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DEFINITIONS AND EPIDEMIOLOGY

Animal bites are a common occurrence, with approximately half of all Americans reporting an animal bite at some point in their life. In the United States, nearly all (80–90%) animal bites are by dogs, and therefore national surveillance is largely based on these injuries. Cat (5–10%) and human (2–3%) bites account for most of the rest.1

An estimated 4.5 million dog bites occur every year in the United States. Most dog bites are minor and do not require medical treatment. Of the approximately 300,000 people who suffer dog bites and seek care in emergency departments annually, over 97% are treated and discharged home.2,3 Children aged <15 years account for approximately 42% of those evaluated in emergency departments, with injury rates highest among those 5–9 years of age (Figure 49-1). Among young children and early adolescents, males are bitten more often than females, but this sex difference is not seen in those older than 15 years.2

FIGURE 49-1.

Dog-bite-related emergency department visits by age. [Data from Centers for Disease Control and Prevention (CDC). Nonfatal dog bite-related injuries treated in hospital emergency departments-United States, 2001. MMWR. 2003 Jul 4;52(26):605-610. ]

INJURY LOCATION

Most dog-bite injuries occur on the extremities, with 45% involving the arm or hand and 26% involving the leg or foot. However, the location of injury is strongly influenced by age (Figure 49-2). For children younger than 4 years, most (65%) bite wound injuries involve the head and neck. For older adolescents, injuries are overwhelmingly located on the extremities (86%).2 The predominance of facial wounds in infants and toddlers is related to their stature, which places the face in close proximity to the animal’s mouth, as well as possibly provoking behaviors such as hugging and kissing. In comparison, older children are better able to defend themselves and tend to suffer wounds on their arms and hands.4 Most pediatric patients suffer multiple bite wounds during a biting event.4

FIGURE 49-2.

Body part injured by nonfatal dog bites. [Data from Centers for Disease Control and Prevention (CDC). Nonfatal dog bite-related injuries treated in hospital emergency departments-United States, 2001. MMWR. 2003 Jul 4;52(26):605-610.]

Most dog-bite injuries are inflicted by a dog known to the victim; over 70% of dog-bite wounds presenting to the emergency department are inflicted by a family pet or a neighborhood pet.4,5

INFECTION RATES

Infection rates from bite wounds vary greatly depending on the type of animal, body part affected, type of injury sustained, and victim characteristics. All bite wounds should be assumed to be contaminated with bacteria. The inoculated bacteria typically consist of the oral flora of the animal. Rarely, the infecting organism comes from the victim’s own skin flora.6 Bacteriology varies by the biting ...

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