Animal Bites

Domestic animal bites (cats & dogs) — Felis catus (cat) Canis lupus familiaris (dog)

Initial care (non-medical)

• Irrigate copiously with normal saline; avoid harsh antiseptics inside the wound.
• Debride devitalized tissue; assess depth, tendon, joint, neurovascular status.
• Elevation; remove rings/watches; hemostasis by gentle pressure.
• Primary closure usually avoided for puncture wounds/hand bites; consider delayed closure. Facial or genital wounds may be closed after thorough irrigation.
• Tetanus: give booster if >5 years for dirty wounds (Td/Tdap).
• Rabies observation: healthy dog/cat that can be observed for 10 days → defer PEP unless animal becomes ill; unknown/ill animal → consult public health.

When to use antibiotics

• All cat bites (high risk for Pasteurella multocida).
• Dog bites to hand/face/genitals; deep puncture, crush injury, edema, immunocompromised, diabetes, asplenia, delayed presentation >12h (extremity) or >24h (face).

Avoid clindamycin monotherapy for cat/dog bites (poor Pasteurella coverage).

Scenario	First-line (adult)	Alternatives / allergies	Duration
Prophylaxis (no infection)	Amoxicillin-clavulanate 875/125 mg PO q12h	Penicillin allergy: • Doxycycline 100 mg PO q12h (avoid in pregnancy) • or TMP-SMX DS PO q12h + metronidazole 500 mg q8h (or clindamycin 300 mg q6–8h)	3–5 days
Established cellulitis	Amoxicillin-clavulanate 875/125 mg PO q12h	As above; if severe β-lactam allergy: moxifloxacin 400 mg PO daily (adult)	5–7 days (extend if slow response)
Severe infection / systemic signs	Ampicillin-sulbactam 3 g IV q6h	Pip-tazo 4.5 g IV q6–8h; or ceftriaxone 2 g IV daily + metronidazole 500 mg q8h. Add MRSA coverage if indicated (e.g., vancomycin per protocol).	7–14+ days based on source/depth
Special situations	Hand bites: low threshold for surgery if abscess, tenosynovitis, septic arthritis, osteomyelitis, or deep space infection. Obtain imaging for foreign body or bone involvement as indicated.

Common microbes: Pasteurella multocida (cats), Capnocytophaga canimorsus (dogs), streptococci, staphylococci (incl. MRSA risk), anaerobes.

Tick bites (USA) — Ixodes scapularis Amblyomma americanum Dermacentor variabilis

Immediate care

• Remove with fine tweezers close to skin; steady upward pull. Clean with soap/water.
• Save/photograph tick if possible (species/attachment time).
• No heat, nail polish, petroleum jelly.

Post-exposure prophylaxis (Lyme)

If all are true: (1) Ixodes species likely, (2) local Lyme risk moderate–high, (3) attached ≥36 h, (4) prophylaxis within 72 h of removal, (5) doxycycline safe → give single-dose doxycycline.

Indication	Adult	Pediatric	Notes
Lyme prophylaxis	Doxycycline 200 mg PO once	Doxycycline 4.4 mg/kg PO once (max 200 mg)	Not for pregnancy/breastfeeding; instead observe and treat if symptoms develop.
Early Lyme disease (erythema migrans)	Doxycycline 100 mg PO q12h × 10 days	Doxycycline 4.4 mg/kg/day divided q12h × 10 days (max 100 mg q12h)	Alternatives: amoxicillin or cefuroxime if doxy contraindicated.
Other tick-borne diseases	Consider ehrlichiosis, anaplasmosis, RMSF; doxycycline is first-line for suspected rickettsial illness in adults and children.

Wild animal bites (USA woods/fields) — Procyon lotor (raccoon) Vulpes vulpes (fox) Mephitis mephitis (skunk) Chiroptera (bats)

Rabies risk & action

• High risk: bats, raccoons, skunks, foxes, unknown wild carnivores — initiate PEP unless animal tests negative.
• Rodents & lagomorphs (squirrels, mice, rats, rabbits): rabies PEP generally not indicated.
• Rabies PEP (unvaccinated): HRIG 20 IU/kg: infiltrate around wound; remainder IM distant site + vaccine IM days 0, 3, 7, 14.
• Previously vaccinated: vaccine IM days 0 & 3; no HRIG.

Antibiotics

• Use dog/cat bite regimens (mixed flora incl. aerobes/anaerobes). See table below.

Scenario	Antibiotic choice	Duration
Prophylaxis (high-risk wounds)	Amoxicillin-clavulanate 875/125 mg PO q12h (adult) β-lactam allergy: doxycycline; or TMP-SMX + metronidazole/clindamycin.	3–5 days
Cellulitis	As above; consider MRSA risk and add coverage if needed.	5–7 days
Severe/systemic	Ampicillin-sulbactam IV; or pip-tazo IV; tailor per cultures.	7–14+ days

Always perform thorough irrigation, assess tetanus, and coordinate with public health for testing and PEP decisions.

Snakebites (with North Carolina focus) — Agkistrodon contortrix (copperhead) Agkistrodon piscivorus (cottonmouth) Crotalus horridus (timber rattlesnake) Sistrurus miliarius (pygmy rattlesnake)

Immediate actions (field/ED)

• Stay calm, immobilize limb at heart level; remove rings/watches; mark advancing edema every 15–20 min.
• Do NOT use tourniquet, ice, incision/suction, electric shock, or attempt to catch snake.
• Rapid transport; establish IV access; pain control; basic labs, coags, fibrinogen, platelets, CK; photograph fang marks and swelling lines.

When to give antivenom

• Progressive swelling beyond bite area, systemic symptoms (hypotension, vomiting, neuro signs), coagulopathy or thrombocytopenia, significant local tissue injury.
• Most NC venomous envenomations are copperhead; antivenom often indicated if swelling progresses.

Antivenom	Initial control	Maintenance / notes
CroFab® (Crotalidae polyvalent immune Fab)	4–6 vials IV; repeat q60 min until initial control (halt of swelling, improving labs) achieved	Then 2 vials IV q6h × 3 doses. Monitor for recurrent coagulopathy.
Anavip® (F(ab')₂)	10 vials IV; may repeat 10 vials if no initial control in 60 min	Longer half-life; fewer recurrence issues; no scheduled maintenance, dose per response.
Supportive care	Tetanus up to date; avoid prophylactic antibiotics (unless wound is grossly contaminated or delayed presentation). Consult poison control/toxicology. Surgical fasciotomy is rarely needed—only for true compartment syndrome after antivenom and pressure measurements.

Coral snakes are not typical in NC; elapid neurotoxicity requires different antivenom and management—consult toxicology if suspected.

Rabies & tetanus quick reference

Topic	Key points
Rabies PEP (unvaccinated)	HRIG 20 IU/kg (infiltrate around wound; remainder IM, different site from vaccine) + vaccine IM days 0, 3, 7, 14.
Rabies PEP (previously vaccinated)	Vaccine IM days 0 & 3; no HRIG.
Tetanus	Dirty wounds: booster if >5 years; clean/minor: booster if >10 years. TIG if unknown/never immunized and wound is dirty.

Scientific terms you can use in notes: Felis catus bite (domestic cat) Canis lupus familiaris bite (domestic dog) Procyon lotor bite (raccoon) Vulpes vulpes bite (red fox) Mephitis mephitis bite (striped skunk)

Clinical content is a quick-reference and not a substitute for local guidelines or toxicology/public-health consultation. Adjust dosing for renal/hepatic function, pregnancy, pediatrics.