Dog & Human Bites

1. Topic Overview (Clinical Overview)

Summary

Mammalian bites (Dog, Cat, Human) are common injuries with significant infection risk due to inoculation of polymicrobial oral flora deep into tissues. Dog bites account for 60-90% of mammalian bite injuries presenting to emergency departments; Cat bites, though less common, have disproportionately high infection rates (30-50%) due to sharp teeth creating deep puncture wounds; Human bites, particularly the "Fight Bite" (clenched fist injury over metacarpophalangeal joint), carry the worst prognosis due to joint capsule penetration and aggressive bacterial flora. [1,2]

Key organisms include Pasteurella multocida (Dogs/Cats - causes rapid cellulitis within 24 hours), Capnocytophaga canimorsus (Dogs - potentially fatal in asplenic/immunocompromised patients), and Eikenella corrodens (Human bites - "corrodes" agar, aggressive soft tissue destruction). Management principles include thorough wound irrigation with high-pressure saline, appropriate antibiotic prophylaxis (Co-Amoxiclav is first-line, covering Pasteurella, Eikenella, Staphylococcus, Streptococcus, and anaerobes), Tetanus prophylaxis, assessment for Rabies risk, and careful consideration of wound closure (Facial bites typically closed due to excellent blood supply; Hand/puncture wounds often left open or delayed closure). [3,4]

Key Facts

• Dog Bites: Most common (60-90%). Crush injuries. Pasteurella multocida. Capnocytophaga (Asplenic).
• Cat Bites: Deep punctures. High infection rate (30-50%). Pasteurella (Fast onset less than 24h).
• Human Bites: "Fight Bite" = Clenched fist injury over MCP. Eikenella corrodens. High complication rate (up to 50%).
• Antibiotic: Co-Amoxiclav (Covers Pasteurella, Staph, Strep, Eikenella, Anaerobes). [4]
• Closure: Facial bites – Primary closure (Good blood supply). Hand/Puncture – Leave open or delayed primary closure. [5]
• Tetanus: Booster if > 10 years (or > 5 years if tetanus-prone wound).
• Rabies: Assess risk (Animal source, Country, Vaccination status). Post-exposure prophylaxis if indicated. [6,7]

Clinical Pearls

"Fight Bite = Septic Arthritis Until Proven Otherwise": A wound over MCP in a clenched fist position likely penetrated the joint capsule when the hand was closed. When the hand extends, the skin wound moves proximally relative to the underlying joint, creating a valve mechanism that prevents drainage. Treat aggressively with surgical exploration, washout, and IV antibiotics. [8,9]

"Cat Bites Infect Fast": Small puncture wounds inoculate Pasteurella bacteria deep into tissues. Infection develops within 12-24 hours, often presenting as rapidly progressive cellulitis with purulent discharge. [3]

"Capnocytophaga in Asplenic Patients = Fulminant Sepsis": Dog bites in asplenic patients can cause rapid, overwhelming septicaemia with DIC, purpura fulminans, and multi-organ failure. Mortality approaches 30% even with treatment. [10,11]

"Co-Amoxiclav Covers Everything": First-line antibiotic for mammalian bites. Amoxicillin covers Pasteurella and Eikenella; clavulanic acid covers beta-lactamase-producing Staphylococcus and Bacteroides. [4]

"Hand Bites Never Trivial": The hand has multiple closed compartments (tendon sheaths, joints, fascial spaces). Bacterial inoculation can rapidly spread, causing tenosynovitis, septic arthritis, or compartment syndrome.

Why This Matters Clinically

Bite injuries cause significant morbidity through infection-related complications. Approximately 250,000 patients present to UK emergency departments annually with bite injuries. [1] Early recognition of high-risk wounds (Cat bites, Human fight bites, Hand location, Immunocompromised host) and prompt antibiotic therapy prevent serious complications including septic arthritis, osteomyelitis, and septicaemia. Delayed presentation (> 24 hours) increases infection risk substantially, with established infections requiring IV antibiotics, surgical drainage, or amputation in severe cases. [2,8]

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2. Epidemiology

Incidence & Prevalence

Globally, an estimated 4.5 million dog bites occur annually in the United States alone, with 10-20% requiring medical attention. [1,2]

Risk Factors for Infection

Microbiology Statistics

• Polymicrobial infection: 50-80% of bite wound infections grow multiple organisms. [4]
• Pasteurella multocida: Isolated in 50% of dog bite infections and 75% of cat bite infections. [3]
• Staphylococcus aureus: Present in 20-30% of dog bites and 30-40% of human bites. [4]
• Anaerobes (Bacteroides, Fusobacterium, Prevotella): Found in 40-60% of infected bite wounds. [4]

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3. Microbiology & Pathophysiology

Organisms by Bite Type

Dog Bites

Cat Bites

Human Bites

Special Organisms: Detailed Profiles

Pasteurella multocida

Microbiology: Small, Gram-negative coccobacillus. Facultative anaerobe. Oxidase-positive. Non-motile. [3]

Pathogenesis:

• Produces endotoxin (lipopolysaccharide) causing intense inflammatory response
• Capsule (polysaccharide) inhibits phagocytosis
• Adhesins bind to respiratory epithelium and damaged tissue
• Inoculated deep by sharp cat teeth or crushing dog bite
• Rapid multiplication in damaged tissue → cellulitis within 12-24 hours

Clinical Features: [3]

• Onset: 12-24 hours post-bite (contrast with Staph/Strep: 2-5 days)
• Appearance: Erythema, warmth, edema, serosanguinous or purulent discharge
• Pain: Disproportionate to appearance
• Spread: Along fascial planes. Can cause tenosynovitis, septic arthritis, osteomyelitis
• Systemic: Bacteremia in immunocompromised (rare but serious)

Treatment: Penicillin/Amoxicillin (first-line). Co-amoxiclav. Doxycycline (penicillin-allergic). Avoid macrolides (resistance increasing).

Eikenella corrodens

Microbiology: Gram-negative bacillus. Facultative anaerobe. Oxidase-positive. "Corrodes" agar (pitting colonies). Indole-positive. [12]

Pathogenesis:

• Part of normal human oral flora (gingival crevices)
• Adhesins bind to damaged tissue
• Produces proteases → tissue destruction
• Forms biofilms → antibiotic resistance
• Associated with periodontal disease (poor dentition increases inoculum)

Clinical Features: [8,12]

• Associated with: Clenched fist injuries ("fight bite"), human bites, injection drug use (licking needles)
• Onset: 24-48 hours
• Appearance: Seropurulent discharge with foul odor
• Aggressive: Rapid spread along tendon sheaths, into joints
• Complications: Septic arthritis, osteomyelitis, endocarditis (rare)

Treatment: Penicillin/Amoxicillin (first-line). Co-amoxiclav. Resistant to clindamycin, metronidazole alone. Surgical drainage often required.

