Lesson
Triage the Person Before the Bite
Bite care begins with hemorrhage, shock, airway, anatomy, function, time, animal context, exposure biology, and host reserve rather than a product recommendation.
- Hemorrhage
- Deep anatomy
- Species
- Exposure route
- Host risk
Life threats come first
Surface size can mislead
Protect deep structures
Start clocks early
Stabilize life threats
Activate emergency services for uncontrolled bleeding, shock, airway or neck injury, amputation, major tissue loss, or penetrating chest, abdominal, pelvic, or neurovascular trauma.
Map the wound
Record species, mechanism, time, site, depth, contamination, tissue loss, bleeding, pain, and whether teeth or foreign material may remain.
Test anatomy and function
Check active motion, strength, sensation, perfusion, joint pain, tendon excursion, and distal neurovascular status. Small openings can conceal major damage.
Start prevention clocks
Document tetanus series, rabies-relevant exposure, animal availability, visible blood, hepatitis B immunity, immune status, and time since exposure.
Quick check
Checking for saved practice…
Lesson
Read the Injury Pattern Left by Teeth
Dog bites more often crush and tear, while cat bites commonly create deep narrow punctures. Anatomy and host biology determine how much danger hides below the surface.
- Crush
- Puncture
- Devitalized tissue
- Hand anatomy
- Capnocytophaga
Inspect devitalized tissue
Assume hidden inoculation
Test function carefully
Lower the referral threshold
Inspect dog-bite trauma
Look for crush injury, ragged laceration, devitalized tissue, fracture, vascular damage, and hidden injury beyond the skin edges.
Respect cat punctures
Cat teeth can inoculate tendon sheaths, joints, bone, and closed spaces. Small wounds on the hand can progress rapidly despite a mild initial appearance.
Protect function-critical sites
Bites to hands, face, feet, genitals, cartilage, joints, tendons, nerves, or vessels receive a lower threshold for direct evaluation.
Identify high-risk hosts
Asplenia, immune compromise, diabetes, decompensated liver disease, alcohol use disorder, vascular disease, edema, and limited follow-up increase the danger of serious infection.
Quick check
Checking for saved practice…
Lesson
Protect the Hand and Assess Both People
Human bites include direct bites and closed-fist injuries. Oral flora, joint penetration, tendon injury, tooth fragments, and blood exposure create risks for both people involved.
- Closed fist
- Eikenella
- Joint penetration
- Blood exposure
- Safeguarding
Include position during impact
Small wounds can be deep
Assess both people
Delay threatens function
Expose the true tract
A dorsal knuckle wound after striking teeth needs assessment across hand positions, including the position during impact. Opening the fist can move skin away from the deeper tract; inspect motion, tendon function and possible joint involvement before local anesthesia when feasible.
Assume deep anatomy is possible
Assess tendon excursion, joint pain, tooth fragments, fracture, infection, and delayed presentation. Suspected joint or tendon involvement requires urgent surgical evaluation.
Assess both exposure directions
Visible blood can expose the bitten person through the wound and the person biting through oral mucosa. Record whose blood contacted which tissue.
Preserve safety and dignity
Consider assault, intimate-partner violence, child or elder abuse, self-defense, occupational exposure, and barriers to follow-up without replacing clinical care with judgment.
Quick check
Checking for saved practice…
Lesson
Reduce Inoculum and Preserve Function
Immediate soap-and-water cleansing and copious irrigation are active treatment. Exploration, imaging, debridement, drainage, and closure decisions follow anatomy and contamination.
- Soap and water
- Irrigation
- Foreign body
- Debridement
- Closure
Reduce inoculum early
Do not probe blindly
Debride by indication
Follow-up remains essential
Clean immediately
Wash with soap and water and irrigate thoroughly. Do not postpone cleansing while waiting for rabies, tetanus, or antibiotic decisions.
Explore safely
Look for retained teeth, devitalized tissue, joint penetration, tendon injury, fracture, and foreign material. Do not probe blindly or remove deeply embedded objects casually.
