, asplenia, liver disease.
• ⚠️ Capnocytophaga canimorsus → fulminant sepsis in asplenic/cirrhotic patients even from minor bites.

🔍 Clinical Assessment

• Explore under anaesthesia if needed; check ROM, distal sensation, cap refill.
• Red flags: spreading cellulitis, pain out of proportion, crepitus, systemic toxicity, tendon/joint/bone involvement, immunocompromised host.

🧪 Investigations

• X-ray: suspected fracture, foreign body, retained tooth, hand/joint involvement.
• Bloods: FBC, CRP, U&E, glucose if systemic/unwell.
• Swab/culture: only if clinically infected or failing therapy.

🩹 Wound Management

• Irrigation: high-pressure saline (e.g. 35-mL syringe + 18G catheter).
• Closure:
  • 👐 Leave open: hand, puncture, crush, >12–24 h old, immunocompromised.
  • 🙂 Primary closure: face/scalp (<12 h, well-vascularised) after thorough washout.
  • ⌛ Delayed primary closure (48–72 h) if intermediate risk.
• Immobilise & elevate wounds near joints/hand.

💊 Antibiotics (must cover Pasteurella + anaerobes)

Notes: Flucloxacillin, erythromycin, and clindamycin alone are inadequate (no Pasteurella cover). Avoid doxy/fluoroquinolones in pregnancy & young children – seek specialist advice.

💉 Tetanus

• Bites = tetanus-prone. Booster if >5 years since last dose (dirty wound) or >10 years (clean wound).
• Give TIG if immunisation incomplete/unknown and wound tetanus-prone.

🦠 Rabies

• Negligible in UK from vaccinated domestic dogs. ⚠️ Consider after travel/unknown animal in endemic areas.
• PEP (naïve): vaccine days 0,3,7,14 (+ day 28 if immunocompromised) + HRIG infiltrated around wound for category III exposures.
• Discuss with infectious diseases/public health; act promptly.

📅 Follow-up & Safety-net

• Re-examine in 24–48 h (earlier for hand/face/high-risk). Mark cellulitis margins.
• Escalate for spreading erythema, fever, severe pain, loss of function, systemic toxicity.
• Hand bites: plastics/orthopaedics review for tendon sheath/joint involvement.

🏥 Admission / Senior Review

• Systemic sepsis, rapidly spreading infection, deep space/osteomyelitis risk.
• Involvement of bone, joint, tendon, or nerve.
• Immunocompromised, asplenic, cirrhotic patients.
• Facial wounds needing complex repair.
• Concerns about home support or safeguarding.

📝 Documentation & Medico-legal

• Photographs, wound size, neurovascular exam, washout volume, closure decision.
• Record tetanus/rabies risk, antibiotics given, and rationale.
• Safeguarding: children/vulnerable adults → consider abuse; report to public health/animal control as appropriate.

Cases — Dog Bite

• Case 1: A 7-year-old boy is brought to A&E after being bitten on the right hand by a neighbour’s dog. There is a deep puncture wound between the thumb and index finger with surrounding erythema. His tetanus immunisation is up to date, but the dog’s vaccination history is unknown. Parents are anxious about infection and rabies risk.
• Case 2: A 58-year-old man presents with fever, rigors, and spreading cellulitis 24 hours after being bitten on the leg by his own dog. He is diabetic and on long-term steroids for COPD. Examination shows erythematous, warm tissue with lymphangitis up the thigh. He is hypotensive and tachycardic on arrival.

Teaching Commentary 🧑‍⚕️

Dog bites are deceptively high-risk because their teeth cause crush and puncture wounds, seeding bacteria deep into tissues. The most common pathogens include Pasteurella multocida, anaerobes, and skin flora such as Staph. aureus. In Case 1, the key issues are wound cleaning, tetanus cover, rabies consideration (rare in UK unless bite abroad), and prophylactic co-amoxiclav. In Case 2, host factors (diabetes, steroids) predispose to fulminant infection and even sepsis. Urgent IV antibiotics, sepsis resuscitation, and surgical input for possible debridement are vital. Always consider both the injury mechanism and the patient’s background risk when managing bites.