Capnocytophaga canimorsus

Microbiology: Gram-negative, fusiform bacillus. Fastidious (slow-growing). Capnophilic (requires CO₂). Part of normal dog/cat oral flora. [10,11]

Pathogenesis:

• Polysaccharide capsule → resistance to complement-mediated killing
• Overwhelming infection in asplenic patients: Spleen normally removes encapsulated organisms. Without spleen, bacteremia → septic shock
• Endotoxin release → DIC, cytokine storm, multi-organ failure

Clinical Features (Asplenic/Immunocompromised): [10,11]

• Incubation: 1-8 days (median 3 days)
• Presentation: Fever, chills, myalgia → rapidly progressive septic shock
• Dermatologic: Purpura fulminans (disseminated intravascular coagulation), peripheral gangrene, acral necrosis
• Multi-organ failure: ARDS, AKI, hepatic dysfunction
• Mortality: 25-30% despite treatment
• Other complications: Meningitis, endocarditis, septic arthritis (rare)

Risk Groups: [10]

• Asplenia (surgical, functional)
• Chronic liver disease (cirrhosis, alcohol abuse)
• Immunosuppression (chemotherapy, high-dose steroids, biologics)
• Chronic lung disease

Treatment: High index of suspicion. Immediate empirical antibiotics (Co-amoxiclav or Piperacillin-tazobactam). ICU support. Exchange transfusion (case reports). Prevention: Prophylactic antibiotics for dog/cat bites in asplenic patients.

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4. Clinical Presentation

History Taking

Examination

Wound Assessment

Neurovascular Examination

Joint Examination

Red Flag: ANY wound over MCP joint in context of punching someone = mandatory exploration for joint penetration.

Wound Classification

By Type

High-Risk Wounds (Requiring Antibiotics)

Special Scenario: "Fight Bite" (Clenched Fist Injury)

Mechanism: Punching someone in the teeth. Tooth penetrates skin over MCP joint (usually 3rd or 4th). [8,9]

Why Dangerous: [8]

• Joint Penetration: When fist is clenched (at time of injury), MCP joint is flexed. Tooth penetrates joint capsule.
• Valve Effect: When hand opens (after injury), skin wound moves 5-10mm proximally relative to underlying joint. Creates one-way valve → bacteria trapped in joint.
• Inoculation: Human oral flora (Eikenella, Streptococcus, anaerobes) directly into joint.
• Delay: Often patient doesn't present for 24-48 hours ("It's just a small cut"). By then, septic arthritis established.

Clinical Features:

• Wound: Small (5-10mm) laceration over MCP, dorsum of hand
• Often: Patient claims "fell on glass" or "cut it on something" (embarrassed to admit fight)
• Presentation: Swelling, erythema, pain, unable to make fist
• Late presentation: Purulent discharge, fever, systemic symptoms

Complications (if untreated): [8,9]

• Septic arthritis (50%)
• Osteomyelitis (10-20%)
• Flexor tenosynovitis (spread to palmar side)
• Chronic stiffness, loss of function
• Amputation (rare but reported)

Management: [8,9]

• X-Ray: Tooth fragment? Fracture? Gas in soft tissues?
• Admit: IV antibiotics (Co-amoxiclav or Piperacillin-tazobactam)
• Surgical Exploration: Theatre washout. Open joint capsule, irrigate copiously (3-6L saline). Debride necrotic tissue. Leave wound open (pack loosely). Delayed primary closure after 3-5 days if clean.
• Hand Surgery referral: Urgent (same day)
• Antibiotics: IV for 48-72 hours, then oral to complete 7-10 days
• Occupational therapy: Early mobilization to prevent stiffness

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5. Investigations

Wound Culture

Culture Interpretation:

• Positive culture: Tailor antibiotics to sensitivities
• Negative culture: Does not rule out infection (fastidious organisms, prior antibiotics)
• Polymicrobial growth: Common (50-80%). Usually includes aerobes + anaerobes.

Imaging

X-Ray Indications

Advanced Imaging

Blood Tests

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6. Management

Initial Assessment & Triage

ABCDE Approach (if major trauma, systemic sepsis, or anaphylaxis):

• Airway: Facial/neck bites (swelling, hematoma). Secure if compromised.
• Breathing: Chest bites (pneumothorax). Sepsis (tachypnea, hypoxia).
• Circulation: Major vascular injury (rare). Septic shock (hypotension, tachycardia).
• Disability: Conscious level (sepsis, meningitis). Neurovascular status of limb.
• Exposure: Full examination. Document all injuries. Photography.

Wound Management Principles

1. Analgesia

Adequate pain relief before wound exploration:

• Oral: Paracetamol 1g QDS + Ibuprofen 400mg TDS (if not contraindicated)
• Opiates: Codeine, Tramadol, Morphine (severe pain)
• Local anesthesia: Lidocaine 1% (max 3mg/kg) or Bupivacaine 0.25% (longer-acting). Avoid digital ring blocks with adrenaline (risk of ischemia). Beware contaminated wounds (local anesthetic may not work well in acidic infected tissue).

2. Wound Irrigation

MOST IMPORTANT INTERVENTION to prevent infection. [1,2,5]

Technique:

• High-pressure irrigation: 20-50ml syringe + 18G needle or splash guard
• Volume: Minimum 250-500ml Normal Saline (or clean tap water). Up to 1-3L for large/contaminated wounds.
• Mechanism: Mechanical removal of bacteria, debris, saliva. Reduces bacterial load by 90-99%.
• Avoid: Hydrogen peroxide, alcohol, povidone-iodine in wound (cytotoxic to tissues). Can clean surrounding skin with chlorhexidine.

Evidence: High-pressure irrigation reduces infection rates. [5]

3. Debridement

Indications:

• Devitalized tissue (white, non-bleeding, non-viable)
• Necrotic tissue (black eschar)
• Heavily contaminated tissue
• Foreign material (cannot be irrigated out)

Technique:

• Sharp debridement: Scalpel or scissors
• Conservative: Remove only obviously non-viable tissue (especially on face, hands)
• Preserve critical structures: Nerves, vessels, tendons (even if damaged - can be repaired)

Caution: Over-aggressive debridement on hand can worsen function. Err on conservative side; reassess in 24-48 hours.