Debride and drain by indication
Remove devitalized tissue selectively and drain abscesses when required. Procedure, imaging, or specialist care can be more important than changing oral antibiotics.
Choose closure deliberately
IDSA generally advises against primary closure of animal bites except selected facial wounds after thorough irrigation, cautious debridement and prophylactic antibiotics. Other wounds may be approximated. Hand punctures and contaminated wounds need particular caution; closure remains a clinical decision.
Quick check
Checking for saved practice…
Lesson
Match Therapy to Oral Flora and Host Risk
Bite infections are frequently polymicrobial. Animal oral flora, human oral flora, skin organisms, anaerobes, wound depth, devitalized tissue, and host reserve determine the microbial problem.
- Pasteurella
- Eikenella
- Anaerobes
- Capnocytophaga
- Polymicrobial
Rapid local infection can occur
Common narrow drugs can fail
Asplenia raises urgency
Source control matters
Recognize animal oral flora
Pasteurella can cause rapid local infection after dog or cat bites. Streptococci, staphylococci, Capnocytophaga, and anaerobes can also contribute.
Recognize human oral flora
Human bites can include streptococci, Staphylococcus aureus, Eikenella corrodens, and multiple anaerobic organisms.
Protect high-risk hosts
Capnocytophaga can cause fulminant sepsis after dog or cat saliva exposure, especially with asplenia, immune compromise or heavy alcohol use. Fever, confusion, gastrointestinal symptoms or rapid decline after an exposure require urgent evaluation even if the local wound seems unimpressive.
Separate targeted treatment from empirical bite coverage
CDC recommends initial intravenous beta-lactam/beta-lactamase inhibitor or carbapenem therapy for severe Capnocytophaga infection pending susceptibility results. A drug suitable for a confirmed organism does not necessarily cover the mixed flora of an undifferentiated bite.
Think by compartment
Purulence, abscess, tendon sheath, joint, bone, necrosis, and systemic illness change culture, source-control, route, and duration decisions.
Quick check
Checking for saved practice…
Lesson
Use Preemptive Antibiotics Where Risk Justifies Them
Antibiotics are not a substitute for wound care and are not required for every superficial exposure. Benefit is more plausible in human bites and high-risk animal wounds, anatomy, hosts, or closure plans.
- High-risk wound
- Human bite
- Amoxicillin clavulanate
- Allergy
- Short course
Benefit is more plausible
Complications can accelerate
Match oral flora
Prophylaxis is not closure
Identify high-risk exposure
Hand, face, foot, genital, cartilage, puncture, crush, edema, delayed presentation, deep injury, primary closure, and significant tissue destruction increase concern.
Apply species-specific criteria
Under NICE, offer prophylaxis for human or cat bites that break skin and draw blood. A nonbleeding cat puncture may still qualify if deep. For a nonbleeding human bite that breaks skin, high-risk anatomy or host factors matter. Intact-skin exposure does not require antibiotic prophylaxis.
Identify high-risk host
Immune compromise, asplenia, diabetes, decompensated liver disease, poor circulation, edema, and limited follow-up lower the threshold for preemptive therapy.
Preserve the needed spectrum
Amoxicillin clavulanate is a common oral first choice. Allergy alternatives must still cover relevant Pasteurella, Eikenella, streptococci, staphylococci, and anaerobes.
Close the stewardship loop
IDSA recommends three to five days of prophylaxis for qualifying high-risk dog or cat bites. NICE uses three days. Prophylaxis is distinct from treating an infection that is already present.
Quick check
Checking for saved practice…
Lesson
Calculate the Antibiotic Dose Before Dispensing
The drug name alone is not a complete prescription. Specify the active component, dose, interval, route, formulation, duration and reassessment plan.
- Component dose
- Weight
- Maximum dose
- Renal function
- Formulation
Use current measured weight
Amoxicillin component
Two prescribed doses
Then calculate the liquid volume
Adult oral starting point
For an adult eligible for oral therapy with adequate renal function, UCSF uses amoxicillin-clavulanate 875/125 mg twice daily. Do not use it after associated cholestatic jaundice/hepatic dysfunction or a serious beta-lactam hypersensitivity reaction. Check interactions and organ function before prescribing. Its adult pathway specifies five days for prophylaxis and ten days for treatment; these are source-specific durations, not a substitute for reassessment.
