Dog Bites ✅

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

📚 About Dog Bite Risks

• Dog bites are often polymicrobial, commonly involving Pasteurella multocida, anaerobes, streptococci and staphylococci.
• Some bites are high risk for infection because dog teeth can cause puncture and crush injury with bacterial inoculation into deeper tissues.
• Higher-risk wounds include hand bites, puncture wounds, crush wounds, wounds near joints/tendons/bone, wounds with significant tissue damage, and delayed presentations.
• Higher-risk patients include people with diabetes, immunosuppression, asplenia, cirrhosis or significant liver disease, poor peripheral circulation, or prosthetic material nearby.
• ⚠️ Capnocytophaga canimorsus can cause overwhelming sepsis, especially in people with asplenia, alcohol excess, or liver disease.

🔍 Clinical Assessment

• Assess ABCs first if unwell, then pain, bleeding, depth, contamination, and neurovascular status.
• Examine and document range of movement, distal sensation, tendon function, capillary refill, pulses, and whether the wound may communicate with a joint or tendon sheath.
• Explore under local anaesthetic if needed; seek senior/surgical help early for hand wounds, deep punctures, facial wounds, suspected tendon/joint/bone injury, or extensive tissue loss.
• Red flags: rapidly spreading cellulitis, severe pain, crepitus, systemic toxicity, lymphangitis, deep-space hand infection, loss of function, or immunocompromised host.

🧪 Investigations

• X-ray: if fracture, foreign body, retained tooth, gas in soft tissue, or bony/joint involvement is suspected.
• Bloods: FBC, CRP, U&E, glucose, blood cultures if septic or systemically unwell.
• Wound culture: not routinely needed in a fresh uncomplicated bite; take cultures only if the wound is clinically infected, discharging, or failing treatment.

🩹 Wound Management

• Irrigation: use generous saline irrigation and remove debris. The exact volume is less important than a thorough washout.
• Debridement: remove devitalised tissue where appropriate.
• Closure:
  • 👐 Usually leave open if high risk of infection.
  • 🙂 Primary closure may be considered for selected low-risk facial wounds after meticulous washout because cosmesis matters and facial blood supply is good.
  • ⌛ Delayed closure can be considered later if needed.
• Elevate and immobilise bites near joints or involving the hand.

💊 Antibiotics

Important: Flucloxacillin, erythromycin, and clindamycin alone do not provide reliable cover for the typical organisms in dog bites, particularly Pasteurella. Seek specialist advice in pregnancy if co-amoxiclav is unsuitable, and in very young infants.

💉 Tetanus

• Do not use a simple shortcut alone such as “5 years for dirty wounds / 10 years for clean wounds”.
• Instead, classify the wound as clean, tetanus-prone, or high-risk tetanus-prone, and check whether the patient has had an adequate priming course (at least 3 doses for wound-risk assessment purposes).
• A clean wound in a fully immunised person often needs no immediate post-exposure treatment.
• Tetanus-prone or high-risk tetanus-prone wounds may require a reinforcing vaccine dose, and people with incomplete or uncertain immunisation may need vaccine plus TIG/HNIG according to UKHSA guidance.
• Patients who are severely immunosuppressed may need additional consideration even if previously immunised.

🦠 Rabies

• For bites occurring in the UK from ordinary domestic dogs, rabies risk is usually very low.
• Risk assessment depends on the country, the animal, and the type of exposure.
• Travel-related bites, imported animals, or bites in endemic areas should prompt urgent rabies risk assessment.
• For many non-immunised patients with an amber-risk exposure, current UKHSA guidance advises 4 vaccine doses on days 0, 3, 7, and 21.
• For red-risk exposures, add HRIG plus 4 vaccine doses on days 0, 3, 7, and 21.
• Immunosuppressed patients generally need HRIG plus 5 vaccine doses on days 0, 3, 7, 14, and 30.
• Discuss promptly with UKHSA / public health / infectious diseases.

📅 Follow-up & Safety-net

• Advise return urgently for fever, spreading redness, increasing swelling, discharge, severe pain, loss of function, numbness, or reduced movement.
• If treated for infection, reassess if symptoms worsen rapidly or do not start improving within 24–48 hours.
• Hand bites often need lower threshold for plastics / orthopaedics / hand surgery review.

🏥 Admission / Senior Review

• Systemic sepsis or haemodynamic instability
• Rapidly spreading infection or suspected necrotising soft tissue infection
• Deep-space hand infection, septic arthritis, osteomyelitis risk, tendon sheath involvement
• Bone, joint, tendon, nerve, or vascular injury
• Significant immunosuppression, asplenia, or cirrhosis
• Complex facial wounds or major tissue loss
• Safeguarding or inability to manage safely at home

📝 Documentation & Medico-legal

• Record wound size, depth, site, neurovascular exam, washout/debridement, and closure decision.
• Document tetanus status, rabies/travel assessment, antibiotics given, and safety-net advice.
• Consider photographs if appropriate and permitted.
• Think about safeguarding in children and vulnerable adults.

🩺 Case 1 – Child with Hand Bite

A 7-year-old boy is brought to ED after a bite to the right hand from a neighbour’s dog. There is a deep puncture wound in the first web space with early erythema. He is otherwise well. Management: thorough washout, careful tendon/joint assessment, likely antibiotic prophylaxis because this is a hand bite, tetanus assessment using UKHSA wound guidance, and rabies risk assessment based on where the bite occurred and the animal risk. Avoid: ❌ closing a deep hand puncture primarily without strong reason.

🩺 Case 2 – Septic High-Risk Adult

A 58-year-old man presents 24 hours after a dog bite to the leg with fever, rigors, spreading cellulitis, lymphangitis, hypotension, and tachycardia. He has diabetes and is on long-term steroids. Management: treat as sepsis, take bloods/cultures, give IV antibiotics, resuscitate, and involve surgery if deep infection or debridement is a concern. Avoid: ❌ assuming this is simple cellulitis in a high-risk host.

Teaching Commentary 🧑‍⚕️

Dog bites are high risk not just because of the bacteria, but because the injury pattern is often deceptive: a small puncture at the surface may hide deep inoculation into tendon sheath, joint capsule, or poorly perfused crushed tissue. That is why hand bites, immunosuppression, and delayed presentation matter so much. The microbiology is broad, so narrow Gram-positive-only cover such as flucloxacillin alone is unsafe. In UK practice, the smartest approach is to think in layers: wound mechanics, host risk, deep structure involvement, then tetanus and rabies as separate prophylaxis decisions.

📚 References

• NICE NG184: Human and animal bites: antimicrobial prescribing.
• UKHSA Green Book, Chapter 30: Tetanus.
• UKHSA: Rabies – summary of risk assessment and treatment (updated 2025).
• NICE CKS / NHS bite wound guidance for wound care and follow-up principles.