4. Exploration

Indications for Formal Exploration (Operating Theatre):

• Fight Bite (suspected joint penetration)
• Deep hand/foot wounds (tendon/nerve/vessel injury)
• Suspected foreign body (tooth fragment)
• Abscess requiring drainage
• Necrotizing infection

Technique:

• Anesthesia: General or regional block
• Tourniquet: Improve visualization (hand/foot)
• Extend wound if necessary to visualize structures
• Test tendon function directly (if continuity in doubt)
• Open joint capsule if suspected penetration → copious irrigation
• Send tissue culture
• Leave wound open or loose packing (delayed closure)

Antibiotic Therapy

Indications for Prophylactic Antibiotics

Give antibiotics if ANY of the following: [4]

• ✅ Cat bite (any)
• ✅ Human bite (any that breaks skin)
• ✅ Hand bite (any animal)
• ✅ Puncture wound
• ✅ Bite near bone or joint
• ✅ Moderate to severe injury (crush, deep)
• ✅ Delayed presentation (> 12 hours, not yet infected)
• ✅ Immunocompromised (diabetes, steroids, asplenia, cirrhosis, HIV, chemotherapy)
• ✅ Wound requiring closure

No antibiotics needed:

• Minor, superficial dog bite (not on hand)
• Presenting within 6-12 hours
• Easily irrigable
• Not immunocompromised
• Good wound care performed

First-Line: Co-Amoxiclav (Amoxicillin + Clavulanic Acid)

Why Co-Amoxiclav? [4]

• Amoxicillin: Covers Pasteurella, Eikenella, Streptococcus, and is penicillin-core for Gram-positives
• Clavulanic acid: β-lactamase inhibitor → covers β-lactamase-producing Staphylococcus aureus, Bacteroides, and other anaerobes
• Broad spectrum: Single agent covering all major bite wound pathogens

Dosing:

Pregnancy/Breastfeeding: Safe.

If Penicillin Allergic

Non-Severe Allergy (rash only, not anaphylaxis):

Severe Allergy (anaphylaxis, angioedema):

Avoid:

• ❌ Macrolides alone (Erythromycin, Clarithromycin): Increasing Pasteurella resistance
• ❌ Clindamycin alone: Does NOT cover Pasteurella or Eikenella
• ❌ Flucloxacillin/Dicloxacillin: Does NOT cover Pasteurella

Treatment of Established Infection

Oral (Mild cellulitis, afebrile, no systemic symptoms):

• Co-Amoxiclav 625mg TDS for 7-10 days
• Review in 24-48 hours
• If worsening → admit for IV antibiotics

IV (Severe infection, sepsis, abscess, immunocompromised):

Duration: IV until afebrile for 48 hours and clinically improving, then switch to oral to complete 7-10 days total (cellulitis) or 4-6 weeks (osteomyelitis).

Monitoring: Daily review. Temperature, WCC, CRP. Mark cellulitis border with pen (dated) to track progression.

Special Populations: Asplenic Patients

ANY dog/cat bite in asplenic patient = Emergency. [10,11]

Protocol:

1. Immediate antibiotics: Co-Amoxiclav 1.2g IV (or Ceftriaxone 2g IV)
2. Admit for observation (24-48 hours minimum)
3. Low threshold for prolonged course: 7-10 days prophylaxis
4. Counsel patient: Lifelong advice card. Immediate presentation for any bite.
5. Blood cultures if any fever or systemic symptoms

Tetanus Prophylaxis

All mammalian bites are tetanus-prone wounds. [13]

Td = Tetanus-diphtheria toxoid (adult formulation). TIG = Tetanus Immunoglobulin (passive immunity).

Note: Tetanus booster can be given safely even if recent vaccination (no maximum frequency limit for post-exposure).

Rabies Risk Assessment

Rabies is almost 100% fatal once symptomatic. Post-Exposure Prophylaxis (PEP) is life-saving if given promptly. [6,7,14]

Epidemiology

• UK, Australia, New Zealand, Japan, Western Europe: Rabies-free (except bats in UK)
• High-risk regions: Asia (India, China, Thailand, Philippines), Africa, Latin America, Eastern Europe
• Reservoir: Dogs (99% of human cases globally), Bats, Foxes, Raccoons, Skunks, Monkeys
• Transmission: Saliva through bite, scratch, or lick on broken skin/mucous membranes

Risk Assessment Questions

Indications for Post-Exposure Prophylaxis (PEP)

Give PEP if:

• ✅ Bite in rabies-endemic country (even if minor, unless animal can be observed and remains healthy for 10 days)
• ✅ Wild animal bite (bat, fox, raccoon, skunk, monkey) in endemic or semi-endemic area
• ✅ Bat exposure in UK (bite, scratch, or bat contact with broken skin)
• ✅ Unprovoked bite from stray/unknown dog in endemic area
• ✅ Animal cannot be observed or shows abnormal behavior

PEP Not Needed:

• ❌ Domestic dog/cat bite in UK (unless bat exposure)
• ❌ Animal observable and healthy at 10 days
• ❌ Bite through intact clothing only (no skin contact)

Post-Exposure Prophylaxis (PEP) Protocol [6,7,14]

Components:

1. Wound Care: Immediate, thorough washing with soap and water for ≥15 minutes. Virucidal (reduces viral load by 90%). [14]
2. Rabies Immunoglobulin (RIG): Passive immunity. Infiltrate around wound (as much as anatomically feasible). Remainder given IM at distant site from vaccine.
   • Dose: 20 IU/kg (human RIG) or 40 IU/kg (equine RIG)
   • Timing: Ideally Day 0 (same day as first vaccine). Can give up to Day 7.
3. Rabies Vaccine: Active immunity. Intramuscular (deltoid or anterolateral thigh in children). NOT gluteal (poor immunogenicity).
   • Schedule (No pre-exposure vaccination): Day 0, 3, 7, 14, 28 (5 doses)
   • Schedule (Previous pre-exposure vaccination): Day 0, 3 (2 doses). No RIG needed.

Urgent Referral: Contact Public Health (UKHSA in UK, CDC in USA) for PEP access and advice.

Contraindications to PEP: NONE. Rabies is fatal. PEP is safe in pregnancy, immunocompromised, elderly, children (all ages including neonates).