Pediatric component dosing
For children at least three months old, the UCSF oral amoxicillin-clavulanate regimen is 22.5 mg/kg per dose twice daily, calculated on amoxicillin, capped at 875 mg amoxicillin per dose. When IV treatment is needed, ampicillin-sulbactam is 50 mg ampicillin/kg per dose every six hours, capped at 2,000 mg ampicillin per dose.
Work the calculation
For a 20 kg child whose prescribed regimen is 22.5 mg amoxicillin/kg per dose, multiply 20 by 22.5 to obtain 450 mg amoxicillin per dose. Twice daily gives 900 mg amoxicillin per day. Do not interpret the per-dose instruction as a daily total. Conversion to mL requires the actual suspension strength and confirmation of its amoxicillin-to-clavulanate ratio.
Preserve coverage with allergy alternatives
The UCSF pediatric higher-risk beta-lactam allergy pathway combines TMP-SMX, 5 mg trimethoprim/kg per dose twice daily (maximum 160 mg trimethoprim), WITH clindamycin, 10 mg/kg per dose three times daily (maximum 600 mg). Its IV allergy pathway requires specialist advice. TMP-SMX is contraindicated below two months. Younger infants need a specialist plan, not extrapolation from this table. Check reaction history, renal function, potassium risk and interactions, including the contraindicated combination with dofetilide.
Reconcile the treatment plan
UCSF pediatric guidance uses three to five days for prophylaxis and seven to ten days for established infection. NICE uses a shorter initial treatment course. Name the protocol, distinguish prevention from infection, and reassess response; deep infection needs its own plan.
Adjust before dispensing
For most adult indications, UCSF reduces amoxicillin-clavulanate to 500/125 mg twice daily at creatinine clearance 10-29 mL/min and once daily below 10 mL/min. Dialysis needs a separate schedule. Never carry the standard adult dose into renal impairment without review.
Quick check
Checking for saved practice…
Lesson
Treat Infection and Secure Source Control
Established infection requires severity classification, useful microbiology, aerobic and anaerobic coverage, organ and allergy review, and prompt management of abscess or deep-space disease.
- Cellulitis
- Abscess
- Culture
- Mixed coverage
- Source control
Trajectory defines concern
Use results to narrow
Account for allergy and organs
Procedure can be decisive
Recognize progression
Increasing pain, warmth, swelling, pus, odor, spreading color change, lymphangitis, fever, systemic illness, or functional decline supports infection.
Culture selectively
NICE recommends microbiological sampling when a bite wound has discharge, whether purulent or not. Deep infection may need aspirate or tissue obtained during source control. Review results and narrow treatment when appropriate.
Cover mixed flora
Use therapy active against relevant aerobes and anaerobes. Verify allergy, renal and hepatic function, pregnancy, age, weight, interactions, severity, and oral versus intravenous feasibility.
Define treatment duration
NICE uses five days for most infected bites, with review-based extension to seven days for more extensive injury. Established bone, joint or tendon-sheath infection needs a specialist plan rather than a universal short course. Review intravenous treatment within 48 hours for possible oral switch.
Escalate deep disease
Abscess, tenosynovitis, septic arthritis, osteomyelitis, necrotizing infection, severe cellulitis, and sepsis require urgent imaging, procedure, specialist care, or parenteral therapy.
Quick check
Checking for saved practice…
Lesson
Use Public Health to Determine Rabies Risk
Rabies risk depends on a credible exposure route, mammal species, geography, animal behavior and health, severity, travel, and whether the animal can be observed or tested.
- Bat
- Reservoir species
- Geography
- Ten-day observation
- Public health
Objects do not transmit rabies
Risk varies by place
Coordinate ten-day observation
Do not guess alone
Define a credible exposure
Bites, scratches, and infectious saliva contacting broken skin or mucosa can transmit rabies. Clothing, bedding, and intact objects do not.
