Contents

Search

mammal bite

Epidemiology: 1) dog bites account for 70-90% of animal bites 2) more than 1/2 of victims are children 3) cat bites account for 5-20% of bites a) higher incidence of infection than dog bites b) more common in women 4) human & rodent bites comprise majority of other animal bites Pathology: - bite wounds usually result in polymicrobial infections - aerobic & anaerobic bacteria originate from animal's oral flora, victim's skin & surrounding environment [10] - cat bites are more likely to become infected than dog bites [2] History: 1) regarding the animal - type of animal - relationship of animal to victim - circumstance of bite (provoked vs unprovoked) - time & location of incidence - vaccination & health status of animal - current location of the animal 2) regarding the victim - tetanus immunization status - first aid measures - history of immunocompromise, splenectomy - symptoms of musculoskeletal, neurologic, lymphatic or vascular compromise Clinical manifestations: 1) extremities involved in 75% of cases 2) head & neck injuries are next most common 3) key signs a) hematoma b) motor weakness c) decreased capillary refill d) decreased sensation e) diminished range of motion f) edema g) evidence of crush injury or devitalized tissue h) cellulitis or purulent wound drainage i) loss of function 4) complications may arise from a) skull penetration following a bite to the cranium in a small child b) bites over a joint c) puncture wounds d) lip & face bites in children 5) high risk bites indicating antibiotic therapy a) all human bites (highest risk of infection) b) all cat bites c) hand & foot wounds d) wound surgically debrided e) puncture wounds f) wounds involving joints, ligaments, tendons or bones g) bites in immunocompromised individuals 1] primary immunologic disorder 2] HIV 3] chronic alcoholism 4] asplenism 5] diabetes mellitus 6] prosthetic valves or joints 7] immunosuppressive therapy 6) low risk wounds include lacerations of the face, extremities & body Laboratory: 1) generally laboratory testing is not indicated 2) wound & blood cultures in immunocompromised host, evidence of abscess, severe cellulitis, devitalized tissue, sepsis, or failure of empiric antibiotics 3) gram stain on fresh uninfected wounds correlated poorly with subsequent infections Radiology: - plain radiographs a) bony penetration suspected b) deep bites c) puncture wounds d) human bites - MRI or CT may also be indicated Complications: 1) neurovascular damage 2) infection a) bony or joint penetration with infection 1] osteomyelitis 2] septic bursitis b) cellulitis c) septic shock d) meningitis & cerebral abscess e) prosthetic valve & joint infection f) organisms secondary to human bites 1] Staphylococcal species 2] Streptococcal species 3] Eikenella corrodens 4] Haemophilus species 5] oral anaerobes a] Prevotella species b] Porphyromonas species g) organisms secondary to other animal bites 1] Staphylococcal species, including MRSA 2] Streptococcal species 3] Pasteurella canis & Pasteurella multocida 4] Capnocytophaga canimorsus 5] other aerobic & anaerobic bacteria - Bacteroides, Porphyromonas, Fusobacterium 3) compartment syndrome 4) musculotendinous injury 5) severe crush injury 6) fistulous tracts 7) scarring & disfiguration Management: 1) wound care a) inspect for neurovascular & muscle integrity b) debride & irrigate - normal saline - 1% povidone-iodine - 20% soap & water or ethyl alcohol for at least 10 minutes followed by 1% benalkonium chloride if rabies is suspected, rinse with normal saline c) generally delayed closure of wound is prudent - especially if bite involves the head, hands, or feet, crush injury or signs of edema - facial wounds may be exception [2] d) elevation of extremity 2) empiric antibiotic therapy a) prophylactic antibiotics for [2] - wounds on the hand or near a joint - wounds on face or genitalia [2] - moderate or severe wounds, deep puncture wounds [2] - crush injury - wounds associated with edema - immunocompromised patients [2] b) 3-5 days prophylactic antibiotics if no overt signs of infection [2] c) of no benefit [6]; may reduce risk of wound infection [7] d) all infected bites [2] e) all human bites [2] - ampicillin sulbactam (Unasyn) [2] - amoxicillin-clavulanate (Augmentin) [2] - cefoxitin or cefotetan - nafcillin IV followed by oral dicloxacillin [1] - if allergic to penicillin - clindamycin & moxifloxacin [2] or levofloxacin & metronidazole [2] - tetracycline [1] - also see clenched fist injury f) cat bites - amoxicillin clavulanate (Augmentin) TID or ampicillin sulbactam (Unasyn) [2] - nafcillin followed by dicloxacillin, then penicillin g) dog bites - amoxicillin clavulanate (Augmentin) TID or ampicillin sulbactam (Unasyn) [2] - nafcillin followed by dicloxacillin or cefazolin followed by cephalexin h) if MRSA is suspected - amoxicillin clavulanate TID or ampicillin sulbactam plus vancomycin [2] i) if penicillin allergy - Bactrim, doxycycline, or minocycline (MRSA, Pasteurella) plus clindamycin (MRSA, Streptoccus, anaerobes) [10] 3) hospitalize if: - fever - sepsis - spreading cellulitis - severe edema - crush injury - loss of function - immunocompromised patient - likely to be non-compliant 4) tetanus prophylaxis a) tetanus toxoid 0.5 cc IM - high risk wound, no booster within 5 years - low risk wound, no booster within 10 years - no prior immunization or immunization status unknown b) tetanus immune globulin - high risk wound no booster within 10 years - no prior immunization or immunization status unknown 5) rabies post exposure prophylaxis guidelines a) wild animals - prophylaxis for bites from rabies-endemic species - bats anywhere is USA - skunks, foxes, raccoons based upon local public health recommendations - prophylaxis for bites from wild carnivores (coyotes & bobcats) & groundhogs in rabies-endemic area - no treatment necessary for provoked bite from animal where rabies is not endemic in species involved b) domestic animals - no treatment indicated if animal is immunized or healthy & available for 10 days of observation - treatment indicated for - dogs in most developing countries & in USA along the Mexican border - animal rabid or suspected rabid c) if uncertain, consult local health department c) specific treatment recommendations - previously vaccinated with documented antibody response - 2 doses of human diploid cell vaccine (HDCV) or rabies vaccine adsorbed (RVA) 1 mL IM (deltoid) on days 1 & 3 - do not give rabies immune globulin (RIG) - unvaccinated individuals - rabies immune globulin (RIG), 20 IU/kg - 1/2 infiltrated into the wound the - other 1/2 IM (gluteal) - 5 doses of HDCV or RVA 1.0 mL IM (deltoid) on days 1, 2, 7, 14, 28 6) evaluation of exposure to viral & other pathogens - hepatitis B, hepatitis C, HIV1 (human bites) - hepatitis B prophylaxis as indicated - hepatitis B immune globulin 0.06 mL/kg IM on days 1 & 30 7) established wound infections a) treat aggressively b) adequate surgical debridement & drainage c) hospitalize for severe blood loss, sepsis, open fracture, osteomyelitis, severe hand injury, deep tissue injury d) parenteral antibiotics for hospitalized patients - empiric coverage of gram positive, gram negative & anaerobic organisms e) frequent follow-up 8) precautions should be taken if bite is from a known carrier of HIV 9) patient education - do not run if confronted by threatening dog - children should not be left alone with an animal - pet ferrets are particularly notorious for bites - virtually all animals give warning before biting