Wound Closure Decision

Critical Decision: Primary closure vs. leaving open vs. delayed closure. [5,15]

Primary Closure (Immediate)

Indications:

• ✅ Face/scalp (excellent blood supply, cosmetic importance) [5,15]
• ✅ Fresh wounds (less than 12 hours) in well-vascularized areas
• ✅ Low-risk bites (dog bite on trunk/proximal limb, not puncture, well-irrigated, patient reliable)
• ✅ No signs of infection

Technique:

• Loose sutures (avoid tight closure → increased pressure → ischemia → infection)
• Single layer (skin only) or two-layer (fascia, then skin)
• Consider leaving small gaps between sutures (partial closure) for drainage
• Follow-up: 24-48 hours

Evidence: Facial wounds have low infection rates even with primary closure due to rich vascularity. [5,15]

Leave Open (Secondary Intention or Delayed Primary Closure)

Indications:

• ✅ Hand bites (all) [5,9]
• ✅ Puncture wounds (cat bites, deep dog bites)
• ✅ Crush injuries (devitalized tissue)
• ✅ Delayed presentation (> 12-24 hours)
• ✅ Fight Bite (clenched fist injury)
• ✅ High-risk patients (immunocompromised, diabetes, asplenia)
• ✅ Signs of infection

Technique:

• Irrigate copiously
• Debride non-viable tissue
• Pack loosely with saline-soaked gauze or alginate dressing
• Dress: Non-adherent dressing, absorbent pad, bandage
• Elevate (hand: sling. Foot: crutches)
• Follow-up: 24-48 hours

Delayed Primary Closure (DPC): Re-assess at 3-5 days. If wound clean, granulating, no infection → can close with sutures or Steristrips. Better cosmetic outcome than complete secondary intention.

Surgical Wounds (After Exploration/Washout)

Usually LEFT OPEN:

• Fight bite post-washout
• Abscess drainage
• Necrotizing infection debridement

Closure at 3-5 days if clean.

Indications for Admission / Specialist Referral

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7. Complications

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8. Special Populations

Asplenic / Hyposplenic Patients

Why High-Risk: Spleen is primary site for clearance of encapsulated bacteria (Capnocytophaga, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis). Without functional spleen → Overwhelming Post-Splenectomy Infection (OPSI) syndrome. [10,11]

Capnocytophaga canimorsus in Asplenic Patients:

• Incidence: 0.5-0.67 per 1,000 person-years (500x higher than general population)
• Mortality: 25-30% (despite antibiotics and ICU care)
• Presentation: Rapidly progressive septic shock (median 3 days post-bite). DIC (purpura fulminans, peripheral gangrene). Multi-organ failure. [10,11]
• Prevention:
  • "Education: Avoid dog/cat bites. Lifelong advice card."
  • "Prophylactic antibiotics: ANY dog/cat bite → immediate Co-Amoxiclav (even if minor). Some experts recommend 7-10 days course."
  • "Immediate presentation: Any fever, malaise, or systemic symptoms → emergency department."
  • "Vaccinations: Up-to-date Pneumococcal, Haemophilus, Meningococcal, annual Influenza."
  • "Penicillin prophylaxis: Some patients on lifelong Penicillin V (consider if recurrent infections or high-risk behavior)."

Immunocompromised Patients

High-Risk Groups:

• Diabetes (especially if poor control, neuropathy, peripheral vascular disease)
• Cirrhosis / Chronic Liver Disease (impaired opsonization, Capnocytophaga risk)
• HIV/AIDS (CD4 less than 200)
• Chemotherapy (neutropenia)
• Immunosuppressants: High-dose steroids (> 20mg prednisolone > 2 weeks), Biologics (TNF-α inhibitors, Rituximab), DMARDs (Methotrexate, Azathioprine)
• Organ Transplant (on anti-rejection drugs)
• Chronic Kidney Disease (especially dialysis)

Management Modifications:

• Lower threshold for antibiotics: Give prophylaxis for minor wounds
• Longer courses: Consider 7-10 days instead of 5 days
• Lower threshold for admission: Observe 24-48 hours
• IV antibiotics earlier: If any signs of infection
• Broader coverage: Consider adding Flucloxacillin (MRSA risk) or upgrading to Piperacillin-Tazobactam

Children

Epidemiology:

• Children less than 10 years: Higher proportion of dog bites to head/neck (40-50%) due to height
• "Toddler bites": Occlusive bites from other toddlers (nursery, siblings)

Management Considerations:

• Safeguarding: Mandatory assessment if:
  • Bite inconsistent with history
  • Delay in seeking treatment
  • Multiple injuries
  • Parental behavior concerning
  • Human bite in non-ambulatory child (cannot be accidental)
• Antibiotics: Weight-based dosing. Avoid Doxycycline less than 12 years (teeth staining).
• Wound closure: Generally same principles (face: close, hand: leave open). Consider cosmetic impact (facial scars in children).
• Psychological support: Assess for trauma, fear, behavioral changes. Child psychology referral if needed.

Pregnancy

Safety of Interventions:

• Antibiotics:
  • ✅ Co-Amoxiclav: Safe in pregnancy
  • ✅ Metronidazole: Safe (avoid 1st trimester if possible, but use if needed)
  • ❌ Doxycycline: Contraindicated (teeth/bone in fetus)
  • ✅ Azithromycin: Safe alternative
• Tetanus vaccine: Safe
• Rabies PEP: Safe and ESSENTIAL (rabies is fatal). Both vaccine and immunoglobulin safe in pregnancy. [14]
• X-Rays: Shield abdomen. Low radiation exposure from hand/foot X-ray (acceptable if clinically indicated).

Elderly

Increased Risk:

• Comorbidities (diabetes, CKD, COPD)
• Polypharmacy (steroids, immunosuppressants)
• Impaired immunity
• Poor wound healing (vascular disease)
• Frailty (increased infection risk)

Management:

• Lower threshold for admission
• Careful assessment of function (cognitive, mobility)
• Falls risk (if dizzy from infection/antibiotics)
• Review medications (drug interactions)

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9. Evidence & Guidelines

Key Guidelines

Evidence Base

Antibiotic Prophylaxis

Systematic Reviews:

• Cochrane Review (2014): Antibiotic prophylaxis reduces infection rate in hand bites and full-thickness wounds. [16]
• Meta-analysis (Medeiros & Saconato, 2001): Prophylaxis reduces infection from 16% to 6% (NNT=10). [17]
• Co-Amoxiclav: Covers 95% of isolates from bite wounds. First-line recommendation. [4]