Use species and geography
Bats are a risk across most of the United States. Raccoon, skunk, fox, mongoose, and dog risk varies by location and travel history.
Use animal availability correctly
A healthy dog, cat, or ferret can undergo a formal ten-day observation under public-health coordination. Illness during observation triggers immediate reporting and testing decisions. Animal vaccination history does not eliminate the observation requirement; veterinary vaccination is deferred during observation to avoid confusing vaccine reactions with illness.
Use testing and uncommon-species advice
A negative animal rabies test can allow PEP to be stopped under public-health direction. Small rodents rarely require PEP, but neurologic illness in the animal warrants consultation. Do not apply dog, cat and ferret observation rules automatically to other species; obtain species-specific advice.
Escalate bat and severe exposure
Direct bat contact unless a bite or scratch can be definitively ruled out, reservoir species, multiple wounds, head or neck exposure, young children, and foreign-country dog exposure need prompt assessment.
Quick check
Checking for saved practice…
Lesson
Build Immediate and Active Rabies Protection
When PEP is indicated, immediate wound cleansing reduces inoculum, HRIG supplies passive antibody for unvaccinated people, and vaccine generates active immunity on a defined schedule.
- Wound cleansing
- HRIG
- Day zero
- Four-dose series
- Immune compromise
Begin immediately
Check vaccine and immune history
Unvaccinated, immunocompetent
Public health selects the regimen
Start with wound cleansing
Wash all wounds thoroughly with soap and water. A virucidal agent such as povidone iodine can be used for irrigation when available.
Place HRIG correctly
For an unvaccinated person, HRIG is given once at 20 IU/kg at any age. Infiltrate wounds as anatomy permits, avoiding excessive pressure in fingers or toes; give the remainder intramuscularly away from vaccine. An exposure without an identifiable wound still requires indicated HRIG, given intramuscularly away from vaccine. If initially omitted, HRIG can be given through day seven after the first vaccine dose. Do not exceed the recommended dose.
Give vaccine correctly
Unvaccinated immunocompetent people receive 1 mL of HDCV or PCECV intramuscularly on days zero, three, seven, and fourteen. Day zero means the first vaccine date. Use the deltoid or, in children, the anterolateral thigh; never use the gluteal area.
Distinguish product preparation from the clinical schedule
Reconstitute Imovax or RabAvert with its supplied sterile-water diluent and administer the full 1 mL intramuscularly immediately after preparation. Do not substitute the D5W used for HyperRab dilution. Both vaccine inserts still describe five-dose PEP for unvaccinated people; this lesson follows current CDC four-dose guidance for unvaccinated immunocompetent patients and the separate immune-compromise pathway.
Calculate before preparing HRIG
For a 60 kg patient, 20 IU/kg gives 1,200 IU: 8 mL at 150 IU/mL or 4 mL at 300 IU/mL, before any dilution. Verify the exact product. CDC lists saline for 150 IU/mL products. HyperRab 300 IU/mL labeling specifies dilution with an equal volume of D5W if more infiltration volume is needed; never use saline for this product. Dilution increases volume for wound infiltration without increasing the IU dose.
Prepare and monitor safely
Use separate syringes, needles and sites for HRIG and vaccine. HyperRab is not for intravenous administration. Screen for prior severe immunoglobulin reactions and IgA deficiency; have treatment for anaphylaxis available. Mild vaccine reactions generally do not justify interrupting PEP, while serious reactions require urgent care and public-health advice.
Adapt for immune history
Immunocompetent people with qualifying prior vaccination receive days zero and three without HRIG. For immune compromise, consult public health: the Yellow Book permits that regimen only with a documented adequate prior response and no relevant immune change. Otherwise it recommends vaccine on days zero, three, seven, fourteen and twenty-eight plus HRIG, including some previously vaccinated people. Check antibody response after either immunocompromised regimen. Pregnancy does not preclude indicated PEP.