Related

cat stratch clenched fist injury; closed fist injury; reverse bite injury; fight bite

General

animal bite

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 1169-70
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018, 2021.
  3. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 571
  4. Physician's First Watch Massachusetts Medical Society Managing Infection Passed from Pets to Humans via Bite Injuries Lancet Infectious Diseases (pending publication) June 22, 2009
  5. Stevens DL, Bisno AL, Chambers HF, Everett ED Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis. 2005 Nov 15;41(10):1373-406. Epub 2005 Oct 14 PMID: 16231249
  6. The NNT: Antibiotics for Prophylaxis of Animal Bites. http://www.thennt.com/nnt/antibiotics-for-animal-bites/ - Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites. Cochrane Database Syst Rev. 2001;(2):CD001738. PMID: 11406003
  7. Henton J, Jain A. Cochrane corner: antibiotic prophylaxis for mammalian bites (intervention review). J Hand Surg Eur Vol. 2012 Oct;37(8):804-6. Review. PMID: 23042781
  8. Oehler RL, Velez AP, Mizrachi M, Lamarche J, Gompf S. Bite-related and septic syndromes caused by cats and dogs. Lancet Infect Dis. 2009 Jul;9(7):439-47. Review. PMID: 19555903
  9. NEJM Knowledge+ Question of the Week. May 30, 2017 https://knowledgeplus.nejm.org/question-of-week/530 - Stevens DL, Bisno AL, Chambers HF et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis 2014 Jul 15; 59:147 PMID: 24947530 - Stevens DL, Bisno AL, Chambers HF et al Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014 Jul 15;59(2):e10-52. Erratum in: Clin Infect Dis. 2015 May 1;60(9):1448. Dosage error in article text. PMID: 24973422 - Swartz MN. Clinical practice. Cellulitis. N Engl J Med 2004 Feb 26; 350:904 PMID: 14985488 http://www.nejm.org/doi/full/10.1056/NEJMcp031807
  10. NEJM Knowledge+ Question of the Week. May 22, 2018 https://knowledgeplus.nejm.org/question-of-week/4732/
  11. Ellis R, Ellis C. Dog and cat bites. Am Fam Physician 2014 Aug 15; 90:239 PMID: 25250997 Free full text
  12. Esposito S, Picciolli I, Semino M, Principi N. Dog and cat bite-associated infections in children. Eur J Clin Microbiol Infect Dis 2013 Aug; 32:971 PMID: 23404346
  13. Talan DA, Citron DM, Abrahamian FM, Moran GJ, Goldstein EJ. Bacteriologic analysis of infected dog and cat bites. N Engl J Med 1999 Jan 14; 340:85 PMID: 9887159 Free full text https://www.nejm.org/doi/full/10.1056/NEJM199901143400202