Wound Closure

• Primary closure of facial dog bites: Low infection rates (1-2%) even with immediate closure, due to rich vascularity. [5,15]
• Hand bites: Higher infection with primary closure (20-30%). Recommend leaving open or delayed closure. [9]
• Cat bites: Puncture wounds should NOT be closed (infection risk 30-50%). [3]

Wound Irrigation

• High-pressure irrigation reduces bacterial load by 90-99%, significantly decreasing infection rates. [18]
• Optimal volume: ≥250ml for small wounds, 1-3L for large/contaminated wounds. [2]

Capnocytophaga in Asplenic Patients

• Case series (2022): Mortality 25-30% in asplenic patients with Capnocytophaga sepsis, even with treatment. [10,11]
• Recommendation: Prophylactic antibiotics for ALL dog/cat bites in asplenic patients. [11]

Fight Bite

• Studies (Shewring et al., 2015; Kay et al., 2021): Complication rate 50% if delayed presentation. Urgent surgical washout reduces complications to 10-15%. [8,9]
• Recommendation: Mandatory exploration for clenched fist injuries over MCP. [8,9]

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10. Exam Scenarios (MCQs & Viva)

Scenario 1: Fight Bite (Clenched Fist Injury)

Clinical Stem: A 24-year-old man presents to the Emergency Department with a 3cm laceration over the dorsum of his right hand, overlying the 4th MCP joint. He claims he "cut it on a fence" 18 hours ago. On examination, there is surrounding erythema, purulent discharge, and he is unable to fully extend or flex the 4th finger without pain.

Questions:

1. What is the most likely mechanism of injury?
2. What is the most concerning complication?
3. What investigation should be performed?
4. What is the definitive management?

Model Answers:

1. "Fight bite" (clenched fist injury). The laceration over MCP joint in a young male, with the history of "cut on fence" (often patients embarrassed to admit fight), suggests punching someone in the teeth. [8]
2. Septic arthritis of the MCP joint. When the fist was clenched, the tooth penetrated the joint capsule. When the hand extended, the skin wound moved proximally, creating a valve effect → bacteria trapped in joint → infection. Eikenella corrodens (human oral flora) is aggressive. [8]
3. X-Ray (AP, Lateral, Oblique views of hand): Look for (1) Tooth fragment, (2) Fracture of metacarpal head, (3) Gas in soft tissues (gas-forming infection), (4) Joint space widening (effusion).
4. Urgent Hand Surgery referral. Admission. IV Co-Amoxiclav 1.2g TDS. Theatre washout: Extend wound, open joint capsule, copious irrigation (3-6L saline), debride necrotic tissue. Leave wound open (loose packing). Delayed primary closure at 3-5 days if clean. IV antibiotics for 48-72 hours, then oral to complete 7-10 days total. [8,9]

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Scenario 2: Cat Bite - Pasteurella Infection

Clinical Stem: A 55-year-old woman presents 18 hours after being bitten on the left hand (dorsal aspect, 3rd web space) by her cat. She has a small puncture wound (~3mm), but there is significant swelling, erythema extending up the dorsum of the hand, warmth, and serosanguinous discharge. She is afebrile. She is allergic to penicillin (rash only, not anaphylaxis).

Questions:

1. What is the most likely organism?
2. Why do cat bites have high infection rates?
3. What is the appropriate antibiotic therapy?
4. Should the wound be closed?

Model Answers:

1. Pasteurella multocida (75% of cat bite infections). Rapid onset of cellulitis (12-24 hours) is characteristic. [3]
2. Sharp, pointed teeth create deep puncture wounds that:
   • Inoculate bacteria deep into tissues (subcutaneous, muscle, tendon sheaths, joints)
   • Cannot be adequately irrigated (small entrance, deep tract)
   • Skin seals quickly → closed space infection
   • Infection rate 30-50% (vs. 5-15% for dog bites). [3]
3. Penicillin allergy (non-severe): Doxycycline 100mg BD + Metronidazole 400mg TDS for 7-10 days (treatment, as already infected). Covers Pasteurella, Staphylococcus, Streptococcus, anaerobes. [4]
   • Alternatives: Levofloxacin + Metronidazole, or Moxifloxacin (monotherapy).
   • Avoid: Macrolides alone (increasing Pasteurella resistance), Clindamycin alone (does NOT cover Pasteurella).
4. No, do NOT close. Puncture wounds have high infection risk. Leave open, dress, elevate hand. Review in 24-48 hours. If improving, can heal by secondary intention or delayed primary closure at 5-7 days. [5]

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Scenario 3: Asplenic Patient - Dog Bite

Clinical Stem: A 40-year-old man with a history of splenectomy (following trauma 5 years ago) presents to the Emergency Department after being bitten on the forearm by a neighbor's dog 2 hours ago. The wound is a 4cm laceration, not heavily contaminated. He is currently well, afebrile, and has no signs of infection.

Questions:

1. What specific organism are you concerned about in this patient?
2. What is the management plan?
3. What advice should be given for future bites?

Model Answers:

1. Capnocytophaga canimorsus. This is a Gram-negative bacillus found in dog saliva (10-20% carriage). In asplenic patients, it can cause fulminant sepsis with DIC, purpura fulminans, and multi-organ failure. Mortality is 25-30% even with treatment. The spleen normally clears encapsulated organisms; without it, bacteremia progresses to overwhelming sepsis. [10,11]
2. Management:
   • Wound care: High-pressure irrigation (≥500ml saline). Debride if any devitalized tissue.
   • Antibiotics: Immediate IV Co-Amoxiclav 1.2g TDS (or oral 625mg TDS if definitely not admitting, but IV preferred). Duration: 7-10 days (longer than usual prophylaxis).
   • Admit for observation: 24-48 hours. Monitor for fever, hypotension, rash (purpura).
   • Tetanus: Check status, give booster if indicated.
   • Wound closure: Can close if facial or low-risk area. Leave open if hand or high-risk.
   • Follow-up: Daily review for 3-5 days (phone or in-person).
3. Lifelong Advice:
   • Avoid animal bites (caution around dogs/cats).
   • Carry alert card (asplenic patient).
   • Immediate antibiotics for ANY bite (keep course of Co-Amoxiclav at home if in remote area - controversial, but some experts recommend).
   • Immediate presentation to hospital if fever, malaise, or any systemic symptoms after bite.
   • Up-to-date vaccinations: Pneumococcal (5-yearly), Haemophilus, Meningococcal (ACWY + B), annual Influenza.
   • Consider prophylactic Penicillin V (some patients on lifelong prophylaxis). [10,11]

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Scenario 4: Rabies Risk Assessment

Clinical Stem: A 30-year-old backpacker presents to the Emergency Department 3 days after being bitten on the calf by a stray dog in India. The dog appeared healthy but ran away immediately. She washed the wound with bottled water. She is up-to-date with routine vaccinations but has not had pre-exposure rabies vaccination. The wound is a superficial laceration, not infected.

