Animal and human bites: clean, close or leave open

What it is

Bite wounds combine a crush or tear with heavy contamination by mouth flora, so infection is the main danger. Dog bites are the most common; they tear and crush, and on the face and scalp they usually do well. Cat bites are small, deep punctures that often reach tendon sheaths and joints and become infected more often, typically with Pasteurella, within hours. Human bites carry streptococci, staphylococci, anaerobes and Eikenella; the classic dangerous one is the clenched-fist injury («fight bite»), a small cut over a knuckle from a punch to the teeth that can open the joint or the extensor tendon. Management is the same in order: control bleeding, assess neurovascular and tendon function, irrigate generously and debride, decide whether to close, consider antibiotic prophylaxis (amoxicillin with clavulanate is the usual first choice when indicated), and assess the risk of tetanus and, for mammal bites, rabies. In Colombia, bites by animals that can transmit rabies are reported to the public-health surveillance system and managed by its protocol, with wound washing and, depending on risk, rabies vaccine and immunoglobulin. Human bites also need assessment for blood-borne viruses (hepatitis B and C, HIV).

Indications

• Primary closure: clean, recent dog bites of the face and scalp after thorough irrigation and debridement.
• Leave open or close late: cat bites, punctures, hand and foot bites, crush wounds, late or infected wounds.
• Prophylactic antibiotics: high-risk wounds (cat, human, hand, deep puncture, crush, near a joint or bone, immunosuppression, asplenia).
• Rabies post-exposure prophylaxis: decided by animal species, its health and whether it can be observed, and the type of exposure.
• Blood-borne virus assessment after human bites that break the skin, for both the bitten and the biter.

Contraindications and precautions

• Do not close infected bites or those with devitalised tissue that cannot be removed.
• Never close a clenched-fist injury primarily; the joint or tendon may be contaminated.
• Bites in children may hide deep injuries, including skull penetration from large dog bites on the scalp.
• Immunosuppressed, asplenic, diabetic and cirrhotic patients are at risk of rapid, severe infection.
• Bites near the hand, a joint, a prosthesis or bone need a low threshold for radiograph and surgical review.

Equipment

• Gloves, eye protection, soap and running water for the first wash.
• Irrigation set with sterile saline or clean drinkable tap water and a syringe with splash shield.
• Local anaesthetic, forceps, scissors and a scalpel for debridement.
• Sutures or adhesive strips for wounds that can be closed, and dressings for those left open.
• Splint for hand bites, and access to vaccines and immunoglobulins according to the local protocol.

Step by step (and why)

1. Ask what animal or person bit, when, its health and vaccine status, and whether it can be watched — this sets rabies risk.
2. Wash at once with soap and plenty of water — it removes saliva and virus and lowers rabies and bacterial risk.
3. Check tendons, nerves, pulses and joints; for fist injuries examine with the fist clenched — the tendon cut hides when the hand opens.
4. Order a radiograph for bites over bone or joints or if a tooth fragment is possible — it shows fractures, teeth and air in a joint.
5. Anaesthetise, irrigate generously and debride dead tissue — removing bacteria and dead tissue is the main prevention.
6. Close only low-risk wounds, mainly facial; leave the others open or loosely approximated — closing traps bacteria.
7. Start prophylactic antibiotics for high-risk bites — cat, human and hand bites become infected often.
8. Check tetanus status and, for mammals, rabies post-exposure needs — both are preventable and time-sensitive.
9. Elevate and splint bitten hands — rest and elevation reduce swelling and spread of infection.

Complications

• Wound infection and cellulitis, often within 24 hours with Pasteurella after cat and dog bites.
• Tenosynovitis, septic arthritis and osteomyelitis after deep hand bites and fist injuries.
• Abscess and, rarely, necrotising soft-tissue infection.
• Severe sepsis with Capnocytophaga after dog bites in asplenic or alcohol-dependent patients.
• Rabies and tetanus if prophylaxis is missed; blood-borne virus transmission after human bites.

Next step

• Report bites by animals that can transmit rabies to the health authority and follow the national protocol for vaccine and immunoglobulin.
• Refer the same day to hand or plastic surgery for fist injuries, joint or tendon involvement and complex facial bites.
• Review all bites in 24–48 hours, sooner for hand bites or worsening pain, redness or swelling.
• After a human bite, offer testing and post-exposure measures for hepatitis B, hepatitis C and HIV according to protocol.
• Teach the patient to keep the limb elevated, finish the antibiotic course if prescribed and return with fever, pus or spreading redness.

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Elsewhere in DurgiPedia

• Wound care and dressings: cleaning and choosing a dressing

Connections

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Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.

Sources: Animal Bites (StatPearls (NCBI Bookshelf), 2026); Human Bites (StatPearls (NCBI Bookshelf), 2023).

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