crush injuries with infection-prone devitalized tissue, a result of the enormous pressures (200 to 400 lb/square inch) dogs can generate in their bites However, only 5% to 10% of dog bites become infected, probably because the resulting lacerations and abrasions are so accessible to good wound hygiene The risk of infection is directly related to the location of the bite, with highest risk in bites of the hands and feet The feline bite is a deep puncture wound that is difficult to irrigate or cleanse, hence its high infection rate (up to 50% in some series) The penetration of tendons, vessels, facial compartments, and bones also increases the risk of infection The hand offers all these anatomic components in a relatively small cross-sectional area, hence its increased risk of infection, regardless of the biting species Aerobic and anaerobic bacteria indigenous to mammalian oral flora are inoculated into the wound during biting The most commonly isolated bacteria in infected cat and dog bite wounds are Staphylococcus aureus and Pasteurella species, a gram-negative rod In one series, Pasteurella multocida and Pasteurella canis were found in 50% and 80% of infected dog and cat wounds, respectively Other more common bacteria have also been isolated: streptococci, coagulasenegative staphylococci, S aureus, and enteric bacteria Anaerobic bacteria are usually recovered only in mixed cultures with aerobes Human bite infections are mixed bacterial infections, with Streptococcus viridans or S aureus being the predominant organism Anaerobic bacteria, especially Bacteroides and Peptostreptococcus species, are commonly cultured More serious morbidity in infected human bite wounds of the hand has been associated with S aureus and Eikenella corrodens, a facultative anaerobe Finally, the multiple systemic diseases that may be transmitted by mammalian bites need to be considered Clinical Assessment Mammalian bite wounds cause a spectrum of tissue injuries from trivial to lifethreatening Scratches, abrasions, contusions, punctures, lacerations, and their complications are commonly seen in the ED The complications usually involve secondary infections that can be severe and lead to sepsis, meningitis, endocarditis, and peritonitis, or damage to structures that underlie the bite Dog bites are insignificant lesions in at least half of the cases that come to medical attention, 5% to 10% warrant suturing, and 2% require hospital admission Other than bites on the hand, the rate of secondary infection in dog bites given good local care approximates that of nonbite wounds Young children suffer more serious canine injuries, especially in the head and neck region On rare occasions, life-threatening injuries occur, including