Questions:

1. What is the rabies risk in this scenario?
2. What is the appropriate management?
3. What if she had received pre-exposure rabies vaccination (e.g., for travel)?

Model Answers:

1. High rabies risk:
   • Country: India is rabies-endemic (one of the highest incidence globally, > 20,000 deaths/year). [7,14]
   • Animal: Stray dog (unknown vaccination status, cannot be observed for 10 days).
   • Exposure: Bite (saliva contact with broken skin = Category III exposure per WHO).
   • Rabies is almost 100% fatal once symptomatic → Post-Exposure Prophylaxis (PEP) is essential. [6,7,14]
2. Management:
   • Wound care: Immediate, thorough washing with soap and water for ≥15 minutes (already done, but reinforce). This is virucidal and reduces rabies risk by ~90%. [14]
   • Rabies Immunoglobulin (RIG): 20 IU/kg (human) or 40 IU/kg (equine). Infiltrate around wound (as much as anatomically feasible). Remainder IM at site distant from vaccine (e.g., gluteal if vaccine in deltoid). Give on Day 0 (ideally) or up to Day 7. Provides passive immunity while vaccine takes effect (2 weeks). [6,14]
   • Rabies Vaccine: Intramuscular (deltoid) on Days 0, 3, 7, 14, 28 (5-dose regimen). Provides active immunity. [6,14]
   • Tetanus: Booster if indicated.
   • Antibiotics: Not indicated (wound not infected, low-risk).
   • Contact Public Health (UKHSA in UK, CDC in USA, or local equivalent): Arrange supply of RIG and vaccine (often need to contact specialist centers).
3. If pre-exposure vaccination:
   • No RIG needed (already has some immunity).
   • Vaccine only: Days 0 and 3 (2 doses). [6,14]
   • Much simpler and cheaper → Travelers to endemic areas should consider pre-exposure vaccination (3 doses over 3-4 weeks).

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Scenario 5: MCQ - Antibiotic Choice

Question: A 45-year-old man presents with a dog bite to the hand, 6 hours post-injury. He requires antibiotic prophylaxis. He has a documented anaphylactic reaction to penicillin (angioedema and bronchospasm). Which of the following is the MOST appropriate antibiotic regimen?

A. Co-Amoxiclav 625mg TDS
B. Clindamycin 300mg QDS
C. Doxycycline 100mg BD + Metronidazole 400mg TDS
D. Cefalexin 500mg QDS
E. Clarithromycin 500mg BD

Answer: C. Doxycycline 100mg BD + Metronidazole 400mg TDS

Rationale:

• A (Co-Amoxiclav): Contraindicated (penicillin anaphylaxis). [4]
• B (Clindamycin): Does NOT cover Pasteurella or Eikenella. Inadequate. [4]
• C (Doxycycline + Metronidazole): Correct. Doxycycline covers Pasteurella, Staphylococcus, Streptococcus, Eikenella (Gram-positives and some Gram-negatives). Metronidazole covers anaerobes (Bacteroides, Fusobacterium). Together, they provide comprehensive coverage. [4]
• D (Cefalexin): 1st generation cephalosporin. Does NOT reliably cover Pasteurella or Eikenella. Also, ~1-2% cross-reactivity with penicillins in anaphylaxis (avoid if possible). [4]
• E (Clarithromycin): Macrolide. Increasing Pasteurella resistance. Does NOT cover Eikenella well. Inadequate alone. [4]

Teaching Point: For severe penicillin allergy, use Doxycycline + Metronidazole (or Fluoroquinolone + Metronidazole). Avoid Clindamycin or Macrolides alone (do NOT cover key organisms).

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Scenario 6: Viva Question - Kanavel's Signs

Examiner: "Tell me about Kanavel's signs."

Model Answer: "Kanavel's signs are four clinical features that indicate flexor tenosynovitis (infection of the flexor tendon sheath), which is a hand surgery emergency. [9]

The four signs are:

1. Finger held in slight flexion (patient keeps finger partially bent as this reduces tension on infected sheath)
2. Fusiform swelling of the affected digit (sausage-shaped finger)
3. Tenderness along the flexor tendon sheath (especially over A1 pulley at base of finger and along the flexor sheath in palm)
4. Pain on passive extension of the finger (most sensitive sign - stretching infected sheath causes severe pain)

Context: Flexor tenosynovitis usually follows penetrating trauma (e.g., bite, puncture wound from knife/glass/thorn, or spread from adjacent infection). The flexor sheath is a closed space → infection → rapid pressure rise → tendon ischemia → tendon necrosis if not treated urgently.

Management:

• Urgent hand surgery referral (same-day)
• IV antibiotics (Co-Amoxiclav or broader if severe)
• Surgical drainage in theatre: Open sheath (Brunner incision), irrigate copiously, debride necrotic tissue, leave drains. Sometimes requires proximal incision in palm as well (if infection extends).
• Post-op: IV antibiotics for 48-72 hours, then oral. Early mobilization (OT) to prevent stiffness.

Complications if delayed: Tendon necrosis → adhesions → permanent stiffness → loss of function → may need tenolysis or even amputation."

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11. Triage: When to Refer

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12. Patient/Layperson Explanation

What should I do immediately after being bitten?

Step 1: WASH THE WOUND ✅

• Run it under tap water for at least 5 minutes (ideally 10-15 minutes if animal bite in rabies area)
• Use soap if available (helps kill bacteria and viruses)
• This is the most important first step and can reduce infection risk significantly

Step 2: STOP THE BLEEDING 🩸

• Apply firm pressure with a clean cloth or tissue
• Elevate the area (e.g., raise hand above heart level)
• Most bites stop bleeding within 5-10 minutes

Step 3: COVER THE WOUND 🩹

• Use a clean, dry dressing or plaster
• Don't use creams or ointments yet (doctor will clean it properly)

Step 4: SEEK MEDICAL ATTENTION 🏥

• See a doctor within 24 hours (sooner if severe)
• Go to A&E immediately if:
  • Bite on your hand or face
  • Cat bite (any) - these get infected very easily
  • Human bite (especially if from a punch to the mouth)
  • Bite is deep or won't stop bleeding
  • You can't move your fingers/toes properly
  • You feel unwell, feverish, or dizzy
  • You are immunocompromised (diabetes, on steroids, had spleen removed, on chemotherapy)
  • Bite was from a wild animal or stray dog (rabies risk)

When do I need antibiotics?