Quick check
Checking for saved practice…
Lesson
Close Tetanus, Blood Exposure, and Follow-up Gaps
Bite care is incomplete until tetanus protection, human-bite blood exposure, infection trajectory, animal status, function, adverse effects, reporting, and safeguarding have explicit owners and dates.
- Tetanus
- HIV nPEP
- Hepatitis B
- Return rule
- Safeguarding
Document the series
Human bites expose both people
Context matters
Set a dated checkpoint
Apply tetanus wound rules
Saliva-contaminated bites are dirty or major wounds. With a complete primary series, give a booster when the last dose was five or more years ago. Unknown, absent or incomplete vaccination history requires vaccine and TIG; HIV or severe immunodeficiency also indicates TIG for these wounds. When indicated, TIG is 250 IU intramuscularly. Antibiotics do not replace tetanus prevention.
Evaluate visible-blood exposure
Human bites without blood exposure do not routinely indicate HIV nPEP. Visibly bloody saliva contacting susceptible tissue can require urgent case-by-case HIV, hepatitis B, and hepatitis C evaluation. If HIV nPEP is indicated, start as soon as possible and no later than 72 hours after exposure; do not delay indicated treatment while investigating the source.
Prevent hepatitis B after a qualifying blood exposure
For nonoccupational exposure, CDC bases prevention on source HBsAg status and the exposed person's vaccine record. With an HBsAg-positive source, an unvaccinated person needs vaccine plus HBIG; an incomplete series needs completion plus HBIG. A documented complete series without response testing calls for a booster; documented serologic response requires no booster. Known nonresponders or unusual immune histories need expert assessment.
Handle unknown source status promptly
When source HBsAg status is unknown, start or complete the vaccine series if needed; do not automatically add HBIG. Begin indicated HBV prophylaxis promptly, preferably within 24 hours. Evidence for benefit after percutaneous exposure is unlikely to extend beyond seven days; this is not a reason to wait.
Plan hepatitis C testing
There is no routine HCV antiviral postexposure prophylaxis. Obtain baseline HCV antibody with reflex RNA if positive. The 2025 CDC nPEP guidance recommends HCV RNA at three to six weeks when follow-up is indicated by an RNA-positive source, positive source antibody without RNA results, or unknown source infection status. If that RNA is negative, complete antibody testing at four to six months, with reflex RNA if positive. Prior antibody positivity requires an RNA-based plan. New hepatitis symptoms warrant earlier RNA testing and clinical evaluation.
Reassess early
High-risk and infected bites need a clear twenty-four to forty-eight-hour checkpoint. Worsening at any time, systemic illness, disproportionate pain, lymphangitis, or functional decline requires escalation.
Track the whole event
Document antibiotics, adverse effects, wound progress, motion, sensation, animal observation or testing, rabies plan, reporting, safeguarding, and access barriers.
Quick check
Checking for saved practice…
Module practice
Check the connections.
Each attempt draws 10 questions from the complete 43 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.
- FDA Imovax Rabies Prescribing Information
- FDA RabAvert Prescribing Information
- DailyMed Kedrab Prescribing Information
- DailyMed Bactrim Contraindications and Precautions
- DailyMed Augmentin Dosing and Contraindications
- CDC Nonoccupational Hepatitis B Exposure Prevention
- CDC Hepatitis C Exposure Testing
- CDC Rabies Risk Assessment Algorithm, September 2026
- FDA HyperRab Prescribing Information
- UCSF Pediatric Bite Dosing
- UCSF Adult Bite Pathway
- UCSF Amoxicillin-Clavulanate Renal Dosing
- CDC Yellow Book: Rabies in Immunocompromised Travelers
- RCH Bite Injury Examination
- CDC Rabies Biologics
- CDC Rabies PEP Guidance
- CDC Rabies Clinical Screening
- CDC Rabies Veterinary Observation
- CDC Capnocytophaga Clinical Overview
- CDC 2025 Nonoccupational HIV PEP
- CDC Tetanus Wound Management
- IDSA Skin and Soft Tissue Infection Guideline
- NICE Human and Animal Bites