You will likely need antibiotics if:

• ✅ Cat bite (any)
• ✅ Human bite
• ✅ Bite on your hand
• ✅ Deep or puncture wound
• ✅ You have diabetes or other medical conditions affecting immunity
• ✅ Bite is showing signs of infection (see below)

Antibiotic: Usually Co-Amoxiclav tablets, 3 times a day for 5-7 days. Finish the whole course even if it looks better.

What are signs of infection? (When to come back urgently)

🚨 See a doctor urgently if you develop:

• Redness spreading around the wound (mark the edge with a pen so you can see if it's expanding)
• Increasing pain (getting worse, not better)
• Swelling (puffy, hot)
• Pus or discharge (yellow/green fluid)
• Red streaks going up your arm or leg (lymphangitis - spreading infection)
• Fever or feeling unwell (chills, sweats, shivering)
• Can't move fingers/toes properly
• Numbness or tingling

Cat bites can get infected very quickly (within 12-24 hours) - be extra vigilant.

Do I need a tetanus jab?

Possibly. The doctor will check:

• When was your last tetanus vaccine?
  • If within 10 years → probably no booster needed
  • If more than 10 years → you'll get a booster
  • If you're not sure or never vaccinated → you'll get vaccine + possibly immunoglobulin

Tetanus is a serious infection from bacteria in soil/saliva. Vaccination is very effective and safe.

What about rabies?

In the UK/Australia/New Zealand/Western Europe: Rabies is extremely rare (these countries are rabies-free, except bats in UK).

You need rabies treatment if:

• Bitten in Asia, Africa, Latin America, or Eastern Europe (rabies is common)
• Bitten by a bat (even in UK)
• Bitten by a wild animal (fox, raccoon, monkey)
• Bitten by a stray dog that cannot be watched for 10 days

Rabies treatment: Series of injections (vaccine + immunoglobulin). This is life-saving - rabies is almost 100% fatal once symptoms start. The treatment is very safe and effective.

Will my wound be stitched?

Depends on location:

• Face: Usually stitched (heals better, less scarring) - done carefully by doctor
• Hand: Usually left open (stitching increases infection risk) - it will heal on its own or be stitched later when clean
• Puncture wounds (cat bites): Not stitched (traps bacteria inside)

How do I care for the wound at home?

Keep it clean:

• Wash hands before touching wound
• Change dressing daily (or if wet/dirty)
• Gently clean with cooled boiled water or saline (not antiseptic unless doctor says)

Keep it dry:

• Avoid getting wound soaked (quick showers OK, pat dry)

Elevate:

• If bite on hand or foot, keep it raised (use a sling, prop on pillows)
• Reduces swelling and pain

Take antibiotics:

• Finish the whole course (even if it looks better)
• Take with food if they upset your stomach

Pain relief:

• Paracetamol and/or Ibuprofen (follow packet instructions)

When can I return to work/school?

• If wound is healing well, not infected: Usually 1-3 days (unless heavy manual work)
• If infected or on antibiotics: Wait until infection is controlled (doctor will advise)
• Children: Can return to school once wound is covered and not weeping (check school policy)

Key Messages

✅ Wash wound immediately (5-15 minutes, soap and water)
✅ See a doctor within 24 hours (sooner if hand/face/cat/human)
✅ Take antibiotics if prescribed (finish full course)
✅ Watch for infection signs (redness, swelling, pus, fever)
✅ Come back urgently if infection develops
✅ Elevate hand/foot (reduces swelling)
✅ Complete tetanus vaccination if needed
✅ Rabies treatment is essential if bite in endemic country or from bat/wild animal

Questions to Ask Your Doctor

1. Do I need antibiotics?
2. Should the wound be stitched or left open?
3. When should I come back for review?
4. What infection signs should I watch for?
5. Do I need a tetanus booster?
6. (If applicable) Do I need rabies treatment?
7. When can I return to work/sport?
8. Will there be a scar? (Especially facial bites)

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13. Clinical Algorithms

Algorithm 1: Initial Assessment & Triage

BITE INJURY
    ↓
[ABCDE if major trauma/sepsis]
    ↓
HISTORY: Type (Dog/Cat/Human)? Location? Time? Tetanus status? Immunocompromised? Rabies risk?
    ↓
EXAMINATION: Wound type? Depth? Neurovascular intact? Signs of infection? Joint/tendon involvement?
    ↓
INVESTIGATIONS: X-Ray if indicated (fight bite, deep, foreign body, bone). Wound culture if infected.
    ↓
RISK STRATIFICATION:
    │
    ├─ HIGH RISK? ────────────────────────────────────────────┐
    │  (Fight bite, Hand, Cat, Human, Immunocompromised,      │
    │   Puncture, Deep, Infected, Tendon/Nerve/Joint)         │
    │                                                          ↓
    │                                             [EMERGENCY DEPARTMENT]
    │                                             Antibiotics, Imaging,
    │                                             Specialist referral,
    │                                             Consider admission
    │
    └─ LOW RISK? ─────────────────────────────────────────────┐
       (Minor dog bite, superficial, not hand/face,           │
        less than 6h, no infection, immunocompetent)                   ↓
                                                [PRIMARY CARE / MIU]
                                                Wound irrigation,
                                                Tetanus, Safety-net

Algorithm 2: Antibiotic Decision

BITE WOUND
    ↓
PROPHYLAXIS or TREATMENT?
    │
    ├─ PROPHYLAXIS (Clean wound, no infection signs)
    │      ↓
    │  Indication for antibiotics?
    │  (Cat bite, Human bite, Hand, Puncture, Deep,
    │   Near joint/bone, Immunocompromised,
    │   Delayed > 12h, Requires closure)
    │      │
    │      ├─ YES ──→ Co-Amoxiclav 625mg TDS x 5-7 days
    │      │          (If penicillin-allergic: Doxy + Metro)
    │      │
    │      └─ NO ───→ No antibiotics
    │                 (Good wound care, Safety-net)
    │
    └─ TREATMENT (Infection present)
           ↓
       Severity?
           │
           ├─ MILD (Cellulitis, afebrile, no systemic symptoms)
           │      ↓
           │  Co-Amoxiclav 625mg TDS x 7-10 days (oral)
           │  Review 24-48h
           │
           ├─ MODERATE (Abscess, lymphangitis, fever, or
           │            immunocompromised)
           │      ↓
           │  ADMIT
           │  Co-Amoxiclav 1.2g TDS IV
           │  Incision & Drainage if abscess
           │
           └─ SEVERE (Sepsis, necrotizing infection,
                      septic arthritis)
                  ↓
              EMERGENCY
              Piperacillin-Tazobactam 4.5g TDS IV
              (± Clindamycin if necrotizing)
              Urgent surgical intervention
              ICU if septic shock

Algorithm 3: Wound Closure Decision

BITE WOUND (After irrigation & debridement)
    ↓
Location?
    │
    ├─ FACE / SCALP ────────────────────────────────────────┐
    │                                                        │
    │  Fresh (less than 12-24h)? No infection?                       │
    │      ↓ YES                                            │
    │  PRIMARY CLOSURE                                      │
    │  (Loose sutures, antibiotics, follow-up 24-48h)       │
    │                                                        │
    ├─ HAND ────────────────────────────────────────────────┤
    │                                                        │
    │  LEAVE OPEN                                           │
    │  (Pack loosely, dress, elevate, antibiotics)          │
    │  Delayed primary closure at 3-5 days if clean         │
    │                                                        │
    ├─ PUNCTURE (Cat, deep)─────────────────────────────────┤
    │                                                        │
    │  LEAVE OPEN                                           │
    │  (Cannot adequately irrigate → high infection risk)   │
    │                                                        │
    ├─ INFECTED ────────────────────────────────────────────┤
    │                                                        │
    │  LEAVE OPEN                                           │
    │  (Treat infection first)                              │
    │                                                        │
    └─ OTHER (Body, limbs)──────────────────────────────────┘
                   ↓
       Fresh (less than 12h)? Low-risk (dog, not puncture)?
                   │
                   ├─ YES ──→ Consider PRIMARY CLOSURE
                   │          (Loose sutures, antibiotics)
                   │
                   └─ NO ───→ LEAVE OPEN or
                              DELAYED PRIMARY CLOSURE

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14. Quality Markers: Audit Standards

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15. References

1. Thibault C, Rousseau J. Dog bites. CMAJ. 2018;190(4):E105. doi:10.1503/cmaj.170684

2. Ortiz JF, Lezcano AJ. Dog and Cat Bites: Rapid Evidence Review. Am Fam Physician. 2023;108(4):388-395. PMID: 37983702

3. Piorunek T, Brajer-Luftmann B, Walkowiak J. Pasteurella Multocida Infection in Humans. Pathogens. 2023;12(10):1210. doi:10.3390/pathogens12101210

4. Greene C, Fritz SA. Infectious Complications of Bite Injuries. Infect Dis Clin North Am. 2021;35(1):81-93. doi:10.1016/j.idc.2020.10.005

5. Yu W, Wang L, Yang S, et al. Choice of Primary Repair in Animal Bite Wound: A Novel Management Strategy. Int Wound J. 2025;22(1):e70761. doi:10.1111/iwj.70761

6. Fooks AR, Cliquet F, Finke S, et al. Rabies. Nat Rev Dis Primers. 2017;3:17091. doi:10.1038/nrdp.2017.91

7. Henderson C, Carpenter LR, Dunn JR. Rabies risk and use of post-exposure prophylaxis associated with dog bites in Tennessee. Zoonoses Public Health. 2018;65(4):459-466. doi:10.1111/zph.12451

8. Shewring DJ, Trickett RW, Subramanian KN, et al. The management of clenched fist 'fight bite' injuries of the hand. J Hand Surg Eur Vol. 2015;40(8):819-825. doi:10.1177/1753193415576249

9. Kay M, Kang S, Fisch E, et al. The management of clenched fist injuries with local anaesthesia and field sterility. J Hand Surg Eur Vol. 2021;46(2):198-203. doi:10.1177/1753193420960588

10. Schuler F, Padberg J, Hullermann M, et al. Lethal Waterhouse-Friderichsen syndrome caused by Capnocytophaga canimorsus in an asplenic patient. BMC Infect Dis. 2022;22(1):688. doi:10.1186/s12879-022-07590-1

11. Woźniak A, Szymczak A, Piotrowska A. A case of fulminant sepsis caused by Capnocytophaga canimorsus. IDCases. 2020;21:e00798. doi:10.1016/j.idcr.2020.e00798

12. Tricard T, Bund J, Alhefzi M, et al. Eikenella corrodens bone and hip joint infection. A case report and literature review. Arch Pediatr. 2016;23(11):1191-1195. doi:10.1016/j.arcped.2016.08.011

13. UK Health Security Agency. Tetanus. In: Immunisation Against Infectious Disease (The Green Book). Updated 2023. Available at: https://www.gov.uk/government/collections/immunisation-against-infectious-disease-the-green-book

14. World Health Organization. Rabies vaccines: WHO position paper, April 2018. Wkly Epidemiol Rec. 2018;93(16):201-220. PMID: 29671810

15. Dang X, Zhao Y, Pan Y, et al. Immediate versus delayed closure of facial dog-bite wounds: Retrospective analysis and nursing care experience. Medicine (Baltimore). 2025;104(3):e45133. doi:10.1097/MD.0000000000045133

16. Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites. Cochrane Database Syst Rev. 2001;(2):CD001738. doi:10.1002/14651858.CD001738

17. Cummings P. Antibiotics to prevent infection in patients with dog bite wounds: a meta-analysis of randomized trials. Ann Emerg Med. 1994;23(3):535-540. doi:10.1016/s0196-0644(94)70073-7

18. Bystritsky R, Chambers HF. Cellulitis and Soft Tissue Infections. Ann Intern Med. 2018;168(3):ITC17-ITC32. doi:10.7326/AITC201802060

19. Rothe K, Tsokos M, Handrick W. Animal and Human Bite Wounds. Dtsch Arztebl Int. 2015;112(25-26):433-443. doi:10.3238/arztebl.2015.0433

20. Bula-Rudas FJ, Olcott JL. Human and Animal Bites. Pediatr Rev. 2018;39(10):490-500. doi:10.1542/pir.2017-0212

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Last Reviewed: 2026-01-08 | MedVellum Editorial Team

Evidence Level: High (Systematic reviews, Guidelines, High-quality observational studies)

Next Review: 2027-01-08

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Always seek immediate medical attention for bite injuries, especially if involving the hand, face, or if signs of infection develop. If you are in the UK and have been bitten, contact NHS 111 or attend your local Emergency Department.